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Accuracy of Malignant Hyperthermia Diagnoses in Hospital Discharge Records



Background: In 1997, the International Classification of Diseases (ICD), 9th Revision Clinical Modification (ICD-9) coding system introduced the code for malignant hyperthermia (MH) (995.86). The aim of this study was to estimate the accuracy of coding for MH in hospital discharge records. Methods: An expert panel of anesthesiologists reviewed medical records for patients with a discharge diagnosis of MH based on ICD-9 or ICD-10 codes from January 1, 2006 to December 31, 2008 at six tertiary care medical centers in North America. All cases were categorized as possible, probable, or fulminant MH, history of MH (family or personal) or other. Results: A total of 47 medical records with MH diagnoses were reviewed; 68.1% had a documented surgical procedure and general anesthesia, and 23.4% (95% CI, 12.3-38.0%) had a possible, probable, or fulminant MH event. Dantrolene was given in 81% of the MH events. All patients judged to have an incident MH event survived to discharge. Family and personal history of MH accounted for 46.8% of cases. High fever without evidence of MH during admission accounted for 23.4%, and the reason for MH coding was unclear in 6.4% of cases. Conclusions: Approximately one quarter of ICD-9 or ICD-10 coded MH diagnoses in hospital discharge records refer to incident MH episodes and an additional 47% to MH susceptibility (including personal history or family history). Information such as surgical procedure, anesthesia billing data, and dantrolene administration may aid in identifying incident MH cases among those with an ICD-9 or ICD-10 coded MH diagnosis in their hospital discharge records.
Anesthesiology, V 122 • No 1 55 January 2015
MALIGNANT hyperthermia (MH) is a rare pharmaco-
genetic disorder of skeletal muscle metabolism. When
a susceptible patient is exposed to a triggering agent (haloge-
nated volatile anesthetic agent and/or succinylcholine) or event
(such as elevated environmental heat along with exercise), a
potentially fatal hypermetabolic reaction can occur.1 In 1997,
the International Classification of Diseases (ICD), 9th Revision
Clinical Modification coding system (ICD-9) added a code for
“malignant hyperthermia: malignant hyperpyrexia due to anes-
thesia” (995.86). e availability of a special ICD code for MH
has made it possible to conduct epidemiological research related
to MH, including use of the code to evaluate MH prevalence,
trends in MH occurrence, and coexisting diseases.2–4
However, the validity of the findings from studies based
on ICD-coded data has been a serious concern. ICD codes
are prone to error at several different levels including but
not limited to physician, coding, and sequencing errors.5,6
Physician errors occur when a diagnosis is omitted from
the record, made incorrectly, or improperly recorded using
the wrong terminology. Coding errors can then occur when
data abstracters, usually nonmedical personnel, misinterpret
or incompletely review the chart and make incorrect deci-
sions about which diagnoses to code.6 Sequencing errors are
defined as improper assignment of a primary diagnosis ver-
sus a secondary diagnosis.5
Studies on the accuracy of ICD coded diagnoses vary
widely in their findings due to the fact that each diagno-
sis and procedure is prone to its own unique rate and type
What We Already Know about This Topic
• Theaccuracy ofInternational ClassicationofDiseases(ICD)
coding for the purpose of registry researchhas been ques-
• AnICDcode formalignant hyperthermiawas createdin the
What This Article Tells Us That Is New
• InreviewbyanexpertpanelofICDcodingformalignanthyper-
thermiaovera 3-yrperiod,approximately70%ofcodedcases
• Themostcommonreasonforinaccuratecodingwashighfe-
Copyright © 2014, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins. Anesthesiology 2015; 122:55-63
Background: In 1997, the International Classification of Diseases (ICD), 9th Revision Clinical Modification (ICD-9) coding
system introduced the code for malignant hyperthermia (MH) (995.86). e aim of this study was to estimate the accuracy
of coding for MH in hospital discharge records.
Methods: An expert panel of anesthesiologists reviewed medical records for patients with a discharge diagnosis of MH based
on ICD-9 or ICD-10 codes from January 1, 2006 to December 31, 2008 at six tertiary care medical centers in North America.
All cases were categorized as possible, probable, or fulminant MH, history of MH (family or personal) or other.
Results: A total of 47 medical records with MH diagnoses were reviewed; 68.1% had a documented surgical procedure and
general anesthesia, and 23.4% (95% CI, 12.3–38.0%) had a possible, probable, or fulminant MH event. Dantrolene was
given in 81% of the MH events. All patients judged to have an incident MH event survived to discharge. Family and personal
history of MH accounted for 46.8% of cases. High fever without evidence of MH during admission accounted for 23.4%,
and the reason for MH coding was unclear in 6.4% of cases.
Conclusions: Approximately one quarter of ICD-9 or ICD-10 coded MH diagnoses in hospital discharge records refer to
incident MH episodes and an additional 47% to MH susceptibility (including personal history or family history). Informa-
tion such as surgical procedure, anesthesia billing data, and dantrolene administration may aid in identifying incident MH
cases among those with an ICD-9 or ICD-10 coded MH diagnosis in their hospital discharge records. (Anesthesiology
2015; 122:55-63)
Preliminary results were presented at the American Society of Anesthesiologists annual meeting, Washington, D.C., October 16, 2012, and
at the International Anesthesia Research Society annual meeting, Montreal, Quebec, Canada, May 17–20, 2014.
Submitted for publication May 14, 2014. Accepted for publication August 13, 2014. From the Department of Anesthesiology, Columbia
University College of Physicians and Surgeons, New York, New York (T.P., B.H.L.); Department of Medical Education and Clinical Research,
Saint Barnabas Medical Center, Livingston, New Jersey (H.R.); Department of Anesthesiology, Northwestern University Feinberg School of
Medicine, Chicago, Illinois (C.A.W.); Department of Anesthesiology, Toronto General Hospital, Toronto, Ontario, Canada (S.R.); Departments
of Anesthesiology and Epidemiology, Columbia University College of Physicians and Surgeons and Mailman School of Public Health, New
York, New York (J.E.B., G.L.); and Departments of Anesthesiology and Pediatrics, Columbia University College of Physicians and Surgeons,
New York, New York (L.S.S.).
Accuracy of Malignant Hyperthermia Diagnoses in
Hospital Discharge Records
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Anesthesiology 2015; 122:55-63 56 Pinyavat et al.
Accuracy of ICD Code for “Malignant Hyperthermia”
of errors. Factors influencing the accuracy of ICD-coded
diagnoses include disease type, current state of medical
knowledge and technology, clinical acumen, participation
of various practitioners from patient to administrative per-
sonnel, and implementation of coding practices. Codes are
most likely to be accurate when the disease is clearly defined
with observable signs and symptoms, physician experts
record the diagnosis in the chart, experienced coders with
access to all patient data assign the code, and the code is
not new.7 One study of 7,050 Medicare discharges from a
national sampling of U.S. hospitals found that while the
overall accuracy was 78.2%, it varied widely across different
conditions. e positive predictive value in this study was
highest for hip fractures (94%) and lowest for peripheral
vascular disease (50%).8
We conducted a critical review of a sample of hospital-
izations containing the ICD code for MH at discharge to
estimate the accuracy of coding, identify common errors,
and develop strategies to improve the identification of inci-
dent MH episodes using ICD and other administrative data.
e medical records reviewed in this study were for the 3-yr
period from 2006 to 2008, the most recent years for which
electronic medical records were available at all the study sites
when the study was initiated in 2009.
Materials and Methods
is study meets the criteria for the Protection of Human
Subjects exemption 4 (research involving preexisting data) of
the U.S. Code of Federal Regulations (45 CFR 46.101). A
formal application was prepared and submitted to each of the
site institutional review boards (IRB) (Columbia University
Medical Center Institutional Review Board, New York, New
York; Saint Barnabas Medical Center Institutional Review
Board, Livingston, New Jersey; Northwestern University
Institutional Review Board, Chicago, Illinois; e Childrens
Hospital of Philadelphia Institutional Review Board, Phila-
delphia, Pennsylvania; New York University Langone Medi-
cal Center/School of Medicine Institutional Review Board,
New York, New York; University Health Network Research
Ethics Board, Toronto, Ontario, Canada), and the study was
either deemed exempt from full review by the IRB chair or
approved after review based on local IRB policies. Written
consent was waived by the IRB at all sites.
Design and Setting
For this multicenter study, hospital billing records with a
primary or secondary diagnosis of MH (ICD-9 995.86 or
ICD-10 T88.3) were identified at six academic medical
centers (Columbia University Medical Center and Morgan
Stanley Childrens Hospital, New York, New York; Saint
Barnabas Medical Center, Livingston, New Jersey; North-
western Memorial Hospital, Chicago, Illinois; Children’s
Hospital of Philadelphia, Philadelphia, Pennsylvania; New
York University Medical Center, New York, New York; Uni-
versity Health Network, Toronto, Ontario, Canada).
Study Population and Data Collection
e electronic databases from the participating hospitals
were searched to identify patients with the discharge diag-
nosis of MH (ICD-9 995.86 or ICD-10 T88.3) for a 3-yr
period, between January 1, 2006 and December 31, 2008.
For each identified hospitalization, the medical record was
reviewed including all notes, labs, and all available clini-
cal data from both paper and electronic sources. Other
hospitalizations for the same patient were not included in
the review.
e chart reviews were conducted by an expert panel
consisting of five anesthesiologists who are MH Hotline
consultants and have been trained in human subjects pro-
tection and the Health Insurance Portability and Account-
ability Act (Teeda Pinyavat, Henry Rosenberg, Cynthia A.
Wong, Sheila Riazi, Lena S. Sun). e records were anony-
mized by a nonpanelist coinvestigator or research coordina-
tor trained in privacy policies and practices prior to review
by the expert panel. Two panelists independently reviewed
each record and completed a standard data abstraction form
individually (appendix).
If, in the judgment of the panelist, an adverse metabolic
reaction occurred, the MH clinical grading scale (CGS) was
calculated.9 Although the CGS does rely on an anesthesi-
ologist’s judgment, it provides a validated means to quantify
and standardize the diagnosis. In addition to the CGS, the
likelihood of MH was classified as possible, probable or ful-
minant based on the expert panelist’s opinion. When there
was discrepancy between the two reviews, a third panelist
was assigned to reconcile the differences on site with the two
first panelists present to answer questions. When differences
did occur they were usually easily reconciled when informa-
tion missed by one panelist was found by another. ere
were no charts for which an agreement could not be made
on a final CGS score and assignment of MH probability by
three panelists.
Statistical Analysis
Proportions and confidence intervals (95%) were calculated
using Stata Version 11.2 (StataCorp LP, College Station, TX).
A total of 47 patients were discharged with a diagnosis of
MH as indicated by ICD-9 code 995.86 or ICD-10 code
T88.3 from the six participating hospitals between January
1, 2006 and December 31, 2008. Medical records for all 47
patients were reviewed. Of these 47 patients, 10 (21%) were
children (age 17 yr or less) and 23 (49%) were male. e
mean age was 40 yr and the median age was 36 yr. irty-
two of the patients (68.1%) were admitted for or under-
went a surgical procedure with general anesthesia during the
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Anesthesiology 2015; 122:55-63 57 Pinyavat et al.
MH Codes and Clinical MH Cases
Eleven of the 47 patients had an incident of possible, prob-
able, or fulminant MH event triggered by anesthesia during
the index hospitalization (table 1). erefore, the positive
predictive value for incident MH when MH was coded as a
primary or secondary discharge diagnosis was 23.4% (95%
CI (12.3–38.0%). MH was coded as the primary diagnosis
in one case. is patient was transferred from an outside hos-
pital for MH management.
e age range of the 11 patients with an incident of pos-
sible, probable, or fulminant MH was 4–77 yr. e mean
age was 33 yr and 66% were male. All patients had a sur-
gical procedure during the admission except for one who
was transferred from an ambulatory surgical center for MH
management after liposuction. Five of the 11 cases were
emergent. Succinylcholine was administered in 6 of the
11 cases. In one patient, the sole triggering agent received
was succinylcholine. e remaining 10 patients received
volatile halogenated agents, most often sevoflurane or des-
flurane. e maximum temperature ranged from 36.3° to
40.4°C with a mean of 38.7°C (temperature information
was not available for two patients). All patients survived
to discharge.
Nine patients received dantrolene. One patient who did
not receive dantrolene was a 4-yr-old boy who had masseter
spasm after succinylcholine. Volatile anesthetics were discon-
tinued and the patient was observed without further treat-
ment. e second patient who did not received dantrolene
was a 5-yr-old boy with congenital ptosis who had signs of
hypermetabolism (temperature of 38.2°C, heart rate of 165
beats/min, and an end tidal carbon dioxide of 60 mm Hg)
during an anesthetic that resolved after discontinuation of
volatile anesthetic, cooling, and hyperventilation.
MH Codes and Personal or Family History
Twenty-two patients (46.8%) were coded due to a personal
(n = 12) or family (n = 6) history of MH, or both (n = 4).
In the cases of family history, all except one were in a first-
degree relative.
MH Codes and Non-MH Cases
Eleven records were miscoded as MH due to a high fever
unrelated to anesthesia (maximum temperature ranged from
40.5° to 42.2°C with a mean of 41.5°C). e mean age was
40 yr; 36% were male, and 72% had no surgical procedure
or anesthesia during admission. In-hospital all-cause mortal-
ity for these patients was 18%.
Dantrolene was administered in three cases determined
not to be related to MH and miscoded due to fever. One
patient was a 55-yr-old male with a history of traumatic brain
injury admitted from a rehabilitation facility with fever and
a diagnosis of urosepsis. Dantrolene was “given empirically
for his fever of 41.1°C and MH was listed on the differential
diagnosis in an emergency department note. Another patient
was a 91-yr-old female with heart failure, chronic obstructive
pulmonary disease, and renal insufficiency admitted with
pneumonia. She had received haloperidol, and dantrolene
was given due to suspected neuroleptic malignant syndrome
with a maximum temperature of 41.3°C. e third patient
was a 2-yr-old female with severe pulmonary hypertension
who became unstable after receiving epoprostenol. Upon
arrival in the intensive care unit, dantrolene and antibiotics
were given for a fever of 41.1°C.
e remaining three non-MH cases had no clear expla-
nation for miscoding. Two were oncology patients. One
was a 75-yr-old male with hairy cell leukemia admitted for
osteomyelitis and possible infected spinal hardware with a
maximum temperature of 37.5°C. e second patient was
a 69-yr-old female with breast cancer admitted for breast
lumpectomy and no recorded fever. e third patient was a
32-yr-old female with no recorded fever who had a respira-
tory arrest 2 h after a lumbar decompression and fusion pos-
sibly due to opioid overdose.
MH Codes for Surgical Cases and Patients
Receiving Dantrolene
A total of 32 patients who underwent a surgical procedure
with general anesthesia, 11 were judged to have a clinical MH
event (34.3%) and 16 had personal or family history of MH
(50%). A total of 12 patients who were given dantrolene, 9
(75%) had a clinical MH event, none had a history or family
history of MH, and 3 (25%) had an event unrelated to MH.
In patients who had surgery and dantrolene, 9 out of 10 had
an incident MH event.
Our results show that of 47 patients with ICD-9 or ICD-10
coded MH on hospital discharge, 23.4% had an incident
MH episode and 46.8% a personal and/or family history of
Table 1. Explanation for Malignant Hyperthermia Code for
Total Sample
Frequency (n) %
MH incident 11 23.4%
Possible 4
Probable 4
Fulminant 3
MH history 22 46.8%
Patient 12
Family 6
Patient and family 4
Fever* unrelated to MH 11 23.4%
Other† 3 6.3%
Total 47
*Fever dened as maximum temperature greater than 37.5 °C. †Other
includes cases of infected spinal hardware without fever, lumpectomy for
breast mass without complication, and lumbar decompression and fusion
complicated by postoperative respiratory arrest.
MH = malignant hyperthermia.
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Anesthesiology 2015; 122:55-63 58 Pinyavat et al.
Accuracy of ICD Code for “Malignant Hyperthermia”
MH. Taken together, approximately 70% of cases were MH
susceptible. e most common reason for inaccurate coding
was high fever unrelated to anesthesia.
We were broad in our inclusion of all suspected cases,
from possible to fulminant, as true positives for the ICD
code. While this broad definition may have increased our
estimate of coding accuracy, we believe most researchers
using the ICD code to investigate MH are interested in any
possible cases rather than being limited to biopsy-proven
MH. Although we analyzed them separately, we did not
consider the personal and/or family history cases as coded
in error. In some ways, MH susceptibility can be viewed as
a chronic disease. Having a positive history or family history
has important clinical implications and the diagnosis should
be carried through the medical record on each admission.
However, because a different ICD diagnosis of MH suscep-
tibility does not exist, the diagnosis of MH is assigned in
these cases.
Our study found that a personal or family history of
malignant hyperthermia is difficult to distinguish from an
incident diagnosis using discharge diagnoses alone. Some
databases such as Medicaid and Medicare databases, and
individual state hospital discharge databases, contain a “pres-
ent on admission” flag to identify a preexisting condition.
In our previous study on MH prevalence in New York State
between 2001 and 2005, 52% (38 of 73) of cases with the
MH diagnosis were flagged as having the condition present
on admission.2 We found in the current study that 47% of
cases with the MH diagnosis were coded due to personal or
family history of MH. e results and conclusions of previ-
ous studies of MH prevalence using administrative databases
may be impacted by our finding that prevalence of MH
susceptibility is more likely to be accurately captured by
ICD code than MH incidence. e confusion in coding the
patient as MH susceptible versus having had an acute MH
event may also impact medical billing and reimbursement,
arguably the most important use of ICD codes today.
Including only surgical admissions increased the posi-
tive predictive value of the MH code for incident MH from
23.4% to 34.4%. Most of the patients with a suspected MH
event received dantrolene. erefore, one way to improve
specificity of searches for incident MH events using adminis-
trative databases might be to include information on whether
a surgical procedure was performed and whether dantrolene
was administered.
Many ICD coding accuracy studies use physician diagno-
sis in the medical record or expert coders reabstraction of the
record as a gold standard.5,7,8,10 ey address coding accu-
racy and assume physician accuracy.7 A definitive diagnosis
of MH is often problematic to make over the course of one
hospitalization. While muscle biopsy and caffeine-halothane
contracture testing can be performed at special testing cen-
ters to confirm MH susceptibility, there is no test that can
be applied acutely to distinguish MH from other causes of
hypermetabolism or hyperthermia. Moreover, contracture
tests are not reliable if performed in the first three months
after an acute event and therefore these results are not avail-
able during the same hospital admission, if at all. Many stud-
ies in the United States and Europe have used the CGS as
the clinical definition for MH.1,11,12 We chose the CGS and
expert opinion as our standard for true MH occurrence. In
choosing this external gold standard, we attempted to mini-
mize the amount of physician error. For instance, in two of
the three “non-MH” cases in which dantrolene was given,
MH was perhaps on the treating physicians differential diag-
nosis but was deemed highly unlikely by our expert panel.
Validating the physicians’ notes in the instance of reported
previous personal or family history of MH, however, was
beyond the scope of the study.
Coding errors for MH accounted for approximately
32% of cases, most often involving patients with high
fever. Because the introduction of the MH code occurred
first in October 1997, familiarity with MH may be low
among medical coders.11 We also found that it was fairly
common for physicians to inappropriately use the term
“malignant hyperthermia”—perhaps reflecting the ambi-
guity of the terminology that currently exists—to refer
to this hypermetabolic syndrome that is neither malig-
nant nor always hyperthermic. Patients with fever who
were mistakenly coded with MH tended to have a higher
maximum temperature than patients who had a true MH
episode. ey were sicker overall than patients who had a
true MH episode with most patients having an American
Society of Anesthesiologists Physical Status of 3 or greater
and a high mortality rate. ey were also unlikely to have
had a surgical procedure or anesthesia or to have received
dantrolene. Excluding patients with diagnoses associated
with hyperthermia, such as sepsis and neuroleptic malig-
nant syndrome, as Rosero et al.4 did in their study of MH
using the Nationwide Inpatient Sample, would eliminate
many of these coding errors.
Sequencing errors were studied widely when diagnosis-
related groups became the basis for hospital reimbursement.
e order of primary versus secondary diagnosis in these
studies was found be highly prone to error.5,10,13 e Insti-
tute of Medicine study found sequencing to be the num-
ber one reason for coding errors, leading to over 80% of
errors made in coding ischemic heart disease, for example.10
To minimize the impact of type of error and find as many
cases as possible for review, we included both primary and
secondary diagnoses of MH. e primary diagnosis is often
based on the admitting diagnosis and acute MH will usually
not appear as the admitting diagnosis, with the exception
of patient transfer for MH management. Including MH
as only a primary diagnosis would have missed all but one
admission in our study.
Limitations of our study include a small study sample
and a limited number of institutions. Our study was also
limited by the inability to identify cases in which the MH
code was omitted. erefore, we are unable to report a code
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Anesthesiology 2015; 122:55-63 59 Pinyavat et al.
specificity or sensitivity. Further studies of MH ICD code
accuracy might be of interest based on a larger sample of
hospitals, including both academic medical centers and
ambulatory surgical centers. Comparing MH ICD coding
accuracy in the United States and other countries would
also be of interest.
To our knowledge, this is the first study to examine the
ICD code for MH due to anesthesia. We estimate that the
code has a positive predictive value of approximately 23.4%
(95% CI, 12.3–38.0%) for incident MH, and 70.2% (95%
CI, 55.1–82.7%) for MH susceptibility. e code is more
likely to detect a history or family history of MH (47%)
than an incident MH event. e remainder of the cases were
miscoded, many due to high fever. Possible barriers unique
to accuracy of ICD coding for MH include variable clinical
presentation, lack of a pathognomonic test, rarity of the dis-
ease leading to inexperience among physicians and coders,
and relative newness of the code.
Using the vast amount of data available through admin-
istrative databases is important in expanding our knowledge
for rare diseases such as MH. It may be possible to improve
accuracy in finding MH events, if additional information
such as Current Procedural Terminology (CPT) billing codes
or Clinical Classification Software (CCS) procedure codes
are used to confirm that a surgical procedure took place, and
anesthesia was given during the admission; pharmacy data-
bases may be used to confirm that dantrolene was adminis-
tered. Further study is required to find the best algorithm of
codes to accurately capture incident MH cases in hospital
discharge records. Educating physicians and medical coders
about MH should also help increase coding accuracy.
The authors thank Anthony Isenalumhe, M.D., and Thom-
as Blanck, Ph.D., M.D., of the Department of Anesthesi-
ology, New York University, New York, New York, and
Ronald Litman, D.O., and Theodora Goebel, R.N., V.S.N.,
at the Department of Anesthesiology, Children’s Hospital
of Philadelphia, Philadelphia, Pennsylvania, for their as-
sistance with site chart reviews.
This study was supported in part by the Malignant Hy-
perthermia Association of the United States, Sherburne,
New York.
Competing Interests
Dr. Rosenberg received a one-time speaking fee from Eagle
Pharmaceuticals (Woodcliff Lake, New Jersey), a company
which manufactures Ryanodex, a concentrated formula-
tion of dantrolene approved for the treatment of malignant
hyperthermia. The other authors declare no competing in-
Address correspondence to Dr. Li: Departments of Anes-
thesiology and Epidemiology, Columbia University College
of Physicians and Surgeons and Mailman School of Public
Health, 622 West 168th St., PH5-505, New York, New York
10032. Information on pur-
chasing reprints may be found at
or on the masthead page at the beginning of this issue.
ANESTHESIOLOGY’S articles are made freely accessible to all
readers, for personal use only, 6 months from the cover
date of the issue.
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Accuracy of ICD Code for “Malignant Hyperthermia”
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Appendix. (Continued)
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Accuracy of ICD Code for “Malignant Hyperthermia”
Appendix. (Continued)
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Anesthesiology 2015; 122:55-63 63 Pinyavat et al.
Appendix. (Continued)
AE = adverse event; ALT = alanine transaminase; AMR = adverse metabolic reaction; Anesth. = anesthetic; Art/Ven = arterial/venous; ASC = ambulatory
surgery center; AST = aspartate transaminase; BE = base excess; BPM = beats per minute; CK = creatinine kinase; CPR = cardiopulmonary resuscitation;
CPT = Current Procedural Terminology; DIC = disseminated intravascular coagulopathy; ET = endotracheal; ETCO2 = end-tidal carbon dioxide; ETPCO2 =
end-tidal partial carbon dioxide concentration; F = female; FiO2 = fraction of inspired oxygen; GI = gastrointestinal; HR = heart rate; I = initial reaction; ICU
= intensive care unit; IRB = institutional review board; IV = intravenous; K = potassium; M = male; Max. = maximum; MH = malignant hyperthermia; Min. =
minimum; MM/YYYY = month/year; N = no; N/A = not applicable; N/D = not determined; PaCO2 = arterial carbon dioxide tension; pCO2 = partial pressure
of carbon dioxide; PetCO2 = end-tidal pressure of carbon dioxide; pO2 = partial pressure of oxygen; PPV = positive predictive value; pt = paties; R = recru-
descence; Rx = reaction; SIDS = sudden infant death syndrome; Temp. = temperature; UNK = unknown; Y = yes; yr = years.
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... While the confirmation of the diagnosis is still pending, the patient's medical record mentions a high suspicion of MH susceptibility and subsequent treatment with dantrolene. The inability to rapidly confirm a diagnosis or even perform the gold-standard biopsy test in a single hospital admission can result in suspected or inaccurately diagnosed cases ending up as a preexisting condition in a patient's permanent medical record [4]. Denial of insurance coverage, exorbitant premiums, and discrimination based on preexisting conditions has garnered enough attention to result in various legislative protections, but the risk of repeal 2 Case Reports in Anesthesiology of current policies and implementation of new healthcare campaigns may have profound effects on the affordability or eligibility of insurance for patients who carry the diagnosis of MH. ...
... In conclusion, making a clinical diagnosis of MH can be problematic and confirmation of the disease is cumbersome and not usually possible on a single admission. There is no test that can be applied acutely to distinguish MH from other causes of hypermetabolism or hyperthermia [4]. The symptoms may occur at any time during the perioperative period and can be highly variable. ...
... The benefits of using dantrolene with our patient certainly outweighed the risks, resulting in a favorable outcome, but such prudent clinical decisions may have longlasting effects. Pinyavat et al. explain that miscoding for MH, preemptively treating suspicious cases with dantrolene (as with our case), and even simply having a family member with the disease have contributed to a significant number of cases being added to Medicaid and Medicare databases, as well as individual state hospital discharge databases, listing MH as "present on admission," and have resulted in MH being identified as a preexisting condition [4]. Without confirmation via the caffeine-halothane contracture test, we will never be certain of the diagnosis with our patient. ...
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The purpose of this case report is to increase awareness that a diagnosis of malignant hyperthermia may have long-lasting or permanent effects on a patient’s insurance eligibility or premiums despite legislation providing varying levels of protection from preexisting conditions or genetic discrimination. We present a case of severe rigors, unexplained severe metabolic acidosis, and severe hyperthermia in a patient after general anesthesia for extensive head and neck surgery. The patient was treated for malignant hyperthermia and demonstrated a significant clinical improvement with the administration of dantrolene. Even with an “almost certain” diagnosis of malignant hyperthermia by clinical presentation, genetic testing was negative and the gold-standard caffeine-halothane contracture test has yet to be performed. Laboratory results, clinical grading scales, and genetic testing support a diagnosis of malignant hyperthermia but the gold standard is a live muscle biopsy and caffeine-halothane contracture test. A clinical diagnosis of MH or a positive caffeine-halothane contracture test could result in exclusion from genetic discrimination legislature due to the fact that diagnosis can be confirmed without genetic testing. The fate of the Affordable Care Act may also affect how insurance companies scrutinize this disease. Improving accuracy of MH diagnosis in hospital discharge records will be crucial.
... It is both desirable and sensible to add a separate code for MH history or susceptibility to the ICD system. Before the coding for MH is refined, a useful approach to differentiate incident MH cases from patients with MH susceptibility is to review medical charts for patients with a recorded diagnosis of MH in combination with ICD codes [28]. Also, additional codes for detailed information on anesthesia such as administration of dantrolene during surgical procedures could be added to the SID as this would help differentiate incident MH cases from MH susceptibility diagnosis. ...
... Second, the accuracy and completeness of MH diagnosis and coding may vary across hospitals and states. Based on a recent study, the most common reason for inaccurate MH coding for hospital discharge records is due to high fever unrelated to anesthesia [28]. The study also finds that prevalence of MH susceptibility is more likely to be captured accurately by ICD-9-CM code than MH incidence [28], implying that by using administrative databases such as the SIDs, the MH prevalence found in our study could be reflecting a higher proportion of MH susceptible cases rather than MH incidence. ...
... Based on a recent study, the most common reason for inaccurate MH coding for hospital discharge records is due to high fever unrelated to anesthesia [28]. The study also finds that prevalence of MH susceptibility is more likely to be captured accurately by ICD-9-CM code than MH incidence [28], implying that by using administrative databases such as the SIDs, the MH prevalence found in our study could be reflecting a higher proportion of MH susceptible cases rather than MH incidence. ...
Study objective: Malignant hyperthermia (MH) is a rare yet potentially fatal pharmacogenetic disorder triggered by exposure to inhalational anesthetics and the depolarizing neuromuscular blocking agent succinylcholine. Epidemiologic data on the geographic variation in MH prevalence is scant. The objective of this study is to examine the prevalence of recorded MH diagnosis in patients discharged from hospitals in four states in the United States. Design: Observational study. Setting: Healthcare Cost and Utilization Project (HCUP) State Inpatient Database (SID) for California (2011), Florida (2011), New York (2012) and Wisconsin (2012). Patients: A total of 164 hospital discharges that had a recorded diagnosis of MH using the International Classification of Disease, 9th Revision, Clinical Modification code 995.86. Methods: MH prevalence was assessed by patient demographic and clinical characteristics. Main results: The prevalence of MH per 100,000 hospital discharges ranged from 1.23 (95% Confidence Interval [CI], 0.80-1.66) in New York to 1.91 (95% CI, 1.48-2.34) in California, and the prevalence of MH per 100,000 surgical discharges ranged from 1.47 (95% CI, 0.93-2.02) in New York to 2.86 (95% CI, 2.00-3.71) in Florida. The prevalence of MH in male patients was more than twice the prevalence in female patients. Of the 164 patients with MH diagnosis, 11% were dead on discharge. Conclusions: There exists a modest variation in the prevalence of recorded MH diagnosis in hospital discharges in California, Florida, New York and Wisconsin. Epidemiologic patterns of MH diagnosis in hospital discharges appear to be similar across the four states. Further research is needed to better understand the geographic variation and contributing factors of MH in different populations.
... However, the true incidence of MH episodes in hospital is uncertain as the accuracy of discharge records which have been used to identify MH cases has been questioned [8]. For example, in a recent report of hospital billing records in which patients with a discharge diagnosis of MH were identified, only 23.4% had a likely MH episode while 23.4% had hyperthermia attributed to other causes when their medical records were reviewed by an expert panel of anesthesiologists [9]. MH is inherited in an autosomal dominant pattern with susceptibility linked primarily to the RYR1 gene [4]. ...
... The apparently similar mortality with or without dantrolene may be explained by the likelihood that mortality was reduced by dantrolene in patients who met criteria for MH, whereas mortality was also low in patients for whom dantrolene was not prescribed because their symptoms were not severe enough to meet threshold criteria for MH and warrant dantrolene treatment [7], or because their MH-like episodes were misdiagnosed and actually were caused by other syndromes treated with alternative measures. A previous study suggested that only one fourth of cases recorded as MH in hospital records represented true MH cases, whereas an equal number were attributed to other conditions [8,9]. In our study, a secondary subgroup inspection of individual medical records of MH patients who received dantrolene revealed that 7/13 (53.8%) were "somewhat greater than likely" to meet standardized criteria for a definite MH episode [44], compared with only 1/19 (5.26%) patients coded as having MH who did not receive dantrolene. ...
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Background Intravenous dantrolene is often prescribed for hypermetabolic syndromes other than the approved indication of malignant hyperthermia (MH). To clarify the extent of and indications for dantrolene use in conditions other than MH, we sought to document current practices in the frequency, diagnoses, clinical characteristics and outcomes associated with dantrolene treatment in critical care settings. Methods Inpatients receiving intravenous dantrolene from October 1, 2004 to September 30, 2014 were identified retrospectively in the U.S. Veterans Health Administration national database. Extracted data included; diagnoses of hypermetabolic syndromes; triggering drugs; dantrolene dosages; demographics; vital signs; laboratory values; in-hospital mortality; complications; and lengths of stay. Frequency and mortality of patients who did not receive dantrolene were obtained in selected diagnoses for exploratory comparisons. Results Dantrolene was administered to 304 inpatients. The most frequent diagnoses associated with dantrolene treatment were neuroleptic malignant syndrome (NMS; N = 108, 35.53%) and sepsis ( N = 47, 15.46%), with MH accounting for only 13 (4.28%) cases. Over half the patients had psychiatric comorbidities and received psychotropic drugs before dantrolene treatment. Common clinical findings in patients receiving dantrolene included elevated temperature (mean ± SD; 38.7 ± 1.3 °C), pulse (116.33 ± 22.80/bpm), respirations (27.75 ± 9.58/min), creatine kinase levels (2,859.37 ± 6,646.88 IU/L) and low pO 2 (74.93 ± 40.16 mmHg). Respiratory, renal or cardiac failure were common complications. Mortality rates in-hospital were 24.01% overall, 7.69% in MH, 20.37% in NMS and 42.55% in sepsis, compared with mortality rates in larger and possibly less severe groups of unmatched patients with MH (5.26%), NMS (6.66%), or sepsis (41.91%) who did not receive dantrolene. Conclusions In over 95% of cases, dantrolene administration was associated with diagnoses other than MH in critically-ill patients with hypermetabolic symptoms and medical and psychiatric comorbidities. Exploratory survey data suggested that the efficacy and safety of dantrolene in preventing mortality in hypermetabolic syndromes other than MH remain uncertain. However, randomized and controlled studies using standardized criteria between groups matched for severity are essential to guide practice in using dantrolene.
... Second, identification of MH diagnosis relies on the accuracy of coding in discharges data and is susceptible to misclassification because of error or absence of coding. In a previous study evaluating the accuracy of MH diagnosis in hospital discharge records, we found that the ICD-9-CM code 995.86 ("Malignant hyperthermia due to anesthesia") corresponded to a MH crisis in 24% of the cases, to a MH history in 47%, and to fever unrelated to MH in 24% [25]. Therefore, most of the cases with an MH diagnosis identified in the present study should be regarded as MH susceptibility rather than incident MH episodes. ...
... However, a general anesthetic may be required after a vaginal delivery in some circumstances such as the removal of a retained placenta or an exploration of the uterine cavity because of a postpartum hemorrhage. Moreover, as indicated in our previous study, most of the MH diagnoses in hospital discharge records refer to positive MH history and susceptibility rather than acute MH episodes [25]. These two factors may explain why the prevalence of MH diagnosis in vaginal delivery was much lower than in cesarean delivery (0.29 per 100,000 versus 0.81 per 100,000. ...
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Background: The cost-benefit of stocking dantrolene in maternity units for treating malignant hyperthermia (MH) has been recently questioned because of the low incidence of MH crisis in the general population and the low utilization of general anesthesia in obstetrics. However, no study has examined the prevalence of MH susceptibility in obstetrics. This study aimed to assess the prevalence of MH diagnosis and associated factors in obstetric patients. Methods: Data for this study came from the National Inpatient Sample from 2003 to 2014, a 20% nationally representative sample of discharge records from community hospitals. A diagnosis of MH due to anesthesia was identified using the International Classification of Diseases, Ninth Revision, Clinical Modification code 995.86. MH prevalence was estimated according to the delivery mode and patient and hospital characteristics. Results: During the 12-year study period, 47,178,322 delivery-related discharges [including 15,175,127 (32.2%) cesarean deliveries] were identified. Of them, 215 recorded a diagnosis of MH, yielding a prevalence of 0.46 per 100,000 [95% confidence interval (CI), 0.40 to 0.52]. The prevalence of MH diagnosis in cesarean deliveries was 0.81 per 100,000 (95% CI, 0.67 to 0.97), compared with 0.29 per 100,000 (95% CI, 0.23 to 0.35) in vaginal deliveries (P < 0.001). Multivariable logistic regression revealed that cesarean delivery was associated with a significantly increased risk of MH diagnosis [adjusted rate ratio (aOR) 2.88; 95% CI, 2.19 to 3.80]. Prevalence of MH diagnosis was lower in Hispanics than in non-Hispanic whites (aOR 0.47; 95% CI, 0.29 to 0.76) and higher in the South than in the Northeast census regions (aOR 2.44; 95% CI, 1.50 to 3.96). Conclusion: The prevalence of MH-susceptibility is about 1 in 125,000 in cesarean deliveries, similar to the prevalence reported in non-obstetrical surgery inpatients. The findings of this study suggest that stocking dantrolene in maternity units is justified.
... To our knowledge, there are no pediatric studies of aspiration to date which employ secondary data sources to enhance capture of cases of aspiration, as well as no studies to assess the validity of ICD-9 coding of perioperative aspiration either in children or adults. 19 The large-scale studies of perioperative aspiration to date have been performed in various populations. Three studies were performed in mixed cohorts of adults and children, 2 exclusively in adults, and 6 focused specifically on children. ...
... While other ICD-9-coded adverse events have been evaluated, validation of the accuracy of ICD-9 codes for aspiration has not yet been performed. 19,20 In our population of children who received anesthesia, the positive predictive value (PPV) of the 507.0 (pneumonitis due to inhalation of food or vomitus) ICD-9 code was high (95%) for recognizing aspiration at some point during the hospitalization (including patients with aspiration as a reason for admission). However, when used to identify perioperative aspiration in this cohort, the PPV of the code was low (3.5%). ...
Background: Perioperative aspiration is a rare but potentially devastating complication, occurring in 1-10 per 10 000 anesthetics based on studies of quality assurance databases. Quality assurance reporting is known to underestimate the incidence of adverse outcomes, but few large studies use supplementary data sources. This study aims to identify the incidence of and risk factors for perioperative aspiration in children using quality assurance data supplemented by administrative billing records, and to examine the utility of billing data as a supplementary data source. Methods: Aspiration events for children receiving anesthesia at a tertiary care pediatric hospital between 2008 and 2014 were identified using (i) a perioperative quality assurance database and (ii) hospital administrative billing records with International Classification of Diseases, Ninth Revision Clinical Modification coded diagnoses of aspiration. Records were subject to review by pediatric anesthesiologists. Following identification of all aspiration events, the incidence of perioperative aspiration was calculated and risk factors were assessed. Results: 47 272 anesthetic cases were evaluated over 7 years. The quality assurance database identified 20 cases of perioperative aspiration occurring in surgical inpatients, same-day admissions, and outpatients. Using hospital administrative data (which excludes outpatients with shorter than a 24-hour stay), 9 cases of perioperative aspiration were identified of which 6 had not been found through quality assurance data. Overall, International Classification of Diseases, Ninth Revision coding demonstrated a positive predictive value of 94.5% for any aspiration event; however, positive predictive value was <4% for perioperative aspiration. A total incidence of 5.5 perioperative aspirations per 10 000 (95% CI: 3.7-8.0 per 10 000) anesthetics was found. Conclusion: Quality assurance data offer an efficient way to measure the incidence of rare events, but may underestimate perioperative complications. International Classification of Diseases, Ninth Revision codes for aspiration used as a secondary data source were nonspecific for perioperative aspiration, but when combined with record review yielded a 30% increase in identified cases of aspiration over quality assurance data alone. The use of administrative data therefore holds potential for supplementing quality assurance studies of rare complications.
... In fact, hospital discharge codes from administrative data are extensively used for studying the epidemiology of a plethora of diseases and conditions and have substantial impact on epidemiological estimates [10]. For this reason, much research is being conducted to assess their accuracy [11][12][13][14][15][16]. ...
Objective: To assess the sensitivity of hospital discharge diagnoses for identifying sepsis in patients with blood culture confirmation. Methods: A cross-sectional study was conducted at the Italian 1000-bed University Hospital of Udine. The administrative databases of the Hospital were used as the source of information. Laboratory data were linked with hospital discharge data. We estimated the proportion of hospitalizations with at least 2 positive blood culture tests in which at least one discharge diagnosis indicated bloodstream infection. Results: From 2011 to 2017, 3571 hospitalizations (1.2%) had positive blood culture tests. Of them, only 49.5% had at least one ICD-9-CM discharge diagnosis code of sepsis, with lower proportions in surgical than in medical wards. Conclusions: The sensitivity of ICD-9-CM discharge codes for sepsis is low as compared with the blood culture gold standard. Using discharge codes for epidemiological estimates of sepsis, health planning and risk management may yield biased results. Audits and ICD coding training are needed.
... Although ear, nose, and throat procedures seem to be the most common reason for surgery in the majority of MH cases in children, 2,44 orthopedic surgery and other emergent procedures are preponderant among adults. 29,41,45 Anecdotal reports of MH occurring during or shortly after emergent surgery for acute appendicitis are not rare in the medical literature. [46][47][48][49][50][51][52][53][54] It seems thus reasonable to suggest that a 10-to 20-fold increased risk of MH secondary to succinylcholine use 42,43 might not be solely attributable to the effects of the drug on the intracellular calcium dynamics of genetically predisposed patients, but also to a threshold shift induced by fever or a concomitant inflammatory process like sepsis or trauma, priming the onset of MH. ...
What we already know about this topic: Malignant hyperthermia is a rare life-threatening disorder triggered in genetically predisposed individuals by exposure to certain anestheticsThe ryanodine receptor 1 (RYR1) gene, which encodes the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum, is the major malignant hyperthermia-associated locusMalignant hyperthermia diagnostic mutations are more prevalent than the reported incidence of clinical malignant hyperthermia episodes because many mutation carriers are never exposed to anesthetic triggers and some may have several uneventful anesthetics before developing malignant hyperthermia reaction WHAT THIS ARTICLE TELLS US THAT IS NEW: In a multicenter case-control study of 229 genotype-positive subjects with previous recorded exposure to trigger anesthetics, there were 93 malignant hyperthermia cases, for an overall penetrance for the analyzed RYR1 mutations of 40.6%The probability of developing malignant hyperthermia on exposureto triggers was 0.25 among all RYR1 mutation carriers and 0.76 in survivors of malignant hyperthermia reactions (95% CI of the difference 0.41 to 0.59)Young age, male sex, and the use of succinylcholine were major nongenetic risk factors influencing expression of the RYR1 mutations conferring malignant hyperthermia susceptibility BACKGROUND:: Malignant hyperthermia (MH) is a potentially lethal disorder triggered by certain anesthetics. Mutations in the ryanodine receptor 1 (RYR1) gene account for about half of MH cases. Discordance between the low incidence of MH and a high prevalence of mutations has been attributed to incomplete penetrance, which has not been quantified yet. The authors aimed to examine penetrance of MH-diagnostic RYR1 mutations and the likelihood of mutation carriers to develop MH, and to identify factors affecting severity of MH clinical expression. Methods: In this multicenter case-control study, data from 125 MH pedigrees between 1994 and 2017 were collected from four European registries and one Canadian registry. Probands (survivors of MH reaction) and their relatives with at least one exposure to anesthetic triggers, carrying one diagnostic RYR1 mutation, were included. Penetrance (percentage of probands among all genotype-positive) and the probability of a mutation carrier to develop MH were obtained. MH onset time and Clinical Grading Scale score were used to assess MH reaction severity. Results: The overall penetrance of nine RYR1 diagnostic mutations was 40.6% (93 of 229), without statistical differences among mutations. Likelihood to develop MH on exposure to triggers was 0.25 among all RYR1 mutation carriers, and 0.76 in probands (95% CI of the difference 0.41 to 0.59). Penetrance in males was significantly higher than in females (50% [62 of 124] vs. 29.7% [30 of 101]; P = 0.002). Males had increased odds of developing MH (odds ratio, 2.37; 95% CI, 1.36 to 4.12) despite similar levels of exposure to trigger anesthetics. Proband's median age was 12 yr (interquartile range 6 to 32.5). Conclusions: Nine MH-diagnostic RYR1 mutations have sex-dependent incomplete penetrance, whereas MH clinical expression is influenced by patient's age and the type of anesthetic. Our quantitative evaluation of MH penetrance reinforces the notion that a previous uneventful anesthetic does not preclude the possibility of developing MH.
... Local anesthetic systemic toxicity is a rare event and as such may be more susceptible to inappropriate ICD-9-CM coding as for malignant hyperthermia. 22 Furthermore, in our study, most discharges with a diagnosis of LASTwere classified as unknown and did not contain an associated manifestation of LAST such as seizure or cardiac complication. However, previous studies have used these ICD-9-CM codes to identify a diagnosis of LAST. ...
Background: Local anesthetic systemic toxicity (LAST) is a rare and potentially devastating complication of regional anesthesia. Single-institution registries have reported a decreasing incidence, but these results have limited broad applicability. A recent study using a US database found a relatively high incidence of LAST. We used the National Inpatient Sample, a US database of inpatient admissions, to identify the national incidence and associated risk factors for LAST in total joint arthroplasties. Methods: In this retrospective study, we studied patients undergoing hip, knee, or shoulder arthroplasty, from 1998 to 2013, with an adjunct peripheral nerve blockade. We used a multivariable logistic regression to identify patient conditions, hospital level variables, and procedure sites associated with LAST. Results: A total of 710,327 discharges met inclusion criteria. The average adjusted incidence was 1.04 per 1000 peripheral nerve blocks, with decreasing trend over the 15-year study period (odds ratio [OR], 0.90; P = 0.002). Shoulder arthroplasty (OR, 4.35; P = 0.0001) compared with knee or hip arthroplasty and medium-size (OR, 3.34; P = 0.003) and large-size (OR, 2.40; P = 0.025) hospitals as compared with small hospitals were associated with increased odds of LAST. Conclusions: The incidence of LAST nationally in total joint arthroplasty with adjunct nerve blocks is similar to recent estimates from academic centers, with a small decreasing trend through the study period. Despite an overall low incidence rate, practitioners should continue to maintain vigilance for manifestations of LAST, especially as the use of regional anesthesia continues to increase.
Malignant hyperthermia (MH) syndrome is an unusual disorder. Much like an individual who has an allergy, the MH-susceptible patient is often unaware of his or her problem unless there is a family history of anesthesia-related problems that suggest MH or until exposed to the “triggering” agent. MH syndrome may not develop on all exposures. The resemblance to an allergy breaks down, however, on further analysis. MH is an inherited disorder [1]. Patients develop a hypermetabolic condition on exposure to drugs that are generally used to produce general anesthesia such as isoflurane, halothane, desflurane, and sevoflurane or skeletal muscle paralysis, namely, succinylcholine [2]. The pathophysiologic change in MH relates to an uncontrolled increase of intracellular calcium in skeletal muscle that leads to hypermetabolism, depletion of energy sources, acidosis, and membrane breakdown [1–3]. Untreated, MH syndrome is fatal in most cases. With prompt discontinuation of trigger agents and administration of the drug dantrolene [4], mortality may be close to zero [5]. This chapter discusses clinical presentation, pathophysiology, molecular genetics, diagnosis, treatment, and sources of information for this unusual cause of anesthetic morbidity and mortality.
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We analyzed cases of malignant hyperthermia (MH) reported to the North American MH Registry for clinical characteristics, treatment, and complications. Our inclusion criteria were as follows: AMRA (adverse metabolic/musculoskeletal reaction to anesthesia) reports between January 1, 1987 and December 31, 2006; "very likely" or "almost certain" MH as ranked by the clinical grading scale; United States or Canadian location; and more than one anesthetic drug given. An exclusion criterion was pathology other than MH; for complication analysis, patients with unknown status or minor complications attributable to dantrolene were excluded. Wilcoxon rank sum and Pearson exact chi(2) tests were applied. A multivariable model of the risk of complications from MH was created through stepwise selection with fit judged by the Hosmer-Lemeshow statistic. Young males (74.8%) dominated in 286 episodes. A total of 6.5% had an MH family history; 77 of 152 patients with MH reported >or=2 prior unremarkable general anesthetics. In 10 cases, skin liquid crystal temperature did not trend. Frequent initial MH signs were hypercarbia, sinus tachycardia, or masseter spasm. In 63.5%, temperature abnormality (median maximum, 39.1 degrees C) was the first to third sign. Whereas 78.6% presented with both muscular abnormalities and respiratory acidosis, only 26.0% had metabolic acidosis. The median total dantrolene dose was 5.9 mg/kg (first quartile, 3.0 mg/kg; third quartile, 10.0 mg/kg), although 22 patients received no dantrolene and survived. A total of 53.9% received bicarbonate therapy. Complications not including recrudescence, cardiac arrest, or death occurred in 63 of 181 patients (34.8%) with MH. Twenty-one experienced hematologic and/or neurologic complications with a temperature <41.6 degrees C (human critical thermal maximum). The likelihood of any complication increased 2.9 times per 2 degrees C increase in maximum temperature and 1.6 times per 30-minute delay in dantrolene use. Elevated temperature may be an early MH sign. Although increased temperature occurs frequently, metabolic acidosis occurs one-third as often. Accurate temperature monitoring during general anesthetics and early dantrolene administration may decrease the 35% MH morbidity rate.
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Health care databases provide a widely used source of data for health care research, but their accuracy remains uncertain. We analyzed data from the 1985 National DRG Validation Study, which carefully reabstracted and reassigned ICD-9-CM diagnosis and procedure codes from a national sample of 7050 medical records, to determine whether coding accuracy had improved since the Institute of Medicine studies of the 1970s and to assess the current coding accuracy of specific diagnoses and procedures. We defined agreement as the proportion of all reabstracted records that had the same principal diagnosis or procedure coded on both the original (hospital) record and on the reabstracted record. We also evaluated coding accuracy in 1985 using the concepts of diagnostic test evaluation. Overall, the percentage of agreement between the principal diagnosis on the reabstracted record and the original hospital record, when analyzed at the third digit, improved from 73.2% in 1977 to 78.2% in 1985. However, analysis of the 1985 data demonstrated that the accuracy of diagnosis and procedure coding varies substantially across conditions. Although some diagnoses and all major surgical procedures that we examined were accurately coded, the variability in the accuracy of diagnosis coding poses a problem that must be overcome if claims-based research is to achieve its full potential.
The Veterans Administration's discharge abstract system was studied to identify error frequency, source, and effect in five Veterans Administration hospitals. We reviewed 1,829 medical records from 21 services for concordance with the abstract; sampling provided 95% confidence for each service. Of these records, 1,499 (82%) differed from the abstract in at least one item. Of 20,260 items, 4,360 (22%) were incorrect, with three error sources: physician (62%), coding (35%), and keypunch (3%). We projected 2.14 physician and 0.81 coding errors in the average abstract. Eighty-nine percent of projected physician errors were failures to report a procedure or diagnosis. Coding was subjective and errors were synergistic with physician errors. We projected that correction of errors would change 19% of the records for diagnosis-related group purposes and substantially increase future resource allocation. This effect varied considerably by service. (JAMA 1985;254:1330-1336)
Background: Determination of sensitivity and specificity of the in vitro contracture test (IVCT) for malignant hyperthermia (MH) susceptibility using the European MH Group (EMHG) protocol has been performed in some laboratories but only on a small sample from the combined EMHG. Thus, the purpose of the present study was to determine combined EMHG sensitivity and specificity of the test.Methods: Results of IVCT of patients with previous fulminant MH and normal, low-risk subjects (controls) were collected from 22 centresof the EMHG. IVCT was performed according to the EMHG protocol. Patients were included inthe study if the clinical crisis had a score of at least 50 points with the Clinical Grading Scale. Low-risk subjects were included provided they did not belong to a family with known MH susceptibility, they had not developed any signs of MH at previous anaesthetics, and they did not suffer from any neuromuscular disease. For inclusion of both MH patientsand low-risk subjects, at least 1 muscle bundle in the IVCT should have twitches of 10 mN(1 g) or more. For evaluation of individual tests, only muscle bundles with twitch heights of 10 mN (1 g) or more were used.Results: A total of 1502 probands had undergone IVCT because of a previous anaesthesia with symptoms and signs suggestive of MH. Of these, 119 had clinical scores of 50 and above. From these 119 MH-suspected patients and from 202 low-risk subjects, IVCT data were collected. Subsequently, 14 MH-suspected patients were excluded from further analysis for thefollowing reasons: In 3 patients, the suspected MH episode could be fully explained by diseases other than MH; in 11 MHS patients, IVCT was incomplete (n=l), data were lost (n=3), or none of the muscle bundles fulfilled twitch criteria (n=7). Of the remaining 105 MH-suspected patients, 89 were MHS, 10 MHEh, 5 MHEc, and one MHN. Thus, we observed a diagnostic sensitivity of the IVCT of 99.0% if the MHE group is considered susceptible(95% confidence interval 94.8–100.0%). Of the 202 low-risk subjects, 3 were MHS, 5 MHEh, 5 MHEc, and 189 MHN. This gives a specificity of the IVCT of 93.6% (95% confidence interval 89.2–96.5%).Conclusion: The IVCT for diagnosis of MH susceptibility in Europe has a high sensitivity and a satisfactory specificity.
Case reports have linked malignant hyperthermia (MH) to several genetic diseases. The objective of this study was to quantitatively assess excess comorbidities associated with MH diagnosis in pediatric hospital discharge records. Data for this study came from the Kids' Inpatient Database (KID) for the years 2000, 2003, and 2006. The KID contains an 80% random sample of patients under the age of 21 discharged from short-term, non-Federal hospitals in the United States, with up to 19 diagnoses recorded for each patient. Using all pediatric inpatients as the reference, we calculated the standardized morbidity ratios (SMRs) and 95% confidence intervals (CIs) for children with MH diagnosis according to major disease groups and specific medical conditions. Of the 5,916,989 nonbirth-related hospital discharges studied, 175 had a recorded diagnosis of MH. Compared with the general pediatric inpatient population, children with MH diagnosis were significantly more likely to be diagnosed with diseases of the musculoskeletal system and connective tissue (SMR 5.7; 95% CI: 3.9-7.9), diseases of the circulatory system (SMR 3.3; 95% CI: 2.1-4.8), and congenital anomalies (SMR 3.2; 95% CI: 2.3-4.4). The specific diagnosis that was most strongly associated with MH was muscular dystrophies (SMR 31.3; 95% CI 12.6-64.6). Diseases of the musculoskeletal system and connective tissue are significantly associated with MH diagnosis in children. Further research is warranted to determine the clinical utility of these comorbidities in assessing MH susceptibility in children.
Malignant hyperthermia (MH) is a pharmacogenetic syndrome that variably expresses itself on exposure to triggering agents. MH prevalence in the United States is not well documented. In this study, we assessed the prevalence of MH in New York State hospitals. Using New York hospital discharge data for the years 2001 through 2005, we identified all patients with a diagnosis of MH due to anesthesia using International Classification of Diseases, Ninth Revision, Clinical Modification code 995.86. MH prevalence was evaluated by demographic and clinical characteristics. Of the 12,749,125 discharges from New York hospitals during the study period, 73 patients had a recorded diagnosis of MH due to anesthesia. Nearly three quarters of the MH patients were male and 71% were patients from emergency/urgent admissions. The estimated prevalence rate of MH was 0.96 (95% confidence interval [CI] 0.67-1.24) per 100,000 surgical discharges and 1.08 (95% CI 0.75-1.41) per 100,000 discharges in which there was any indication of exposure to anesthesia. The estimated prevalence of MH for males was 2.5 to 4.5 times the rate for females. The prevalence of MH due to anesthesia in surgical patients treated in New York State hospitals is approximately 1 per 100,000. MH risk in males is significantly higher than in females.
Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disorder with an estimated mortality of less than 5%. The purpose of this study was to evaluate the current incidence of MH and the predictors associated with in-hospital mortality in the United States. The Nationwide Inpatient Sample, which is the largest all-payer inpatient database in the United States, was used to identify patients discharged with a diagnosis of MH during the years 2000-2005. The weighted exact Cochrane-Armitage test and multivariate logistic regression analyses were used to assess trends in the incidence and risk-adjusted mortality from MH, taking into account the complex survey design. From 2000 to 2005, the number of cases of MH increased from 372 to 521 per year. The occurrence of MH increased from 10.2 to 13.3 patients per million hospital discharges (P = 0.001). Mortality rates from MH ranged from 6.5% in 2005 to 16.9% in 2001 (P < 0.0001). The median age of patients with MH was 39 (interquartile range, 23-54 yr). Only 17.8% of the patients were children, who had lower mortality than adults (0.7% vs. 14.1%, P < 0.0001). Logistic regression analyses revealed that risk-adjusted in-hospital mortality was associated with increasing age, female sex, comorbidity burden, source of admission to hospital, and geographic region of the United States. The incidence of MH in the United States has increased in recent years. The in-hospital mortality from MH remains elevated and higher than previously reported. The results of this study should enable the identification of areas requiring increased focus in MH-related education.
Two recent studies by the Institute of Medicine on the reliability of hospital discharge data abstracted from patients' medical records raise serious questions about the adequacy of information on diagnoses and procedures. The findings are particularly timely, since increasingly important decisions about the content of medical care and levels of reimbursement may be based on such information. A series of recommendations are offered to guide the use and improvement of abstracted medical record information.
Reimbursement of hospitals by Medicare under the prospective-payment system is based on patients' diagnoses as coded at discharge. During the period October 1984 through March 1985, we studied the accuracy of the coding for diagnosis-related groups (DRGs) in hospitals receiving Medicare reimbursement. We used a two-stage cluster method to sample 7050 medical records from 239 hospitals that were stratified according to size. Using blinded techniques with reliability checks, medical-record specialists reabstracted the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes to assign correct DRGs to discharged patients. The correct DRGs were then compared with those originally assigned by the physician and the hospital administration. The study revealed an error rate of 20.8 percent in DRG coding. Errors were distributed equally between physicians and hospitals. Small hospitals had significantly higher error rates. Previous studies had found that errors occurred randomly, so that half the errors benefited the hospital financially and half penalized the hospital. The present study found that a statistically significant 61.7 percent of coding errors favored the hospital. These errors caused the average hospital's case-mix index--a measure of the complexity of illness of the hospital's patients--to increase by 1.9 percent. As a result, hospitals received higher net reimbursement from Medicare than was supportable by the medical records. We conclude that "creep" does occur in the coding of DRGs, resulting in overpayment to hospitals for patients covered by Medicare.