ORIGINAL RESEARCH

Annals of Internal Medicine

Firearm-Related Hospitalization and Risk for Subsequent Violent
Injury, Death, or Crime Perpetration
A Cohort Study
Ali Rowhani-Rahbar, MD, MPH, PhD; Douglas Zatzick, MD; Jin Wang, PhD; Brianna M. Mills, MA; Joseph A. Simonetti, MD, MPH;
Mary D. Fan, MPhil, JD; and Frederick P. Rivara, MD, MPH

Background: Risk for violent victimization or crime perpetration
after firearm-related hospitalization (FRH) must be determined to
inform the need for future interventions.
Objective: To compare the risk for subsequent violent injury,
death, or crime perpetration among patients with an FRH, those
hospitalized for noninjury reasons, and the general population.
Design: Retrospective cohort study.
Setting: All hospitals in Washington.
Patients: Patients with an FRH and a random sample of those
with a non–injury-related hospitalization in 2006 to 2007 (index
hospitalization).
Measurements: Primary outcomes included subsequent FRH,
firearm-related death, and the combined outcome of firearm- or
violence-related arrest ascertained through 2011.
Results: Among patients with an index FRH (n = 613), rates of
subsequent FRH, firearm-related death, and firearm- or violencerelated arrest were 329 (95% CI, 142 to 649), 100 (CI, 21 to 293),
and 4221 (CI, 3352 to 5246) per 100 000 person-years, respectively. Compared with the general population, standardized incidence ratios among patients with an index FRH were 30.1 (CI,
14.9 to 61.0) for a subsequent FRH and 7.3 (CI, 2.4 to 22.9) for

S

eventy percent of homicides and 10% of nonfatal
violent crimes in the United States are related to
firearms (1–3). There are 40 times as many nonfatal
firearm-related crimes as there are firearm-related
deaths, and 23% of victims of such crimes sustain an
injury (3). Of those with nonfatal firearm-related injuries
who receive medical attention in the emergency department, an estimated 30% to 60% are hospitalized,
depending on the injury intent (4). Overall, firearmrelated hospitalizations (FRHs) are associated with substantial physical and psychological morbidity as well as
societal cost (5–7).
Information on the risk for subsequent violent victimization (that is, becoming a victim) or crime perpetration after an FRH is lacking. Such information must
be obtained to inform the need for future interventions

See also:
Related article . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513
Celebrating the ACP Centennial: From the Annals
Archive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
Editorial comment . . . . . . . . . . . . . . . . . . . . . . . . . 520

firearm-related death. In survival analyses that accounted for
competing risks, patients with an index FRH were at greater risk
for subsequent FRH (subhazard ratio [sHR], 21.2 [CI, 7.0 to 64.0]),
firearm-related death (sHR, 4.3 [CI, 1.3 to 14.1]), and firearm- or
violence-related arrest (sHR, 2.7 [CI, 2.0 to 3.5]) than those with a
non–injury-related index hospitalization.
Limitation: Lack of information on whether patients continued
to reside in Washington during follow-up may have introduced
outcome misclassification.
Conclusion: Hospitalization for a firearm-related injury is associated with a heightened risk for subsequent violent victimization
or crime perpetration. Further research at the intersection of clinical care, the criminal justice system, and public health to evaluate the effectiveness of interventions delivered to survivors of
firearm-related injury is warranted.
Primary Funding Source: Seattle City Council and University of
Washington Royalty Research Fund.

Ann Intern Med. 2015;162:492-500. doi:10.7326/M14-2362 www.annals.org
For author affiliations, see end of text.
This article was published online first at www.annals.org on 24 February
2015.

among this group of patients. For example, interventions, such as brief motivational interviewing, conducted among trauma patients during their hospitalization have been shown to reduce rates of posttraumatic
stress and alcohol use disorders as well as trauma and
violent behavior recidivism while improving functional
recovery (8 –10). An enhanced understanding of the
subsequent risk for violent injury, death, or crime perpetration may help frontline health care providers, public health professionals, criminal justice officials, and
policymakers devise and implement integrated risk assessment plans and harm reduction strategies at the
time of hospitalization and after discharge among patients with an FRH.
We conducted a statewide epidemiologic investigation to determine the absolute rates of subsequent
violent injury, death, or crime perpetration after discharge among patients with an FRH, and to compare these rates with those of 2 comparison groups
comprising patients hospitalized for noninjury reasons
and the general population. Our hypothesis was
that patients with an FRH were at highest risk for
violent injury, death, or crime perpetration after
discharge.

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 ORIGINAL RESEARCH

Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

METHODS

EDITORS' NOTES

Overview of Study Design
We used a retrospective cohort study design. First,
using codes from the International Classification of Diseases, Ninth Revision (ICD-9), we identified all trauma
patients hospitalized in 2006 to 2007 in Washington.
Each patient's first hospitalization during these years
was defined as their index hospitalization. We chose 2
comparison groups: a random sample of patients with
a non–injury-related index hospitalization frequency
matched with the injury group on age and year of hospitalization, and the general population of Washington.
Information on outcomes was collected through 31 December 2011. The Human Subject Division of the
Washington State Department of Health approved the
study protocol and procedures.
Exposures
Consistent with prior literature, an injury-related
hospitalization was defined as a hospital discharge with
a primary diagnosis of an acute injury (ICD-9 codes 800
to 959). Using codes for external causes of injury (E
codes), we excluded records for the following mechanisms: injuries from medical and surgical misadventures (E870 to E879), late effects of injury (E929 or
E999), and adverse effects of substances in therapeutic
use (E930 to E949) (11).
Information on index hospitalization was obtained
by using the Washington State Comprehensive Hospital Abstract Reporting System (CHARS) (12), which contains coded hospital inpatient discharge information
and is used to collect an array of data elements, such as
age, sex, payer status, and codes for diagnoses and
procedures. Using ICD-9 and E codes, we categorized
index hospitalizations into the following distinct subgroups: violent injury, which was further divided into
firearm-related (of any intent [assault, self-inflicted, unintentional, or undetermined]) and non–firearm-related
(assault or self-inflicted) injuries; nonviolent injury; and
noninjury. We used the definition of a violent death
from the National Violent Death Reporting System

Context
Understanding the risks faced by patients after a
firearm-related hospitalization (FRH) may help efforts
to prevent further injury and improve outcomes.
Contribution
This statewide-study found that after a FRH, patients
were at markedly elevated risks for recurrent FRH,
firearm-related death, and firearm- or violence-related
arrest.
Implication
Identification of variables associated with the risk for
subsequent adverse outcomes may help guide interventions at the time of FRH.

(NVDRS) (“an injury resulting either from the intentional
use of physical force or power against oneself, another
person, or a group or community” [13]) as a guide to
define violent injury in this investigation. Consistent
with NVDRS practice, we included firearm injuries of
any intent in the subgroup of violent injury.
The primary exposure was index FRH. Secondary
exposures included index hospitalization related to
nonfirearm violence and hospitalization for a nonviolent injury. Index noninjury hospitalization served as the
reference category.
Outcomes
Outcomes measured after index hospitalization discharge were subsequent violence-related hospitalization, death, or arrest. Statewide records on all hospitalizations, deaths, and arrests from 2006 through 2011
were obtained from CHARS, the Washington State Department of Health, and the Washington State Patrol,
respectively.

Figure 1. Pictorial representation of study design.
Before Index
Hospitalization

Index
Hospitalization

After Index
Hospitalization

Hospitalizations

Arrests

Convictions

Deaths

2001

2006

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2007

2011

Annals of Internal Medicine • Vol. 162 No. 7 • 7 April 2015 493

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Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

Subsequent injury-related hospitalizations and
deaths were classified with the same categorization
scheme used for index hospitalization. We used specific codes in the Revised Code of Washington to classify arrests as due to a firearm-related or violent crime
or a nonfirearm nonviolent crime. Because the Revised
Code of Washington does not typically distinguish between violent crimes that involve firearms and those
that do not, we grouped firearm-related crimes (such as
theft) and violent crimes (regardless of whether a firearm was involved) into 1 class (“firearm- or violencerelated arrest”), as recommended by previous investigators who faced this methodological limitation (14).
We used the definition of a violent crime used by the
Uniform Crime Reporting program of the Federal Bureau of Investigation (“an offense that involves force or
threat of force, including criminal homicide, forcible
rape, robbery, and aggravated assault” [15]) as a guide
to define a violent crime.
Primary outcomes included subsequent FRH,
firearm-related death, and the combined outcome of
firearm- or violence-related arrest. Secondary outcomes included subsequent hospitalization for a nonfirearm violent injury, nonfirearm violent death, and arrest for a nonfirearm nonviolent crime.
Covariates
Information on age, sex, payer status, year and season of discharge, and county of the hospital for index
hospitalization was captured. We also sought to examine the association of history of a diagnosis of psychiatric disorder, arrest, and conviction with the aforementioned outcomes. For this purpose, statewide records
on all hospitalizations, arrests, and convictions from
2001 through 2005 were obtained from CHARS, the
Washington State Patrol, and the Administrative Office
of the Courts Judicial Information System, respectively.
Figure 1 provides a pictorial representation of the overall study design.
Statistical Analysis
Probabilistic algorithms were used to link each patient's index hospitalization record to their hospitalization, vital status, arrest, and conviction records. A subset of identifiers, including first 2 letters of the first
name, first 2 letters of the last name, date of birth, sex,
and first 3 digits of ZIP code of residence, was used for
the linkage. The analytic database was restricted to
matches with an accuracy likelihood of at least 99%
(Appendix, available at www.annals.org).
Follow-up began on the day of index hospitalization discharge and ended on the day of the subsequent
event (first hospitalization, death, or first arrest, each in
its corresponding analysis) or on 31 December 2011,
whichever occurred first. For the analysis of subsequent
hospitalization, follow-up began 90 days after index
hospitalization discharge to minimize potential misclassification of readmissions for index injury as new recurrent injury events. In a sensitivity analysis, we used a
180-day period after index hospitalization discharge.
We conducted an additional sensitivity analysis in
which the follow-up time for subsequent arrest began 1

day after index hospitalization discharge to minimize
potential misclassification of arrests for index injury as
new criminal events. We calculated the incidence rate
of each outcome by type of index hospitalization. The
cumulative incidence of a subsequent event for each
type of index hospitalization was estimated by using
the unadjusted cumulative incidence function, with
death treated as a competing event for hospitalization
and arrest, and other-cause mortality treated as a competing event for firearm-related mortality.
In regression analyses, we used the methods described by Fine and Gray (16) to model each outcome
with the subdistribution hazards regression, with death
treated as a competing event for hospitalization and
arrest, and other-cause mortality treated as a competing event for firearm-related mortality. Subhazard ratios
(sHRs) and their corresponding CIs were determined
by using models that included variables for age, sex,
payer status, county of the hospital, discharge year and
season, history and type of arrest, and history and type
of psychiatric disorder diagnosis. In a sensitivity analysis, history of crime was represented as a combination
of arrest and conviction records (convicted, arrested
but not convicted, or not arrested).
Using the age and sex distribution of the 2000 U.S.
Census population, we calculated standardized incidence and mortality ratios to compare the risk for a
subsequent FRH and death between patients with an
index FRH and persons in the general population of
Washington. An ! level of 0.05 was used to denote
statistical significance. All tests were 2-sided and were
done by using SAS, version 10 (SAS Institute), and Stata
13 (StataCorp), with the stcrreg and stcurve package
for Fine and Gray (16) modeling and the dstdize package for standardization.
Role of the Funding Source
The study was funded by the Seattle City Council
and the University of Washington Royalty Research
Fund. The funding sources had no role in the design,
conduct, or reporting of this study or the decision to
submit the manuscript for publication.

RESULTS
There were 77 138 index injury-related hospitalizations in 2006 to 2007. Of these, 9048 (11.7%) were due
to a violent injury, including hospitalizations related to
firearms (n = 680), nonfirearm assaults (n = 2526), and
nonfirearm self-inflicted injuries (n = 5842). We also
studied 180 841 patients with an index hospitalization
that was not injury-related. Compared with patients admitted for other reasons, a greater proportion of patients with an index FRH and nonfirearm assault-related
hospitalization were male and had at least 1 prior
firearm- or violence-related arrest or conviction. A
greater proportion of patients with a violent injury at
index hospitalization had at least 1 arrest or conviction
for a nonfirearm nonviolent crime and a hospitalization
in which a diagnosis of psychiatric disorder was noted
on any of the discharge abstract fields before their index hospitalization (Table 1).

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 Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

ORIGINAL RESEARCH

Table 1. Characteristics of the Study Population, by Type of Index Hospitalization*
Characteristic

Violent Injury (n ! 9048)
Firearm
(Any Intent)
(n ! 680)

Hospital deaths

Nonfirearm
Assault
(n ! 2526)

Nonviolent
Injury
(n ! 68 090)

Noninjury
(n ! 180 841)

Self-Inflicted
(n ! 5842)

67 (9.9)

65 (2.6)

145 (2.5)

5626 (8.3)

4147 (2.3)

Age
≤19 y
20–39 y
40–59 y
≥60 y

130 (19.1)
374 (55.0)
129 (19.0)
47 (6.9)

414 (16.4)
1196 (47.4)
796 (31.5)
120 (4.7)

838 (14.3)
2574 (44.1)
2075 (35.5)
355 (6.1)

7180 (10.5)
10 997 (16.2)
15 778 (23.2)
34 135 (50.1)

13 493 (7.4)
27 999 (15.5)
45 895 (25.4)
93 454 (51.7)

Male†

584 (85.9)

1991 (78.8)

2293 (39.3)

33 787 (49.6)

71 998 (39.8)

Payer status
Public
Private
Self

288 (42.4)
241 (35.4)
151 (22.1)

1266 (50.1)
739 (29.3)
521 (20.6)

2811 (48.1)
2240 (38.3)
791 (13.5)

38 378 (56.4)
25 003 (36.7)
4709 (6.9)

10 2611 (56.7)
72 502 (40.1)
5728 (3.2)

Discharge season‡
Winter
Spring
Summer
Fall

155 (22.8)
185 (27.2)
163 (24.0)
177 (26.0)

566 (22.5)
657 (26.1)
713 (28.3)
582 (23.1)

1516 (26.4)
1448 (25.3)
1443 (25.2)
1327 (23.1)

16 346 (24.0)
16 974 (25.0)
18 246 (26.8)
16 488 (24.2)

49 751 (27.8)
45 177 (25.2)
42 529 (23.7)
41 731 (23.3)

County of hospital§
King
Pierce
Snohomish
Other

222 (32.7)
138 (20.3)
56 (8.2)
264 (38.8)

873 (34.5)
406 (16.1)
171 (6.8)
1076 (42.6)

1280 (21.9)
833 (14.3)
526 (9.0)
3203 (54.8)

17 814 (26.1)
7840 (11.5)
6172 (9.1)
36 264 (53.3)

47 816 (26.5)
21 294 (11.8)
17 069 (9.4)
94 662 (52.3)

147 (21.6)
533 (78.4)

548 (21.7)
1978 (78.3)

576 (9.9)
5266 (90.1)

2209 (3.2)
65 881 (96.8)

2173 (1.2)
178 668 (98.8)

252 (37.1)
428 (62.9)

1100 (43.5)
1426 (56.5)

1240 (21.2)
4602 (78.8)

6268 (9.2)
61 822 (90.8)

6201 (3.4)
174 640 (96.6)

25 (3.7)
655 (96.3)

136 (5.4)
2390 (94.6)

142 (2.4)
5700 (97.6)

531 (0.8)
67 559 (99.2)

363 (0.2)
180 478 (99.8)

60 (8.8)
620 (91.2)

261 (12.6)
2207 (87.4)

390 (6.7)
5452 (93.3)

1731 (2.5)
66 359 (97.5)

1414 (0.8)
179 427 (99.2)

255 (37.5)
45 (6.6)
380 (55.9)

1348 (53.4)
140 (5.5)
1038 (41.1)

3289 (56.3)
1810 (31.0)
743 (12.7)

15 883 (23.3)
12 145 (17.8)
40 062 (58.8)

27 732 (15.3)
25 983 (14.4)
127 126 (70.3)

History of arrest
Firearm-related or violent crime
Yes
No
Nonfirearm nonviolent crime
Yes
No
History of conviction
Firearm-related or violent crime
Yes
No
Nonfirearm nonviolent crime
Yes
No
History of psychiatric disorder diagnosis
Substance use disorder
Other psychiatric disorder
None

* Data are numbers (percentages).
† Information was missing for 2 patients.
‡ Information was missing for 1805 patients.
§ Results are presented for the 3 largest counties in Washington and are collapsed for others for confidentiality reasons.

In terms of the intent of the injuries sustained by
patients with an FRH, 347 (51.0%) were assaults, 89
(13.1%) were self-inflicted, 192 (28.2%) were unintentional, and 52 (7.7%) were undetermined. Of 680 patients with an index FRH, 67 (9.9%) died during their
hospital stay. After index hospitalization discharge, patients with an index FRH had the highest rate of subsequent FRH (329 per 100 000 person-years [95% CI, 142
to 649]) and firearm- or violence-related arrest (4221
per 100 000 person-years [CI, 3352 to 5246]) among all

groups (Table 2). The rate of firearm-related death
among patients with an index FRH was 100 per 100 000
person-years (CI, 21 to 293). The cumulative incidence
of primary outcomes during follow-up by type of index
hospitalization is shown in Figure 2, and that of other
outcomes is shown in Appendix Figures 1 to 3 (available at www.annals.org).
In adjusted analyses, patients with an index FRH
were at significantly greater risk for a subsequent FRH
(sHR, 21.2 [CI, 7.0 to 64.0]), firearm-related death (sHR,

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Annals of Internal Medicine • Vol. 162 No. 7 • 7 April 2015 495

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Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

Table 2. Absolute Rates of Violence-Related Hospitalization, Arrest, or Death After Discharge, by Type of Index Hospitalization
Index Hospitalization

Hospitalization
Firearm
(Any Intent)

Nonfirearm
Assault

Violent injury (n = 8771)
Firearm (n = 613)
Nonfirearm, assault (n = 2461)
Nonfirearm, self-inflicted (n = 5697)
Nonviolent injury (n = 62 464)
Noninjury (n = 176 694)

Self-Inflicted

Hospitalizations,
n

Rate (95% CI)
per 100 000
Person-Years

Hospitalizations,
n

Rate (95% CI)
per 100 000
Person-Years

Hospitalizations,
n

Rate (95% CI)
per 100 000
Person-Years

8
4
1
16
13

329 (142–649)
41 (11–105)
5 (0.1–28.0)
8 (5–13)
2 (1–4)

12
46
12
100
57

494 (255–863)
470 (344–627)
60 (31–104)
50 (41–61)
10 (8–13)

3
18
307
195
207

123 (25–361)
184 (109–291)
1529 (1363–1710)
98 (84–112)
37 (32–42)

* 1-sided 97.5% CI.

4.3 [CI, 1.3 to 14.1]), and firearm- or violence-related
arrest (sHR, 2.7 [CI, 2.0 to 3.5]) than those hospitalized
for noninjury reasons (Table 3). In addition, patients
with an index FRH were at significantly greater risk for
nonfirearm assault-related hospitalization (sHR, 7.3 [CI,
3.5 to 14.9]) and nonfirearm nonviolent arrest (sHR, 1.9
[CI, 1.6 to 2.3]) than those hospitalized for noninjury
reasons. Controlling for a composite of history of arrests and convictions did not materially change the results (Appendix Table 1, available at www.annals.org).
Likewise, the 2 sensitivity analyses that included modified time at risk for ascertainment of subsequent hospitalization and arrest did not materially change the results. Patients with a history of arrest for a firearmrelated or violent crime were at especially high risk for a
subsequent firearm- or violence-related arrest and nonfirearm assault-related death, and those with a prior diagnosis of psychiatric disorder were at especially high
risk for subsequent nonfirearm self-inflicted injury and
death (Appendix Table 2, available at www.annals.org).
Patients with an index FRH were significantly more
likely than the general population of Washington to be
subsequently hospitalized (standardized incidence ratio, 30.1 [CI, 14.9 to 61.0]) or to die (standardized mortality ratio, 7.3 [CI, 2.4 to 22.9]) as a result of a firearmrelated injury.

DISCUSSION
To our knowledge, this study is one of the first
comprehensive investigations of violent victimization or
crime perpetration among patients with an FRH. We
found that these patients were at heightened risk for
subsequent firearm-related violent victimization or
crime perpetration. In addition, among hospitalized patients, prior criminality had a stronger association with
subsequent firearm- or violence-related arrest than did
a prior diagnosis of mental illness. These findings contribute meaningfully to the existing body of literature
on outcomes after an FRH and provide opportunities
for further research and collaboration on developing
clinical, criminal justice, and public health interventions
to reduce the burden of firearm-related morbidity, mortality, and criminality.

Assault is, by a large margin, the leading cause of
FRH in the United States, with almost no change in the
rate of assault-related FRH in the past decade (17, 18).
Consistent with prior findings, we found that 51% of all
index FRHs were due to assault (18). The vast majority
of patients with an FRH in this study were young men, a
demographic group known to be at heightened risk for
both victimization and criminal offending (19). Men represent the majority of both victims and perpetrators of
firearm-related homicides (2), and about 4 to 6 times as
many males as females commit suicide with a firearm in
the United States (1). In our study, we observed strong
associations between an index FRH and subsequent violent victimization or crime perpetration in adjusted
analyses, suggesting that the heightened risk is not
merely due to shared sociodemographic risk factors.
Nonfatal firearm-related injuries are associated
with a high burden of morbidity and health care utilization, but their adverse consequences do not end at discharge (20, 21). Survivors of gunshot wounds have substantial short- and long-term disabilities and declines in
a wide array of physical (such as functional status) and
psychological (such as posttraumatic stress disorder or
depression) outcomes after discharge that may in turn
lead to subsequent morbidity (for example, selfinflicted injury) and mortality (5, 7, 22, 23). Trauma recurrence has been the subject of several investigations
among heterogeneous populations of injured patients
(11, 24 –27); nonetheless, detailed information on risks
for subsequent injury-related hospitalization, death,
and criminal justice system involvement among persons who survive a firearm-related injury is needed. We
found that patients with an index FRH were not only
substantially more likely to experience a subsequent
firearm-related event, they were also more likely to be
subsequently hospitalized for a nonfirearm assaultrelated injury or arrested for a nonfirearm nonviolent
crime than those whose index hospitalization was not
injury-related.
A contribution of this study is to highlight the characteristics of a subset of persons who come into contact
with the health care system and are most likely to return
with violent injuries, die from those injuries, or be ar-

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Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

Table 2—Continued
Arrest
Firearm-Related or
Violent Crime

Death
Nonfirearm
Nonviolent Crime

Firearm
(Any Intent)

Nonfirearm
Assault

Self-Inflicted

Arrests,
n

Rate (95% CI)
per 100 000
Person-Years

Arrests,
n

Rate (95% CI)
per 100 000
Person-Years

Deaths,
n

Rate (95% CI)
per 100 000
Person-Years

Deaths,
n

Rate (95% CI)
per 100 000
Person-Years

Deaths,
n

Rate (95% CI)
per 100 000
Person-Years

81
224
457
1207
1496

4221 (3352–5246)
2918 (2548–3326)
2120 (1930–2324)
505 (477–535)
201 (191–211)

217
979
1286
5718
5377

11 307 (9853–12 917)
12 753 (11 966–13 577)
5966 (5644–6301)
2394 (2332–2457)
721 (702–741)

3
2
17
60
94

100 (21–293)
17 (2–60)
62 (36–100)
23 (18–30)
12 (10–15)

0
3
3
9
7

0 (0–123)*
25 (5–73)
11 (2–32)
3.4 (1.6–6.5)
1 (0.4–2.0)

2
2
69
41
95

67 (8–242)
17 (2–60)
252 (196–319)
16 (11–21)
12 (10–15)

rested for perpetrating violent crimes. Specifically, patients with prior criminality had a high likelihood of
being murdered within 5 years after their index hospitalization. The natural history of criminal careers, potential for recidivism, and risk factors for criminal offending
and victimization are well-described in the criminology
literature (28 –34). In particular, many prior investigations conducted outside the inpatient setting have documented the link between prior criminality and risk for
subsequent crime among persons who own or use
guns. For example, Wintemute and colleagues (14)
found that male handgun purchasers with prior convictions for a violent misdemeanor were more than 10
times as likely as those with no such history to be subsequently charged with a firearm-related or violent
crime. In our investigation, prior criminality had a stronger association with subsequent firearm- or violencerelated arrest than did a prior diagnosis of mental
illness. Findings of previous investigations have suggested that certain psychiatric illnesses, particularly
substance use disorders, are associated with an increased risk for trauma and violent behavior (24, 35,
36). Nonetheless, the relationship between mental illness and violent behavior is complex; the vast majority
of persons with mental illness do not engage in violent
behavior. Several investigators have challenged the
general perception of mental illness as one of the leading causes of violent behavior by emphasizing the need
to take other factors into account, such as a history of
violent behavior or societal and environmental stressors associated with mental illness (37–39).
The primary limitations of this study pertain to the
use of existing records that did not include all potentially useful information. First, CHARS data for the index
years in this investigation did not include information
on race. Prior commentary suggests that among explanatory predictors of crime, the most salient are environmental and socioeconomic factors rather than individual characteristics, such as race, and that the
burden of FRHs and death is substantially greater
among disadvantaged groups (28, 40, 41). We attempted to partially overcome this limitation by controlling for payer status and county of hospital in our
analyses. Second, because of the nature of the data-

bases we used, we did not know whether patients continued to reside in Washington after their index hospitalization discharge; therefore, rates of subsequent
hospitalization, death, and arrest have likely been underestimated. Residential mobility is associated with
poverty and crime (42); therefore, outcome rates may
have been particularly underestimated among persons
with prior criminality in this investigation. Third, the
probabilistic linkage of records may have missed true
matches or erroneously created false ones; however,
we restricted the analytic database to matches with a
high likelihood of accuracy to minimize concerns about
misclassification. Fourth, the determination of psychiatric disorder was based on chart diagnosis using ICD-9
codes rather than chart review. It is possible that a fraction of patients with mental illness did not receive a
diagnosis of psychiatric disorder in the hospital setting;
therefore, our findings should not be interpreted as
pertaining to all persons with mental illness. Likewise,
subsequent violent victimization was measured using
hospitalization and death records and did not include
incidents that had not resulted in an inpatient medical
encounter or death. Patients who sustained a firearmrelated injury with no hospitalization records or those
who committed a crime that did not result in an arrest
did not contribute information to events of interest in
the analyses. Finally, selection bias may have been introduced because one basis for comparison was other
hospitalized patients whose propensity for subsequent
injury, death, or crime perpetration may not be representative of that in the underlying population. As such,
we also compared the rates of injury and death among
patients with an FRH and persons in the general population of Washington to provide another basis for
comparison.
This investigation builds and expands on the existing body of knowledge by providing evidence on the
connection between firearm-related injury and subsequent violent victimization or crime perpetration
among hospitalized patients. One avenue for further
research is to operationalize a collaborative intervention, considering that FRH can potentially play an important role in identifying and reaching high-risk persons. Those already involved in a cycle of violence who

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Annals of Internal Medicine • Vol. 162 No. 7 • 7 April 2015 497

 ORIGINAL RESEARCH

Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

Cumulative Incidence of

Firearm-Related Hospitalization

Figure 2. Cumulative incidence of primary outcomes after index hospitalization discharge.
0.10

Type of Index Hospitalization
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

0.08
0.06
0.04
0.02
0
0

At risk, n
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

2

4

6

Years From Index Hospitalization Discharge
609
2447
5644
59 487
168 481

539
2174
4613
47 260
135 126

500
2064
4179
41 879
118 861

484
1970
3907
38 304
107 943

2

4

6

Firearm-Related Death

Cumulative Incidence of

0.10
0.08
0.06
0.04
0.02
0
0

Cumulative Incidence of

Firearm- or Violence-Related Arrest

At risk, n
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

Years From Index Hospitalization Discharge
613
2461
5697
62 464
176 694

596
2407
5478
53 295
160 693

592
2398
5423
51 886
154 127

591
2393
5400
51 325
149 072

2

4

6

0.50
0.40
0.30
0.20
0.10
0
0

At risk, n
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

Years From Index Hospitalization Discharge
613
2461
5697
62 464
176 694

410
1714
4640
50 126
157 877

376
1494
4285
47 467
150 109

351
1394
4081
46 060
144 072

Top. Firearm-related hospitalization. Middle. Firearm-related death. Bottom. Firearm- or violence-related arrest.

498 Annals of Internal Medicine • Vol. 162 No. 7 • 7 April 2015

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 Violent Injury, Death, or Crime Perpetration After Firearm-Related Hospitalization

ORIGINAL RESEARCH

Table 3. sHRs of Violence-Related Hospitalization, Arrest, or Death After Discharge, by Type of Index Hospitalization*
Index
Hospitalization

Hospitalization
Firearm
(Any Intent)

Nonfirearm

Assault
Violent injury
(n = 8655)
Firearm
(n = 613)
Nonfirearm,
assault
(n = 2453)
Nonfirearm,
self-inflicted
(n = 5589)
Nonviolent
injury
(n = 62 428)
Noninjury
(n = 175 039)

Arrest
FirearmRelated or
Violent
Crime

Nonfirearm
Nonviolent
Crime

Death
Firearm
(Any Intent)

Self-Inflicted

Nonfirearm

Assault

0 (0–NE)

Self-Inflicted

21.2 (7.0–64.0)

7.3 (3.5–14.9)

1.7 (0.5–5.3)

2.7 (2.0–3.5)

1.9 (1.6–2.3)

4.3 (1.3–14.1)

3.0 (0.7–12.6)

3.1 (0.9–10.3)

6.6 (4.0–10.7)

2.1 (1.3–3.5)

2.0 (1.7–2.4)

2.0 (1.9–2.2)

0.7 (0.2–2.7)

4.6 (0.8–25.8)

0.7 (0.2–2.9)

0.8 (0.1–5.8)

1.6 (0.8–3.3)

11.9 (9.5–14.8)

2.4 (2.1–2.8)

1.7 (1.6–1.8)

4.1 (2.3–7.3)

5.5 (1.1–27.8)

10.6 (6.8–16.6)

1.7 (0.8–3.8)

2.5 (1.7–3.5)

2.1 (1.7–2.6)

1.4 (1.3–1.6)

1.6 (1.5–1.6)

1.4 (1.0–1.9)

2.3 (0.8–7.0)

1.0 (0.7–1.4)

1.0 (reference)

1.0 (reference)

1.0 (reference)

1.0 (reference)

1.0 (reference)

1.0 (reference)

1.0 (reference)

1.0 (reference)

NE = not estimated; sHR = subhazard ratio.
* Values are sHRs (95% CIs), which were determined by using models that also included age, sex, payer status, discharge year and season, county
of the hospital, history of diagnosis of psychiatric disorder, and history of arrest. A total of 1807 patients with missing data on sex or discharge
season were excluded from these analyses.

have a medical encounter may benefit from interventions to change a trajectory that would otherwise result
in subsequent violent injury, death, or crime perpetration. Secondary and tertiary prevention measures may
begin in the outpatient, emergency department, or inpatient setting and continue afterward in conjunction
with community services and assistance from law enforcement to offer counseling on avoiding repeated injury and new criminal activity (43– 45). These interventions should ideally be multicomponent and address
pathophysiologic, behavioral, and social determinants
of morbidity and mortality in this group of patients (46).
In conclusion, findings of this study indicate that
hospitalization for a firearm-related injury is associated
with a heightened risk for subsequent violent victimization or crime perpetration. Among hospitalized patients, prior criminality has a stronger association with
subsequent violent crime perpetration than a prior diagnosis of mental illness. Further research at the intersection of clinical care, the criminal justice system, and
public health to design and evaluate the feasibility and
effectiveness of interventions delivered to survivors of
firearm-related injury is warranted.
From the University of Washington, Seattle, Washington.
Acknowledgment: The authors thank Jeffrey Love of the Harborview Injury Prevention & Research Center at the University
of Washington; Bill O’Brien of the Department of Epidemiology at the University of Washington; Jennifer Sabel, PhD, of
the Washington State Department of Health; Kanwar Thind of
the University of Washington; and other colleagues at the
Washington State Department of Health, Washington State
Patrol, and Washington State Administrative Office of the
Courts for their contributions to this project. They also thank
Noel Weiss, MD, DPH, of the Department of Epidemiology at
the University of Washington for his critical review of the
manuscript.

Financial Support: By the Seattle City Council and the Univer-

sity of Washington Royalty Research Fund.
Disclosures: Disclosures can be viewed at www.acponline.

org/authors/icmje/ConflictOfInterestForms.do?msNum=M14
-2362.
Reproducible Research Statement: Study protocol and data

set: Not available. Statistical code: Available from Dr.
Rowhani-Rahbar (e-mail, rowhani@uw.edu).
Requests for Single Reprints: Ali Rowhani-Rahbar, MD, MPH,

PhD, Department of Epidemiology, University of Washington,
Box 357236, Seattle, WA 98195.
Current author addresses and author contributions are available at www.annals.org.

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 Annals of Internal Medicine
Current Author Addresses: Dr. Rowhani-Rahbar and Ms. Mills:
Department of Epidemiology, University of Washington, Box
357236, Seattle, WA 98195.
Dr. Zatzick: Department of Psychiatry & Behavioral Sciences,
University of Washington, 325 Ninth Avenue, Box 359911, Seattle, WA 98104.
Drs. Wang and Rivara: Harborview Injury Prevention & Research Center, University of Washington, 325 Ninth Avenue,
Box 359960, Seattle, WA 98104.
Dr. Simonetti: Veterans Affairs Puget Sound Health Care System, 1100 Olive Way, Suite 1400, Seattle, WA 98101.
Dr. Fan: University of Washington School of Law, Gates Hall,
Room 315, Box 353020, Seattle, WA 98195.
Author Contributions: Conception and design: A. RowhaniRahbar, D. Zatzick, F.P. Rivara.
Analysis and interpretation of the data: A. Rowhani-Rahbar, D.
Zatzick, J. Wang, B.M. Mills, J.A. Simonetti, M.D. Fan, F.P.
Rivara.
Drafting of the article: A. Rowhani-Rahbar, D. Zatzick, B.M.
Mills, J.A. Simonetti, M.D. Fan, F.P. Rivara.
Critical revision of the article for important intellectual content: A. Rowhani-Rahbar, D. Zatzick, J. Wang, B.M. Mills, J.A.
Simonetti, M.D. Fan, F.P. Rivara.
Final approval of the article: A. Rowhani-Rahbar, D. Zatzick, J.
Wang, B.M. Mills, J.A. Simonetti, M.D. Fan, F.P. Rivara.
Provision of study materials or patients: A. Rowhani-Rahbar, D.
Zatzick, F.P. Rivara.
Statistical expertise: A. Rowhani-Rahbar, D. Zatzick, J. Wang,
B.M. Mills.
Obtaining of funding: A. Rowhani-Rahbar, D. Zatzick, F.P.
Rivara.
Administrative, technical, or logistic support: A. RowhaniRahbar, D. Zatzick, B.M. Mills, M.D. Fan, F.P. Rivara.
Collection and assembly of data: A. Rowhani-Rahbar, D. Zatzick, F.P. Rivara.

APPENDIX: DATA LINKAGE PROCESS
The focus in building an analytic data set for this
project was to identify records of patients hospitalized
with an injury in 2006 to 2007 in CHARS along with a
comparison group of noninjury admissions in those
years (index hospitalization). Subsequently, patients' index hospitalization record was linked to their prior and
subsequent hospitalization records in CHARS databases, arrest records in Washington State Patrol (WSP)
databases, and conviction records in Washington State
Administrative Office of the Courts (AOC) databases.
Death records in Washington State Vital Records databases were also linked.
The project included many linkages, the first and
most necessary of which involved creating a Washington State Longitudinal Hospital Admissions (WSLHA)
data set, which identified and linked all potential admissions per patient in CHARS. The first approach was a
deterministic linkage in which values in variables between the 2 tables were compared and a hierarchical
“match” value was created. A common term for linkage
procedure is “blocking,” whereby specific variables are
required to match exactly, and then other variables

which may not be exactly equal are compared. The resulting “match” variable had values such as the following for eventual linked records:
1 – Last Name (LN) + First Name (FN) + Date of
Birth (DOB) + Sex + ZIP
2 – Last Name (LN) + First Name (FN) + Date of
Birth (DOB) + Sex (missing) + ZIP
So, for “match = 1”, all variables matched exactly.
This is as good as it gets. For “match = 2”, sex was
missing, but all other variables matched exactly. Along
with the main “match” variable, other separate variables
were created, such as “lmat” for Last Name. A “soundex” code was created for name variables, so that:
lmat =
1 – Exact Last Name
2 – Soundex + Last Name
3 – Last Name contains Last Name (i.e. SMITHJONES to JONES)
4 – One character off (i.e., Connell to Conell)
5–...
For these, the “match” variable might have a value
such as:
21 – Last Name (lmat = 3) + First Name + DOB +
sex + ZIP
Once blocking for one variable was complete,
blocking on another variable was used to look at differences with the first linkage variable. This hierarchical
technique continued such that in some linkages the values in “match” were in the hundreds. Along with the
deterministic linkages described earlier, probabilistic
linkages were implemented. Variables, such as Last
Name (LN_per), First Name (FN_per), and ZIP (ZP_per),
were created based on the percentage of each value as
a whole (that is, 200 000 records; Last Name = Jones
1000 times; LN_per = 0.05). These new variables were
then used to confirm linkages that may otherwise have
been ignored. The hierarchy was used to make a determination on the threshold for excluding records. In this
investigation, we excluded records with less than 99%
probability of a true match.
CHARS data before 2009 had limited identifiers,
primarily LN, FN, DOB, sex, and ZIP code of residence
(that is, block of LNFN + DOB + Sex + ZIP). In 2009, the
addition of full names and a partial social security number (SSN) greatly enhanced the linkage results. WSLHA
was created in 2 steps. The first step included linkage
of all CHARS records for 1987 to 2012 using the limited
identifiers available. The second involved linkage only
for CHARS records where the full names and SSNs were
available. Considering the limited population of Washington, an exact match of the linkage variables created
a highly secure final result (beta_2). The criteria and
results from “beta_1” were then compared to that of
“beta_2”. Linkages from “beta_1” that were determined
to be insufficient for “beta_2” were excluded from
“beta_1” along with all other records from “beta_1” with

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 the same matching criteria as those exclusions. The remaining “beta_1” and “beta_2” files were then united to
create WSLHA. This dual-step process was repeated
later for death, WSP, and AOC linkages.
Admissions in 2006 to 2007 in CHARS for patients
with an injury identified by the ICD-9 E code formed
index hospitalization records of the injury group. Similarly, a comparison group without an injury code frequency matched to the injury group by age in 5-year
categories and year of admission was created. The 2
aforementioned data sets created the original working
data set (mast1). WSLHA was used to identify only 1
admission per patient and to ensure that the comparison group did not include secondary admissions of the
injury group. All prior and subsequent admissions to
records in “mast1” were then identified to create
“mast2,” again using WSLHA. The last admission per
patient was identified using “mast2” for those with a
subsequent admission after “mast1,” and using “mast1”
when no subsequent admission was found. This process created “mast3,” which was then linked to death
records by using all available identifying variables. The
linkage to death records was robust; some of the later
admissions included full names, and some others identified the discharge status as a death; so, the addition

of death dates to CHARS dates greatly enhanced the
linkage.
One data set for WSP and another for AOC records
with all pertinent variables was prepared and linked to
CHARS (mast1) variables using the same linkage variables as previously mentioned. Once the WSP and
AOC data sets were linked, the dual-step process described earlier with WSLHA was repeated on the linkages. Eventually all linkages were combined with
“mast1” and a subsequent final “master” data set was
created, including other CHARS admissions from
“mast2.” In all linkages, more weight was given to less
common LNFN and less common ZIP codes in the
probabilistic hierarchy.
Link Plus, a probabilistic record linkage program
developed at the Centers for Disease Control and Prevention, was used and results were compared against
those obtained from programming in FoxPro (Microsoft) to improve the linkage process. One data programmer performed all data linkages. No protected
health information was sent to the analysis team. To
allow analysis based on the exact time of events, we
created variables to identify the number of days between events, eliminating the need for specific dates
entirely.

Annals of Internal Medicine • Vol. 162 No. 7 • 7 April 2015

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 0.04
0.02
0
0

2

4

6

0.1

Assault-Related Death

Cumulative Incidence of Nonfirearm

Years From Index Hospitalization Discharge

0.08
0.06
0.04
0.02
0
0

2

4

6

Years From Index Hospitalization Discharge

Cumulative Incidence of Nonfirearm,

0.06

Self-Inflicted, Injury-Related Hospitalization

Type of Index Hospitalization
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

0.08

Self-Inflicted, Injury-Related Death

0.1

Appendix Figure 2. Cumulative incidence of nonfirearm,
self-inflicted, injury-related hospitalization (top) and
nonfirearm, self-inflicted, injury-related death (bottom)
after index hospitalization discharge.

Cumulative Incidence of Nonfirearm,

Assault-Related Hospitalization

Cumulative Incidence of Nonfirearm

Appendix Figure 1. Cumulative incidence of nonfirearm
assault-related hospitalization (top) and nonfirearm
assault-related death (bottom) after index hospitalization
discharge.

Type of Index Hospitalization
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

0.1
0.08
0.06
0.04
0.02
0
0

2

4

6

Years From Index Hospitalization Discharge

0.1
0.08
0.06
0.04
0.02
0
0

2

4

6

Years From Index Hospitalization Discharge

1.0

Nonviolent Arrest

Cumulative Incidence of Nonfirearm

Appendix Figure 3. Cumulative incidence of nonfirearm
nonviolent arrest after index hospitalization discharge.

Type of Index Hospitalization
Firearm
Nonfirearm, assault
Nonfirearm, self-inflicted
Nonfirearm, unintentional
Noninjury

0.8
0.6
0.4
0.2
0
0

2

4

6

Years From Index Hospitalization Discharge

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20.5 (6.8–61.9)
3.0 (0.9–10.0)
0.7 (0.1–5.8)
1.7 (0.8–3.7)
1.0 (reference)

Firearm
(Any Intent)

7.1 (3.5–14.6)
6.4 (3.9–10.4)
1.6 (0.8–3.2)
2.4 (1.7–3.5)
1.0 (reference)

Assault
1.7 (0.5–5.3)
2.1 (1.3–3.5)
11.8 (9.4–14.7)
2.1 (1.7–2.5)
1.0 (reference)

Self-Inflicted

Nonfirearm

Hospitalization

2.6 (1.9–3.4)
2.0 (1.7–2.3)
2.4 (2.1–2.7)
1.4 (1.3–1.5)
1.0 (reference)

Firearm-Related
or Violent Crime

Arrest

1.9 (1.5–2.2)
2.0 (1.8–2.2)
1.7 (1.5–1.9)
1.5 (1.4–1.6)
1.0 (reference)

Nonfirearm
Nonviolent
Crime

4.2 (1.3–13.7)
0.7 (0.2–2.6)
4.0 (2.2–7.2)
1.4 (1.0–1.9)
1.0 (reference)

Firearm
(Any Intent)

3.1 (0.7–13.1)
0.7 (0.2–2.8)
10.4 (6.7–16.4)
0.9 (0.6–1.4)
1.0 (reference)

Self-Inflicted

Nonfirearm

0 (0–NE)
4.3 (0.8–24.0)
5.4 (1.1–26.7)
2.3 (0.7–6.9)
1.0 (reference)

Assault

Death

3.8 (2.7–5.5)
1.0 (reference)

1.5 (0.6–3.9)
1.0 (reference)

1.5 (0.7–3.3)
1.5 (0.4–5.3)
1.0 (reference)

History of diagnosis of psychiatric disorder
Substance use disorders (n = 46 236)
Other psychiatric disorders (n = 37 187)
None (n = 162 699)

5.9 (4.7–7.4)
5.8 (4.5–7.5)
1.0 (reference)

1.6 (1.3–1.9)
1.0 (reference)

1.3 (1.0–1.7)
1.0 (reference)

Self-Inflicted

2.2 (2.0–2.4)
1.7 (1.5–1.9)
1.0 (reference)

4.2 (3.7–4.6)
1.0 (reference)

3.8 (3.4–4.2)
1.0 (reference)

Firearm-Related
or Violent Crime

Arrest

2.7 (2.6–2.8)
1.4 (1.3–1.5)
1.0 (reference)

8.9 (8.5–9.4)
1.0 (reference)

1.7 (1.6–1.8)
1.0 (reference)

Nonfirearm
Nonviolent
Crime

2.3 (1.6–3.4)
1.7 (1.1–2.6)
1.0 (reference)

1.1 (0.7–1.9)
1.0 (reference)

1.1 (0.5–2.1)
1.0 (reference)

Firearm
(Any Intent)

1.0 (0.3–2.9)
0.7 (0.1–3.4)
1.0 (reference)

1.3 (0.3–6.4)
1.0 (reference)

3.8 (2.6–5.6)
3.7 (2.4–5.7)
1.0 (reference)

1.1 (0.7–1.8)
1.0 (reference)

1.8 (1.1–3.0)
1.0 (reference)

Self-Inflicted

Nonfirearm

12.0 (2.8–51.9)
1.0 (reference)

Assault

Death

sHR = subhazard ratio.
* Values are sHRs (95% CIs), which were determined by using models that also included variables listed in the table and age, sex, payer status, discharge year and season, county of the hospital,
and type of index hospitalization. A total of 1807 patients with missing data on sex or discharge season were excluded from these analyses.

2.7 (1.9–3.7)
1.6 (0.9–2.8)
1.0 (reference)

1.3 (0.9–1.8)
1.0 (reference)

Assault

Nonfirearm

3.3 (1.3–8.3)
1.0 (reference)

Firearm
(Any Intent)

Hospitalization

History of arrest
Firearm-related or violent crime
Yes (n = 5529)
No (n = 240 593)
Nonfirearm nonviolent crime
Yes (n = 14 698)
No (n = 231 424)

Variable

Appendix Table 2. sHRs of Violence-Related Hospitalization, Arrest, or Death After Discharge, by History and Type of Arrest and Psychiatric Disorder Diagnosis*

NE = not estimated; sHR = subhazard ratio.
* Values are sHRs (95% CIs), which were determined by using models that also included age, sex, payer status, discharge year and season, county of the hospital, history of diagnosis of psychiatric
disorder, and history of arrest and conviction. A total of 1807 patients with missing data on sex or discharge season were excluded from these analyses.

Violent injury (n = 8655)
Firearm (n = 613)
Nonfirearm, assault (n = 2453)
Nonfirearm, self-inflicted (n = 5589)
Nonviolent injury (n = 62 428)
Noninjury (n = 175 039)

Index Hospitalization

Appendix Table 1. sHRs of Violence-Related Hospitalization, Arrest, or Death After Discharge, by Type of Index Hospitalization and Controlled for History of Arrest and
Conviction*