National estimates of adverse events during nonpsychiatric hospitalizations for persons with schizophrenia.
ABSTRACT Persons with schizophrenia comprise a vulnerable population that may be disproportionately susceptible to medical injuries. The objective of this study was to determine the association between diagnosis of schizophrenia and adverse events during non-psychiatric hospitalizations.
We studied U.S. hospital discharges from 2002-2007 using the Nationwide Inpatient Sample. We determined the nationally weighted association of schizophrenia with the Agency for Healthcare Research and Quality's Patient Safety Indicators after adjusting for patient, hospitalization, and hospital characteristics.
There were 269,387 non-psychiatric hospitalizations with schizophrenia, and 37,092,651 without. Hospitalizations with schizophrenia had elevated adjusted odds ratios for PSIs compared with those without schizophrenia for decubitus ulcer (1.43, 95% CI: 1.36-1.51); infection from medical care (1.19, 95% CI: 1.08-1.30); postoperative respiratory failure (1.96, 95% CI: 1.67-2.30); sepsis (1.59, 95% CI: 1.25-2.02); and pulmonary embolism/deep venous thrombosis (1.23, 95% CI: 1.13-1.35). Adjusted odds ratios for iatrogenic pneumothorax (1.12, 95% CI: 0.94-1.33) and postoperative hemorrhage (1.07, 95% CI: 0.88-1.31) were not significantly different in persons with schizophrenia, while the adjusted OR for accidental puncture (OR=0.66, 95% CI: 0.58-0.74) was reduced in persons with schizophrenia.
Persons with schizophrenia are more likely to experience the most common types of medical injuries. Improved understanding of factors related to hospital quality of care and outcomes in this group will be important to plan interventions to enhance patient safety for persons with schizophrenia.
- SourceAvailable from: Sigrun Hope[Show abstract] [Hide abstract]
ABSTRACT: Background: Schizophrenia and bipolar disorder are debilitating disorders. In addition to classic psychotic and mood symptoms, frequency of cognitive disturbances and mortality from cardiovascular disease are high. Inflammation has been associated with both cognitive disturbances and cardiovascular disease. Recent studies have indicated increased inflammation in patients with severe mental disorders. However, these studies are small and have a limited number of inflammatory markers. This makes it difficult to draw any conclusions about the mechanisms involved. No studies have investigated if inflammatory disturbances differ between schizophrenia and bipolar disorder. Inflammation has been associated with depression and mania, but it is still unclear how it relates to mood symptoms and affective states. Aims: The aims were to determine if patients with severe mental disorder have high levels of inflammation, if they have a specific inflammatory profile, if inflammatory disturbances differ between schizophrenia and bipolar disorder patients, and if inflammatory profile is associated with mood symptoms or affective state. Methods: 312 patients from a catchment area were included together with 239 healthy controls. Patients were diagnosed according to DSM-V, and degree of depression and mania was assessed with standard instruments. Four general inflammatory markers were measured: Tumor necrosis factor receptor 1 (TNF-R1), Interleukin 1 receptor antagonist (IL-1Ra), Interleukin 6 (IL-6) and high-sensitivity CRP (hs- CRP). Three specific markers were measured: The platelet related inflammatory marker CD40L ligand (sCD40L), the endothelial related marker von Willebrand factor (vWf) and the calcium related inflammatory marker Osteoprotegerin (OPG). Routine biochemical blood tests and clinical characteristics, which could confound associations, were also assessed. Results: Patients had a similar immune profile with highly significant increase of TNF-R1, vWf and OPG (p<0.000002, p<0.000002, and p=0.01 respectively). The results were significant also after control for confounding factors. Contrary to expectations, depressed bipolar disorder patients had the lowest levels of inflammation and manic patients had the highest. Degree of depressive mood was also inversely correlated with inflammation, which was significant for OPG (p=0.0003), IL-1Ra (p=0.001) and IL-6 (p= 0.002). Patients in manic state had significantly higher levels of OPG, vWf, IL-1Ra and sTNF-R1. There were no associations between mood and inflammation in schizophrenia. Discussion: The study indicated that the general inflammatory marker TN-R1, as well as endothelial and calcium related inflammation may play a role in severe mental illness pathology. TNF-R1 has been found to be involved in neuronal plasticity, and related to cognitive dysfunction, which is an important clinical characteristic of the disorders. The results are also in line with recent findings that endothelial dysfunction and calcium metabolism are involved in the pathology. Furthermore, OPG and vWf are risk factors of cardiovascular disease and the high levels in patients may be related to their elevated mortality rates. It has been fairly well documented that inflammation induces typical sickness behavior, with reduced energy, increased sleep and depressive mood. Therefore, it was unexpected that inflammation was increased in the manic state. This suggests that there may be other inflammatory mechanisms involved. Conclusions: Both bipolar disorder and schizophrenia show increased TNF-R1, OPG and vWf. This immune profile suggests inflammatory disturbances related to neuroplasticity, endothelial function and calcium regulation. In bipolar disorder patients, elevated mood is characterized by high levels of inflammation, while depressed mood is characterized by low. This suggests that inflammatory disturbances may be involved with core psychopathology of bipolar disorder. The study supports that inflammatory disturbances are of importance in severe mental disorders.04/2012, Degree: PhD, Supervisor: Ole A Andressen
- General Hospital Psychiatry 11/2010; 32(6):644-644. · 2.90 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Several risk factors of venous thromboembolism (VTE) and pulmonary embolism (PE) were found in patients with schizophrenia. Therefore, we hypothesize that the incidences of VTE and PE are relatively higher among schizophrenia patients in comparison with the general population. For this population-based cohort study, claims data from 1996 to 2011 were obtained from the National Health Insurance Research Database in Taiwan. We compared the incidence of DVT and PE between schizophrenia and non-schizophrenia cohorts. Cox proportional hazard regression models were used to analyze the risk of DVT and PE, according to sex, age, and comorbidities. Compared with the non-schizophrenia cohort, the schizophrenia cohort exhibited a 2.02-fold higher adjusted hazard ratio (HR) for developing DVT, and a 1.99-fold higher adjusted HR for developing PE. Furthermore, schizophrenia patients using first-generation or second-generation antipsychotics exhibited a higher adjusted HR for both DVT and PE development. Compared with the general population, the risk of DVT and PE is relatively higher among schizophrenia patients. Early diagnosis and intervention by physicians could mitigate complications and reduce mortality resulting from VTE. Copyright © 2015 Elsevier B.V. All rights reserved.Schizophrenia Research 01/2015; · 4.43 Impact Factor
National estimates of adverse events during nonpsychiatric
hospitalizations for persons with schizophrenia☆,☆☆
Elizabeth Khaykin, Ph.D., M.H.S., S.M.a,⁎, Daniel E. Ford, M.D., M.P.H.b,
Peter J. Pronovost, M.D., Ph.D.c,d,e,f,g, Lisa Dixon, M.D., M.P.H.h,
Gail L. Daumit, M.D., M.H.S.i
aDepartment of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
bDepartment of Medicine, Johns Hopkins University School of Medicine, and Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
cDepartment of Anesthesiology and Critical Care Medicine, The Johns Hopkins University, Baltimore, MD, USA
dDepartment of Surgery, The Johns Hopkins University, Baltimore, MD, USA
eDepartment of Health Policy and Management, The Johns Hopkins University, Baltimore, MD, USA
fDivision of Adult Critical Care, The Johns Hopkins University, Baltimore, MD, USA
gCenter for Innovation in Quality Patient Care, Johns Hopkins Medicine, Baltimore, MD, USA
hMental Illness Research, Education and Clinical Center (MIRECC), VA Capitol Health Care Network, and the University of Maryland School of Medicine,
Baltimore, MD, USA
iJohns Hopkins Medical Institutions, Welch Center for Prevention, Epidemiology and Clinical Research, Baltimore, MD, USA
Received 5 February 2010; accepted 21 April 2010
Objective: Persons with schizophrenia comprise a vulnerable population that may be disproportionately susceptible to medical injuries. The
objective of this study was to determine the association between diagnosis of schizophrenia and adverse events during non-psychiatric
Methods: We studied U.S. hospital discharges from 2002-2007 using the Nationwide Inpatient Sample. We determined the nationally
weighted association of schizophrenia with the Agency for Healthcare Research and Quality's Patient Safety Indicators after adjusting for
patient, hospitalization, and hospital characteristics.
Results: There were 269,387 non-psychiatric hospitalizations with schizophrenia, and 37,092,651 without. Hospitalizations with
schizophrenia had elevated adjusted odds ratios for PSIs compared with those without schizophrenia for decubitus ulcer (1.43, 95% CI: 1.36-
1.51); infection from medical care (1.19, 95% CI: 1.08-1.30); postoperative respiratory failure (1.96, 95% CI: 1.67-2.30); sepsis (1.59, 95%
CI: 1.25-2.02); and pulmonary embolism/deep venous thrombosis (1.23, 95% CI: 1.13-1.35). Adjusted odds ratios for iatrogenic
pneumothorax (1.12, 95% CI: 0.94-1.33) and postoperative hemorrhage (1.07, 95% CI: 0.88-1.31) were not significantly different in persons
with schizophrenia, while the adjusted OR for accidental puncture (OR=0.66, 95% CI: 0.58-0.74) was reduced in persons with schizophrenia.
Conclusions: Persons with schizophrenia are more likely to experience the most common types of medical injuries. Improved understanding
of factors related to hospital quality of care and outcomes in this group will be important to plan interventions to enhance patient safety for
persons with schizophrenia.
© 2010 Elsevier Inc. All rights reserved.
Keywords: Schizophrenia; Vulnerable populations; Patient safety; Medical errors; Administrative data
Available online at www.sciencedirect.com
General Hospital Psychiatry xx (2010) xxx–xxx
☆☆A version of “National Estimates of Adverse Events in Persons With Schizophrenia” was presented on April 8, 2009, in B14B Hampton House, Johns
Hopkins School of Public Health as part of a Department of Mental Health seminar. The data presented was not updated for the latest available year of the
Nationwide Inpatient Sample.
⁎Corresponding author. Welch Center for Prevention, Epidemiology and Clinical Research, Baltimore, MD 21287, USA. Tel.: +1 410 502 8893; fax: +1
410 955 0476.
E-mail address: email@example.com (E. Khaykin).
0163-8343/$ – see front matter © 2010 Elsevier Inc. All rights reserved.
ARTICLE IN PRESS
The publication of The Institute of Medicine Report on
medical errors a decade ago sparked a national dialogue
regarding patient safety by highlighting the effects of
medical mistakes on mortality and morbidity, and the
resulting economic costs . Since then, focus on patient
safety has grown. In 2006, the President signed the Deficit
Reduction Act requiring the Secretary of Health and
Human Services to identify conditions that could reason-
ably have been prevented through the application of
evidence-based guidelines. As of October 1, 2008,
Medicare no longer pays hospitals for the care they
provide to treat some preventable injuries such as
decubitus ulcers, pulmonary emboli and objects left in a
patient during surgery .
While patient safety issues are receiving increased
attention, national estimates of adverse event rates for
certain vulnerable populations are still missing. Persons
with schizophrenia comprise an at-risk population with a
mortality rate three times higher than the general
population and a large burden of medical comorbid
conditions . This group may be disproportionately
susceptible to medical injuries due to the need for multiple
medications, communication difficulties, cognitive impair-
ment and a relative lack of social support . Hospitaliza-
tions for medical or surgical problems may be especially
risky for persons with schizophrenia if mental health
status hampers the ability to perceive and communicate
medical symptoms . Health care provider and system
factors such as perceiving physical complaints as
psychosomatic and potential for errors with psychotropic
medications may also be responsible for adverse events in
persons with schizophrenia hospitalized for nonpsychiatric
The Patient Safety Indicators (PSIs) developed by the
Agency for Healthcare Research and Quality (AHRQ)
identify possible adverse events occurring during hospi-
talization by using readily available hospital inpatient
data. Because hospital administrative data are collected
routinely for billing purposes and are population
based, they provide an efficient source of information
on medical injuries.
The purpose of this study was to determine the
association between diagnosis of schizophrenia and
adverse events during nonpsychiatric hospitalizations.
This study used data from the Nationwide Inpatient
Sample (NIS) to determine whether the cumulative
incidence of PSIs differed by schizophrenia status in
nonpsychiatric hospitalizations after adjusting for patient,
hospitalization and hospital characteristics. We hypothe-
sized that adverse events would be more frequent in
hospitalizations for persons with schizophrenia than for the
general population, especially those indicators that may be
related to medication resulting in oversedation and
2.1. Study population and data sources
We conducted a study of United States hospital
discharges from 2002 to 2007 for adults 18 years and older
with and without a secondary diagnosis of schizophrenia
(ICDM-9 code 295). Eligible discharges included hospitali-
zations without a primary psychiatric diagnosis.
Six years of nonconfidential, deidentified data were
obtained from the NIS, one in a family of databases in the
Healthcare Cost and Utilization Project, a federal-state-
industry partnership sponsored by AHRQ . The NIS is the
largest all-payer inpatient care database in the United States
with each year containing approximately 8 million hospital
stays from about 1000 hospitals in 35 states. One year of the
NIS approximates a 20% stratified sample of US community
hospitals. The NIS contains data on age, sex, length of stay,
hospital charges and ICD-9-CM codes for up to 15 diagnoses
and 15 procedures. The NIS also contains information on
hospital characteristics such as urban/rural location, teaching
status, control of hospital (public vs. private) and discharge
volume from the American Hospital Association's Annual
We created variables for analyses from the NIS. First, we
used AHRQ software to create a set of discharge-level
indicators of adverse events or PSIs. We then used AHRQ's
Clinical Classifications Software  to consider the
following medical conditions from the Charlson Index as
measures of comorbidity: congestive heart failure, chronic
obstructive pulmonary disease (COPD), liver disease, kidney
disease, diabetes, cancer, HIV/AIDS in addition to alcohol or
drug abuse, and other conditions known to be elevated in
persons with schizophrenia .
To protect patient confidentiality, the NIS does not have
identifiers to link hospitalizations to unique individuals. The
Johns Hopkins (Baltimore, MD) Institutional Review Board
deemed that this study, using secondary data, met criteria
2.2. Patient safety indicators
The PSIs comprised our primary outcomes to identify
adverse events occurring during hospitalization. These
include complications of surgery, medical negligence and
iatrogenic conditions; each indicator has inclusion and
exclusion criteria to identify appropriate risk pools and
minimize uncertainty as to whether an event was preventable
. We used discharge-based PSIs to determine the
proportions of events with a denominator of a relevant
group of discharges. For example, for pulmonary embolism
or deep vein thrombosis (PE/DVT), the numerator is “cases
of deep vein thrombosis or pulmonary embolism” and the
denominator is “surgical discharges.”
The development process for the PSIs included a detailed
evidence-based review of candidate indicators and their
reliability and validity followed by clinical and coding expert
2 E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS
review, revision of the candidate indicators and empirical
testing with hospital administrative data for the indicators
rated as valuable by the expert review. The PSIs are thought
to have reasonable validity and specificity when used as
screening tools for examining incidence and risk factors
associated with medical adverse events [11,12]. However,
because the data are collected for billing purposes, the PSIs
are not meant to be used as authoritative measures of patient
safety, but to recognize areas where quality of care may need
more in-depth investigation.
To avoid unreliable statistical measures from indicators
with very low numbers of events, we decided a priori to
select a threshold of 70 events per cell to include a PSI in the
analysis . From all 16 discharge-level nonobstetric PSIs
for years 2002 to 2007, the following had an adequate
number of events to be included: decubitus ulcers; infection
due to medical care; accidental puncture or laceration;
iatrogenic pneumothorax; postoperative respiratory failure;
postoperative sepsis; postoperative PE/DVT; and postoper-
ative hemorrhage or hematoma.
2.3. Statistical analysis
We determined the nationally weighted proportions of
patient, hospitalization and hospital characteristics in
hospitalizations for patients with and without a secondary
Characteristics of US hospitalizations from 2002 to 2007 for patients with
and without secondary diagnosis of schizophreniaa,b
Mean age, years
Median age, years
Primary payer, %
Median household income
(national quartile for
patient zip code), %c
Quartile 1 (lowest)
Quartile 4 (highest)
Region of country
for hospital, %
Urban hospital location
Hospital bed sized
Hospital volume, %e
Quartile 1 (lowest)
Quartile 4 (highest)
Death in hospital
Admission source, %
Another facility including
Comorbid illness, %
Congestive heart failure
(continued on next page)
Table 1 (continued)
Any substance abuse
Median length of stay,
days (interquartile range)
Median total charge,
US$ (interquartile range)
13,538 (7319–26,868) 14,675 (7954–28,972)
aResults are nationally weighted and account for stratified sampling.
bAll characteristics are significantly different except renal failure.
cFor median income of patient zip code: Quartile 1 means the patients'
zip code is in the 0–25th percentile of all zip codes, Quartile 2 is in the
26–50th percentile, Quartile 3 is in the 51st to 75th percentile and Quartile 4
is in the 76–100th percentile.
dCutoff points for bed size were made so that approximately one-third
of the hospitals in a given region, location and teaching status combination
would fall within each bed size category.
eFor hospital volume quartile: Quartile 1 means the hospital has
between 0 and 9109 annual discharges, Quartile 2 has 9110 to 17,171
discharges, Quartile 3 has 17,172 to 26,442 and Quartile 4 has over 26,442
fNonelective admissions include emergency, urgent, newborn, delivery
3E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS
diagnosis of schizophrenia. Differences in characteristics
between hospitalizations with and without schizophrenia
were tested using the Wilcoxon rank sum for continuous
variables and chi-squared tests for categorical variables.
We also determined the nationally weighted cumulative
incidences of PSIs in hospitalizations for patients with and
without a secondary diagnosis of schizophrenia.
To test the hypothesis that hospitalizations for patients
with a secondary diagnosis of schizophrenia are more
likely to have certain adverse events, we developed logistic
regression models to obtain odds ratios (ORs) for each PSI
taking into account the NIS sampling design and sample
discharge weights. In these weighted, logistic regression
models, we adjusted for the patient characteristics of age,
sex, payer (commercial insurance, Medicaid, Medicare,
self-pay); median income for zip code (quartiles); emer-
gency room admission and indicators of medical comorbid
conditions: disease of the circulatory system (congestive
heart failure, valvular disease, pulmonary circulation
disorders, peripheral vascular disorder and hypertension);
COPD; liver disease; diabetes/obesity; HIV/AIDS; and
substance abuse (drugs or alcohol). Nonpostoperative
adverse events were also adjusted for medical vs. surgical
diagnosis upon admission. Race was missing for approx-
imately 30% of observations, and known race did not
change effect sizes so it was not included in the models. In
the full models, we also adjusted for the hospital
characteristics of urban/rural location, teaching status,
hospital control (public, private, public and private
collapsed category) and hospital discharge volume quartile.
No interaction by year was found in regression models so
we pooled years 2002 to 2007.
Tests were two sided and P values were considered
significant at the .05 alpha level. Since the unit of
observation was hospitalization and not person, multiple
hospitalizations per patient were likely. Survey design-
based variance estimators used in the analyses take into
account this within-respondent correlation. All analyses
used SAS 9.2 (SAS Institute, Inc.) or SAS-Callable
SUDAAN 9.2 (Research Triangle Institute).
3.1. Characteristics of hospital stays for patients with and
Between 2002 and 2007, the NIS contained 3605
hospitals, 269,387 nonpsychiatric hospitalizations for adult
patients with a secondary diagnosis of schizophrenia and
37,092,651 hospitalizations for those without a secondary
diagnosis of schizophrenia (Table 1). Weighted comparisons
between admissions for patients with and without schizo-
phrenia showed that those with schizophrenia were more
likely to be nonwhite, male, have a medical admission (vs.
surgical) and were over twice as likely to have a nonelective
admission (vs. elective). Almost 87% of admissions for
Cumulative incidence of adverse events per 1000 US hospitalizations from
2002 to 2007 for patients with and without a secondary diagnosis of
Patient safety indicatorsIncidence with
Infection due to medical care
Accidental puncture or laceration
Pulmonary embolism or deep
Hemorrhage or hematoma
3.2 (2.6–3.8) 2.7 (2.6–2.8)
aResults are nationally weighted and account for stratified sampling.
Odds ratios of adverse events in US hospitalizations from 2002 to 2007 for patients with and without a secondary diagnosis of schizophreniaa
Patient safety indicators Unadjusted OR
adjusted OR (95% CI)b
Patient and hospital
adjusted OR (95% CI)c
Infection due to medical care
Accidental puncture or laceration
Pulmonary embolism or deep venous thrombosis
Hemorrhage or hematoma
0.45 (0.40– 0.49)
aResults are nationally weighted and account for stratified sampling.
bAdjusted for age, sex, primary payer, median income (national quartile for patient zip code), admission from emergency room, disease of the
circulatory system, COPD, liver, diabetes/obesity, HIV, substance abuse, surgical vs. medical admission. Postoperative adverse events not adjusted for medical
vs. surgical admission.
cAdjusted for urban vs. rural hospital location, hospital teaching status, hospital control and hospital volume quartile in addition to patient
4 E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS
patients with a secondary diagnosis of schizophrenia had
either Medicaid or Medicare as payers compared with about
58% in those without schizophrenia. Persons with schizo-
phrenia were more likely to live in a zip code with the lowest
quartile of median income. Reflecting the established burden
of comorbid medical conditions in persons with schizophre-
nia, admissions for patients with a secondary diagnosis of
schizophrenia had a substantially higher percentage of
congestive heart failure, COPD, liver disease, diabetes,
HIV/AIDS and substance abuse compared with those
without schizophrenia. In addition, discharges for persons
with schizophrenia were more likely to include an in-hospital
death and had higher median charges and length of stay than
discharges without schizophrenia.
3.2. Adverse events for patients with and without
schizophrenia during hospitalization
In both hospitalizations with and without schizophrenia,
the highest cumulative incidences of PSIs were for decubitus
ulcer, respiratory failure, pulmonary embolism/deep venous
thrombosis and sepsis (Table 2). After adjusting for patient
and hospital characteristics, the ORs of the following PSIs
were significantly higher for hospitalizations with a second-
ary diagnosis of schizophrenia compared to those without a
secondary diagnosis of schizophrenia: decubitus ulcer (1.43,
CI: 1.08–1.30), postoperative respiratory failure (1.96, 95%
CI: 1.67–2.30), sepsis (1.59, 95% CI: 1.25–2.02) and
pulmonary embolism/deep venous thrombosis (1.23, 95%
CI: 1.13–1.35) (Table 3). The PSIs of iatrogenic pneumo-
thorax (1.12, 95% CI: 0.94–1.33) and postoperative
of schizophrenia. Adjusted odds of accidental puncture were
significantly reduced in hospitalizations with a secondary
diagnosis of schizophrenia (OR=0.66, 95% CI: 0.58–0.74).
In the United States from 2002 through 2007, we found
that hospitalizations for persons with a secondary diagnosis
of schizophrenia had increased odds of decubitus ulcer,
infection due to medical care, postoperative respiratory
failure, sepsis and pulmonary embolism/deep venous throm-
bosis when compared to the general population. Accidental
secondary diagnosis of schizophrenia. Adjusting for hospital
characteristics had little influence on these ORs.
Little is known about optimal perioperative management
of medications in patients with schizophrenia. However,
overdosing, underdosing and interactions between analge-
sics, anesthetics and patients' regular psychotropic medica-
tions may lead to postoperative delirium, confusion or
oversedation which could cause aspiration and other
respiratory complications following surgery [14,15]. The
odds of postoperative respiratory failure were almost twice
as high in hospitalizations for persons with schizophrenia
compared to those without schizophrenia, the most elevated
for all of the measured PSIs.
Postoperative delirium and other behavioral issues not
uncommonly result in sedation and restraints for patients
with schizophrenia . By reducing mobility, sedation or
the use of restraints may increase the risk of decubitus
ulcers, venous thromboembolism, nosocomial infection and
postoperative respiratory failure in persons with schizo-
phrenia. In addition, behavioral aspects of the psychiatric
disorder , reduced pain sensitivity  and effects of
sedation may reduce the recognition of these complications
We also found that the adjusted odds of accidental
puncture or laceration were significantly decreased when
comparing hospitalizations with a secondary diagnosis of
schizophrenia to those without. This may be explained by the
potentiallylower rate ofriskysurgical proceduresforpersons
with schizophrenia. The denominator for this complication
includes all types of surgical discharges so that it does not
control for the seriousness of the procedure or the number of
procedures during hospitalization. A previous study found
that individuals with mental illnesses were substantially less
likely to obtain revascularization procedures following a
myocardial infarction than persons without SMI .
A previous study determined the ORs of various adverse
events associated with a secondary diagnosis of schizophre-
nia in Maryland hospitals for 2001 to 2002 . Infections
due to medical care, postoperative respiratory failure, sepsis
and venous thromboembolism all had increased odds in
hospitalizations with schizophrenia; however, the magnitude
was higher for nosocomial infections and thromboembolism
compared to the results of this study. Unlike the current
study, the Maryland study did not find increased odds for
decubitus ulcers. These differences may be due to geograph-
ic differences, a smaller sample, differences in the variables
available in the Maryland hospital data or the earlier version
of the PSI software available at that time.
The relationship between schizophrenia and PSIs may be
subject to geographical variations because of differences in
the way persons with schizophrenia receive care in different
parts of the country. For example, a study conducted by
Betemps et al.  found that hospital geographic location
was significantly associated with differences in use of
seclusion and restraint, citing different standards of practice
or laws between states. In addition, the authors found the
group most often secluded or restrained was persons with
schizophrenia. Sample size limitations did not permit us to
examine the interaction between schizophrenia diagnosis
and state on the occurrence of adverse events.
4.1. Methodological strengths and limitations
The AHRQ PSIs provide a screen for a variety of
potential adverse events during hospitalizations. Many
5 E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS
previous investigations of medical injuries rely on medical
record abstraction. These studies can provide information
on clinical variables during hospitalization and a better
understanding of the preventability of a patient safety
event. However, creating standard and accepted definitions
for preventability in patient safety is challenging. Chart
abstraction studies require medical expertise to perform and
are costly . As a result, most of these studies are limited
to a relatively small sample of patients and cannot provide
a cost-effective way of screening for adverse events for
special populations, nor could they address the scope of the
problem on a national scale. This analysis uses data
stratified and weighted to the general US population of
patients attending community hospitals that are already
collected for management and billing purposes. The large
size of the dataset makes it suitable to study small
subgroups such as persons with schizophrenia that may
be more vulnerable to adverse events.
Residual confounding is a common limitation to using
large administrative databases. For example, since persons
with schizophrenia tend to be poorer and have only public
insurance, they may be more likely to be admitted to lower
quality hospitals. Although adjusting for hospital character-
istics thought to be associated with hospital quality did not
result in large changes to the ORs, we cannot rule out the
role hospital quality plays in the elevated rates of some of
Residual confounding from undetected or unreported
medical disease in hospitalizations for patients with
schizophrenia could also explain part of the associations
we found between schizophrenia and the PSIs. Persons
with schizophrenia also have a higher rate of lifestyle risk
factors (e.g., obesity and smoking) which may not be fully
captured by the variables available in the data . These
lifestyle factors may increase a patient's susceptibility to
experiencing an adverse event. For example, the extremely
high rates of smoking in people with SMI are likely to play
a role in respiratory function, infection and hypercoagula-
bility, making persons with schizophrenia at greater risk of
adverse events from respiratory failure, nosocomial infec-
tion and deep vein thrombosis, respectively.
Accuracy of clinical coding on hospital discharge
summary and medical billing records affects every variable
in our analysis, from the main exposure of schizophrenia to
patients' comorbidities, demographic characteristics and the
PSIs. Previous studies have found that administrative
database tools have had low sensitivity, but high specificity,
for adverse events; thus injuries are often underreported .
However, we do not believe coding should be systematically
different for hospitalizations for persons with schizophrenia
compared to the general population.
The AHRQ PSIs are not definitive measures of adverse
events, yet they emphasize areas of concern for quality of
care that warrant further study. This analysis suggests that
persons with schizophrenia may be more vulnerable to some
types of medical injuries that can occur during hospitaliza-
tion, and these differences often persist after controlling for
known patient, hospitalization and hospital characteristics.
Higher rates of adverse events for hospitalizations in
persons with schizophrenia raise questions about effective
communication among health care providers and between
health care providers and this vulnerable patient population.
Improved understanding of factors related to hospital
quality of care and outcomes in this group will be important
to plan interventions to enhance patient safety for persons
 Kohn LT, Corrigan JM, Donaldson MS. (Institute of Medicine). To Err
Is Human: Building a Safer Health System. Washington (DC):
National Academy Press; 2000.
 Rosenthal MB. Nonpayment for performance? Medicare's new
reimbursement rule. N Engl J Med 2007;357:1573–5.
 Colton CW, Manderscheid RW. Congruencies in increased mortality
rates, years of potential life lost, and causes of death among public
mental health clients in eight states. Prev Chronic Dis 2006;3:A42.
 Brown S, Inskip H, Barraclough B. Causes of the excess mortality of
schizophrenia. Br J Psychiatry 2000;177:212–7.
 Cooke BK, Magas LT, Virgo KS, Feinberg B, Adityanjee A, et al.
Appendectomy for appendicitis in patients with schizophrenia. Am J
 Goldman LS. Medical illness in patients with schizophrenia. J Clin
 HCUP Nationwide Inpatient Sample (NIS). Healthcare Cost and
Utilization Project (HCUP), 2002-2007. Agency for Healthcare
Research and Quality, Rockville, MD. Available at: http://www.
 HCUP Clinical Classifications Software (CCS) for ICD-9-CM.
Healthcare Cost and Utilization Project (HCUP), 2004. Agency for
Healthcare Research and Quality, Rockville, MD. Available at: http://
 Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of
classifying prognostic comorbidity in longitudinal studies: develop-
ment and validation. J Chron Dis 1987;40:373–83.
 Agency for Healthcare Research and Quality. Indicators—Guide to
Patient Safety Indicators. Rockville (MD): Agency for Healthcare
Research and Quality; 2003. AHRQ Publication 03-R203.
 Zhan C, Miller MR. Administrative data based patient safety
research: a critical review. Qual Saf Health Care 2003;12(Suppl 2):
 Romano PS, Geppert JJ, Davies S, Miller MR, Elixhauser A, et al. A
national profile of patient safety in US hospitals. Health Aff
 Coffey R, Barrett M, Houchens B, et al. Methods Applying AHRQ
Quality Indicators to Healthcare Cost and Utilization Project
(HCUP) Data for the National Healthcare Quality Report, 2003.
HCUP Methods Series Report #2003-05 ONLINE. March 19, 2005.
U.S. Agency for Healthcare Research and Quality. Available at:
 Ely EW, Shintani A, Truman B, Speroff T, Gordon SM, Harrell Jr FE,
et al. Delirium as a predictor of mortality in mechanically ventilated
patients in the intensive care unit. JAMA 2004;291:1753–62.
 Copeland LA, Zeber JE, Pugh MJ, Mortensen EM, Restrepo MI, et al.
Postoperative complications in the seriously mentally ill: a systematic
review of the literature. Ann Surg 2008;248:31–8.
6 E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS
 Karlström G, Olerud S. The management of tibial fractures in
alcoholics and mentally disturbed patients. J Bone Joint Surg Br
 Bonnot O, Anderson GM, Cohen D, Willer JC, Tordjman S. Are
patients with schizophrenia insensitive to pain? A reconsideration of
the question. Clin J Pain 2009;25:244–52.
 Druss BG, Bradford DW, RosenheckRA, Radford MJ, Krumholz HM.
Mental disorders and use of cardiovascular procedures after myocar-
dial infarction. JAMA 2000;238:506–11.
 Daumit GL, Pronovost PJ, Anthony CB, Guallar E, Steinwachs
DM, et al. Adverse events during medical and surgical hospitaliza-
tions for persons with schizophrenia. Arch Gen Psychiatry 2006;63:
 Betemps EJ, Somoza E, Buncher CR. Hospital characteristics,
diagnoses, and staff reasons associated with use of seclusion and
restraint. Hosp Community Psychiatry 1993;44:367–71.
 Rosen AK, Geraci JM, Ash AS, McNiff KJ, Moskowitz MA.
Postoperative adverse events of common surgical procedures in the
Medicare population. Med Care 1992;30:753–65.
 Romano PS, Chan BK, Schembri ME, Rainwater JA. Can adminis-
trative data be used to compare postoperative complication rates across
hospitals? Med Care 2002;40:856–67.
7 E. Khaykin et al. / General Hospital Psychiatry xx (2010) xxx–xxx
ARTICLE IN PRESS