CLINICAL RESEARCH STUDY
Incidence of intracranial hemorrhage in patients with
atrial fibrillation who are prone to fall
Brian F. Gage, MD, MSc,aElena Birman–Deych, MS,aRoger Kerzner, MD,b
Martha J. Radford, MD,cDavid S. Nilasena, MD, MSPH, MS,dMichael W. Rich, MDb
aDivision of General Medical Sciences, Washington University School of Medicine, and
bDivision of Cardiology, Washington University School of Medicine, St. Louis, Missouri;
cCenter for Outcomes Research and Evaluation at Yale New Haven Health System, and Division of Cardiology, Yale
School of Medicine, New Haven, Connecticut; and the
dCenters for Medicare and Medicaid Services, Dallas, Texas.
PURPOSE: Patients at high risk for falls are presumed to be at increased risk for intracranial
hemorrhage, and high risk for falls is cited as a contraindication to antithrombotic therapy. Data
substantiating this concern are lacking.
METHODS: Quality improvement organizations identified 1245 Medicare beneficiaries who were
documented in the medical record to be at high risk of falls and 18 261 other patients with atrial
fibrillation. The patients were elderly (mean 80 years), and 48% were prescribed warfarin at hospital
discharge. The primary endpoint was subsequent hospitalization for an intracranial hemorrhage, based
on ICD-9 codes.
RESULTS: Rates (95% confidence interval [CI]) of intracranial hemorrhage per 100 patient-years
were 2.8 (1.9–4.1) in patients at high risk for falls and 1.1 (1.0–1.3) in other patients. Rates (95% CI)
of traumatic intracranial hemorrhage were 2.0 (1.3–3.1) in patients at high risk for falls and 0.34
(0.27–0.45) in other patients. Hazard ratios (95% CI) of other independent risk factors for intracranial
hemorrhage were 1.4 (1.0–3.1) for neuropsychiatric disease, 2.1 (1.6–2.7) for prior stroke, and 1.9
(1.4–2.4) for prior major bleeding. Warfarin prescription was associated with intracranial hemorrhage
mortality but not with intracranial hemorrhage occurrence. Ischemic stroke rates per 100 patient-years
were 13.7 in patients at high risk for falls and 6.9 in other patients. Warfarin prescription in patients
prone to fall who had atrial fibrillation and multiple additional stroke risk factors appeared to protect
against a composite endpoint of stroke, intracranial hemorrhage, myocardial infarction, and death.
CONCLUSION: Patients at high risk for falls with atrial fibrillation are at substantially increased risk
of intracranial hemorrhage, especially traumatic intracranial hemorrhage. However, because of their
high stroke rate, they appear to benefit from anticoagulant therapy if they have multiple stroke risk
© 2005 Elsevier Inc. All rights reserved.
0002-9343/$ -see front matter © 2005 Elsevier Inc. All rights reserved.
The American Journal of Medicine (2005) 118, 612–617
In atrial fibrillation trials of carefully selected partici-
pants, antithrombotic therapy prevented strokes with an
acceptable rate of intracranial hemorrhages: 0.3 intracranial
hemorrhage per 100 patient-years with aspirin and 0.4–0.5
intracranial hemorrhage per 100 patient-years with warfa-
rin.1-3However, elderly patients at high risk for falls were
excluded from clinical trials,2-10and no longitudinal data
quantify the risk of intracranial hemorrhage and stroke in
Perception of traumatic intracranial hemorrhage risk in-
fluences selection of antithrombotic therapy. Surveys11,12
and medical record review13demonstrate that physicians
avoid antithrombotic therapy in elderly patients with atrial
fibrillation who seem likely to fall and sustain an intracra-
nial hemorrhage. Epidemiological studies have found that
antithrombotic therapy can double the risk of intracranial
hemorrhage,14,15especially fatal events.16Thus, accurate
knowledge of the rate of intracranial hemorrhage in patients
at high risk for falls with atrial fibrillation would help
determine the optimal antithrombotic therapy.
Our primary goal was to quantify the incidence of intra-
cranial hemorrhage in Medicare beneficiaries with atrial
fibrillation who were at high risk of falls. Our secondary
goals were to identify independent risk factors for intracra-
nial hemorrhage and to quantify the benefits of warfarin
therapy, if any, in patients at high risk for falls.
The primary endpoint was hospitalization for an intra-
cranial hemorrhage after the index hospital admission. The
study was approved by the Washington University human
Formation of the second national registry of
The National Registry of Atrial Fibrillation II dataset
was created from 23 657 anonymous patient records gath-
ered by Quality Improvement Organizations for the Na-
tional Stroke Project. The project was managed by the Iowa
Foundation for Medical Care. The dataset included both
Medicare records and chart-abstracted data from 3586 hos-
pitals in all 50 US states. Medical records were selected as
a random sample stratified by state from all Medicare ben-
eficiaries who were hospitalized with an International Clas-
sification of Diseases, 9th Revision, Clinical Modification
(ICD-9) code for atrial fibrillation (427.31) in any diagnos-
tic position and who were discharged between April 1, 1998
and March 31, 1999. We obtained inpatient (part A) and
outpatient (part B) Medicare records from 1995 through
The structured abstraction of data from medical charts
was performed by the Clinical Data Abstraction Centers,
which confirmed the presence of atrial fibrillation during the
index admission. The remaining records were systemati-
cally reviewed for risk of falls, stroke risk factors, and
discharge medications. Chart abstractors were unaware of
the study’s endpoints.
Intracranial hemorrhage and ischemic strokes in the fol-
low-up period were identified by recently validated ICD-9
codes in Medicare Part A data. We identified ischemic
stroke from ICD-9 codes 433.x1, 434.x1, 436, 437.1, and
437.9 (“x” represents any digit) in any position. As com-
pared to structured chart abstraction, these codes have a
positive predictive value of 96%.17We identified nontrau-
matic intracranial hemorrhages from codes 430x–432x and
traumatic intracranial hemorrhage from codes 800.2x,
800.3x, 800.7x, 800.8x, 801.2x, 801.3x, 801.7x, 801.8x,
803.2x, 803.3x, 803.7x, 803.7x, 804.2x, 804.3x, 804.7x,
804.8x, 852, and 853. The positive predictive value of these
ICD-9 codes for intracranial hemorrhage is 77%.17
In a subgroup analysis we identified myocardial infarc-
tion from ICD-9 code 410.x and noncerebral hemorrhage
based on ICD-9 codes validated by White et al.14We
assessed predictive validity of the high-fall-risk designation
using Medicare Part A and B claims by assessing for falls
(E880.0-E886.9, E888) and fractures (800-829).
In the primary analysis we censored patients at the time
of their last hospitalization if they died outside of the hos-
pital because neither Medicare Part A or B claims nor the
Medicare Denominator File provides cause of death. Like-
wise, those who died after the baseline hospitalization (be-
fore another hospitalization) were excluded (n ? 1824). In
a secondary analysis, we included out-of-hospital deaths as
part of a composite endpoint that also included stroke,
intracranial hemorrhage, and myocardial infarction. For
beneficiaries who experienced multiple adverse events, we
excluded events and days of follow-up that occurred after
the initial event.
The only acceptable source of information for risk of
falls was physician documentation in the medical record.
The terms “frequent falls,” “history of falls,” “multiple
falls,” or “tendency for falls” were considered synonymous
Grant Support: Supported by the American Heart Association
(0270099N). Disclaimer: The conclusions presented are solely those of the
authors and do not represent those of the Quality Improvement Organiza-
tions, American Heart Association, or CMS. The content of this publication
does not necessarily reflect the views or policies of the Department of
Health and Human Services, nor does mention of commercial products
imply endorsement of them by the U. S. Government. The authors assume
full responsibility for the accuracy and completeness of the ideas presented.
Requests for reprints should be sent to: Brian F. Gage, MD, MSc,
Division of General Medical Sciences, Washington University School of
Medicine Campus Box 8005, 660 S. Euclid Ave., St. Louis, MO 63110.
E-mail address: firstname.lastname@example.org.
613 Gage et al Risk of Intracranial Hemorrhage in Patients Prone to Fall
with high risk for falls; a single fall was insufficient docu-
mentation for this designation. We also identified a trial-like
cohort comprising patients who lacked the following co-
morbid conditions: high risk for falls, age 80 or older,
chronic renal disease, uncontrolled hypertension, malig-
nancy, alcoholism, history of bleeding, neuropsychiatric
impairment, prior ischemic stroke or transient ischemic at-
tack (TIA), anemia, bleeding disorder, and combination
therapy with warfarin and aspirin at discharge.
We used time-to-event analyses to test our hypotheses
that the risks of intracranial hemorrhage and of stroke were
greater in patients at high risk for falls. We used backward
elimination to develop parsimonious Cox models. We ver-
ified the proportionality assumption graphically and by
time-dependent covariates. In the intracranial hemorrhage
model, we tested for effects of history of ischemic stroke or
TIA, age, sex, race, alcoholism, history of bleeding, a bleed-
ing disorder (eg, hemophilia or leukemia), nursing home
residence, neuropsychiatric impairment (schizophrenia, de-
mentia, or Parkinson’s disease), and antithrombotic therapy.
In the ischemic stroke Cox model, we tested for effects of
sex, nursing home residence, antithrombotic therapy, and
stroke factors. We quantified the risk of stroke using a
clinical prediction (CHADS2) that assigns 1 point for the
presence of Congestive heart failure, Hypertension, Age ?
75, or Diabetes mellitus, and 2 points for a prior Stroke or
TIA.18,19In a subgroup analysis, we initially stratified the
analysis into CHADS2scores of 0–1, 2, or 3–6, because the
benefit of warfarin therapy is greater in patients with atrial
fibrillation at greater risk of stroke.20Because the apparent
benefit of warfarin was similar in patients with 2 points and
with 3–6 points, we combined these two cohorts.
Statistical tests were two-tailed. We performed statistical
analyses in SAS version 9.0 (SAS Institute Inc; Cary, NC).
Subjects at high risk for falls were older and had more
comorbidities than other patients. In addition, they were
significantly less likely to receive warfarin or aspirin ther-
apy (Table 1).
Trial-like patients (n ? 3236) were younger (mean age,
73 years) and healthier (mean number of bleeding risk
factors, 0.6). Most of them were prescribed antithrombotic
therapy (53.7% warfarin; 23.1% aspirin).
Data integrity and validation
We validated the fall-risk designation by examining
ICD-9 codes for falling and for nonpathologic fractures that
were coded after the baseline hospitalization. Compared to
other patients, patients at high risk for falls were 2.0 (95%
CI: 1.6–2.4) times more likely to fall. The rates of fractures
per 100 patient-years were 27.9 in patients at high risk for
falls and 12.0 in other patients.
The rates (Table 2) of intracranial hemorrhage per 100
patient-years were 2.8 (95% CI: 1.9–4.1) in patients at high
risk for falls and 1.1 (95% CI: 1.0–1.3) in other patients (P
? 0.0001, log-rank test). In the subset of the trial-like
patients, the rate of intracranial hemorrhage was 0.53 (95%
CI: 0.3–0.8). The rates of traumatic intracranial hemorrhage
per 100 patient-years were 2.0 (95% CI: 1.3–3.1) in patients
at high risk for falls and 0.34 (95% CI: 0.27–0.45) in other
patients (P ? 0.0001, log-rank test).
In the multivariate Cox model (Table 3), patients at high
risk for falls were 1.9 (95% CI 1.3–2.9) times more likely to
have any intracranial hemorrhage and 4.1 (95% CI 2.4–7.1)
times more likely to have a traumatic intracranial hemor-
rhage than other patients. Prior stroke (HR 2.2), prior major
bleeding (HR 1.8), and neuropsychiatric impairment (HR
Demographic and clinical factors of study cohorts
n ? 1245
n ? 18 261
Age, mean (SD)*
Race and ethnicity
Asian or other race
Warfarin at discharge*
Discharged to nursing
Bleeding risk factors
Chronic renal disease
Rebleeding risk (ie,
Increased age (? 75)*
TIA is transient ischemic attack.
*P ? 0.05.
614The American Journal of Medicine, Vol 118, No 6, June 2005
1.4) also were independently associated with any intracra-
nial hemorrhage (Table 3). Prescription of warfarin or as-
pirin at baseline did not significantly affect risk of intracra-
nial hemorrhage: the HR for warfarin was 1.0 (95% CI
0.8–1.4) and the HR for aspirin was 1.1 (95% CI 0.8–1.4).
Alcohol abuse, non-Caucasian race, bleeding disorder, and
renal disease were too infrequent in the dataset to quantify
After an intracranial hemorrhage, 30-day mortality was
42% in patients at high risk of falls and 48.2% in other
patients (P ? 0.2). The intracranial hemorrhage 30-day
mortality was 51.8% in patients who had been prescribed
warfarin, and 33.6% in patients who had not been pre-
scribed warfarin after the baseline hospitalization (P ?
0.007). In a stepwise logistic regression model, the only
independent predictors of 30-day mortality post intracranial
hemorrhage were prior prescription of warfarin (odds ratio
2.5; 95% CI 1.4–4.5, P ? 0.002) and nursing home resi-
dency (odds ratio 3.3; 95% CI 1.6–6.8, P ? 0.0009).
Stroke rates (95% CI) per 100 patient-years were 13.7
(11.6–16.3) in patients at high risk for falls and 6.9 (6.5–
7.3) in other patients. In the subset of the trial-like patients,
the stroke rate was 2.8 (95% CI: 2.3–3.4). Compared to
other patients, patients at high risk for falls had a 1.3-fold
(95% CI: 1.1–1.6) increased risk of stroke (P ? 0.002).
Each 1-point increase in the CHADS2score increased the
risk of stroke by a factor of 1.42 (95% CI: 1.37–1.47, P ?
0.0001). Hazard ratios (HR) and 95% CI of other indepen-
dent stroke risk factors were neuropsychiatric impairment
1.22 (1.06–1.40, P ? 0.05) and nursing home residence
1.45 (1.29–1.64, P ?0.0001); warfarin prescription at hos-
pital discharge had a modestly protective effect 0.78 (0.70–
0.86, P ?0.0001). After stroke, 30-day mortality was 34.4%
among high-fall-risk subjects, 27.8% in other patients, and
21.8 % in the trial-like cohort.
Risks and benefits of warfarin therapy in patients
at high risk for falls
To determine the potential benefit of prescribing warfa-
rin in patients at high risk for falls, we quantified the
association between warfarin use and the composite out-
come of hospitalization for stroke, any hemorrhage (includ-
ing intracranial hemorrhage), myocardial infarction, or out-
of-hospital death (except in patients with terminal disease).
In the Cox model that controlled for bleeding risk factors,
aspirin prescription, nursing home residency, and sex, war-
farin was significantly protective in 1086 patients with 2 or
more CHADS2points (HR 0.75), but not protective in 159
patients with 0 or 1 points in (HR 0.98) (Table 4). The
P-value for interaction between warfarin and stroke risk was
not significant (P ? 0.31).
Despite their low use of warfarin (33.5%), patients at
high risk for falls suffered 2.8 intracranial hemorrhages per
100 patient-years, more than twice the 1.1 intracranial hem-
orrhage rate of other participants and more than 5 times the
0.5 rate of trial-like participants. The increased risk of
intracranial hemorrhage in patients at high risk for falls was
due to their increased incidence of traumatic intracranial
hemorrhage, which was increased four-fold compared to
other patients, even after adjusting for the covariates. The
30-day mortality after an intracranial hemorrhage was sig-
Rates of intracranial hemorrhage, stratified by
Intracranial hemorrhage rate (95% CI) per 100 patient-years
(n ? 1245)
(n ? 18 261)
*P ? 0.0001 High-fall vs other patients.
†P ? 0.0005 High-fall vs other patients.
(HR) of independent predictors of intracranial hemorrhage
Multivariate Cox regression showing hazard ratios
FactorHR (95% CI)
High-risk for falls
out-of-hospital death or hospitalization for stroke,
myocardial infarction, or hemorrhage—in 1245 patients at
high risk for falls
Hazard ratio of warfarin for composite outcome—
Aspirin or nil
CHADS2stroke score was calculated by adding 1 point for each of
the following conditions: congestive heart failure, hypertension, age
? 75 years, or diabetes and 2 points for a prior stroke or transient
ischemic attack. CI indicates confidence interval.
615 Gage et alRisk of Intracranial Hemorrhage in Patients Prone to Fall
nificantly greater in patients who had been prescribed war-
farin after the baseline hospitalization (51.8%) than in pa-
tients who had not been prescribed warfarin (33.6%). These
observations highlight the substantial risk and mortality of
intracranial hemorrhage in populations who are older and
frailer than carefully selected trial participants.
Despite the significant association between intracranial
hemorrhage and fall risk, the findings support the use of
anticoagulants in patients at high risk for falls who are at
moderate to high risk of stroke. Prescribing warfarin in
patients at high risk for falls with 2 or more CHADS2points
was associated was a 25% relative risk reduction (HR 0.75)
in the composite outcome (Table 4). When prescribing
warfarin to these patients, providers could instruct them to
take precautions to limit their risk of falling: wear stable
shoes,21exercise regularly,22take vitamin D,23use walking
aids,24and discontinue unnecessary medications.24-26
In contrast to the potential benefits of warfarin in patients
with greater CHADS2scores, prescribing warfarin in pa-
tients at high risk for falls with 0 or 1 CHADS2points was
associated with a nonsignificant reduction in the composite
outcome (Table 4). Because the 95% confidence interval of
the HR (0.98) was wide (0.59–1.72), warfarin could either
be beneficial or harmful in this population. Given this un-
certainty and the known expense, hassle, and risks of war-
farin therapy, we recommend aspirin or no antithrombotic
therapy for this population.
Besides fall risk, prior stroke, prior bleeding, and neuro-
psychiatric impairment were associated with incident intra-
cranial hemorrhage. Others also have found an association
between prior stroke and intracranial hemorrhage.27,28The
mechanism behind this association may be loss of micro-
vascular integrity or disruption of neurovascular homeosta-
sis. Patients with a history of epistaxis are more likely to
have an intracranial hemorrhage,29and patients with a prior
intracranial hemorrhage, especially a primary lobar intra-
cranial hemorrhage, are at increased risk of recurrence.30
The association between intracranial hemorrhage and neu-
ropsychiatric disease may depend on the type of neuropsy-
chiatric disease and the degree of impairment in perfor-
mance status.31Psychiatric disease may cause falls because
of treatment with psychotropic medications,25,26associated
alcohol use, or poor compliance. Patients with Parkinson’s
disease can fall because of a festinating gait.32Patients with
Alzheimer’s dementia may be predisposed to intracranial
hemorrhage if they have cerebral amyloid angiopathy or
certain apolipoprotein E polymorphisms.33-35
This study has limitations inherent to use of administra-
tive data. First, because all participants were deidentified,
we were not able to validate the diagnosis of intracranial
hemorrhage by reviewing brain-imaging studies. However,
the ICD-9 codes we used to identify intracranial hemor-
rhage have a specificity of over 99%.17Had we corrected
for the known misclassification rate of ICD-9 codes for
intracranial hemorrhage, incidence rates would be increased
by a factor of 1.26. A second limitation is that we knew
what antithrombotic therapy was prescribed at hospital dis-
charge but did not capture subsequent initiation or discon-
tinuation of therapy. Thus, the observed lack of association
between warfarin and intracranial hemorrhage in this study
does not refute such an association.36,37A third limitation is
that we had to exclude patients who died after the baseline
hospitalization and without another hospitalization because
they had no follow-up data. A minor limitation was that we
could not evaluate risk factors for intracranial hemorrhage
that were unavailable (eg, leukoaraiosis on brain imaging or
tobacco use). Likewise, we used physician documentation
to ascertain risk of falls and were unable to evaluate the risk
of specific impairments in strength, balance, vision, or or-
These limitations are offset by several strengths. First,
the cohort design allowed us to calculate incidence rates and
to avoid recall bias. Second, we were able to use structured
medical record abstraction to adjust for potential confound-
ing factors. Third, the large size and national sample of the
dataset provide great generalizability. Fourth, the designa-
tion “high-fall-risk” predicted subsequent fractures and
falls, validating the designation. The specificity between the
relationship between high-fall-risk and traumatic intracra-
nial hemorrhage validates the association.
In summary, patients at high risk for falls are at substan-
tially increased risk of intracranial hemorrhage, especially
traumatic intracranial hemorrhage. However, because of
their increased risk of stroke, they appear to benefit from
anticoagulant therapy if they have atrial fibrillation and at
least 2 CHADS2points.
The authors appreciate the assistance of the Iowa Foun-
dation for Medical Care, the other Quality Improvement
Organizations, and the Centers for Medicare & Medicaid
Services (CMS) in providing data that made this research
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617Gage et alRisk of Intracranial Hemorrhage in Patients Prone to Fall