OBJECTIVES:

Among adolescents and young adults with nonfatal self-harm, our objective is to identify risk factors for repeated nonfatal self-harm and suicide death over the following year.

METHODS:

A national cohort of patients in the Medicaid program, aged 12 to 24 years (n = 32 395), was followed for up to 1 year after self-harm. Cause of death information was obtained from the National Death Index. Repeat self-harm per 1000 person-years and suicide deaths per 100 000 person-years were determined. Hazard ratios (HRs) of repeat self-harm and suicide were estimated by Cox proportional hazard models. Suicide standardized mortality rate ratios were derived by comparison with demographically matched general population controls.

RESULTS:

The 12-month suicide standardized mortality rate ratio after self-harm was significantly higher for adolescents (46.0, 95% confidence interval [CI]: 29.9–67.9) than young adults (19.2, 95% CI: 12.7–28.0). Hazards of suicide after self-harm were significantly higher for American Indians and Alaskan natives than non-Hispanic white patients (HR: 4.69, 95% CI: 2.41–9.13) and for self-harm patients who initially used violent methods (HR: 18.04, 95% CI: 9.92–32.80), especially firearms (HR: 35.73, 95% CI: 15.42–82.79), compared with nonviolent self-harm methods (1.00, reference). The hazards of repeat self-harm were higher for female subjects than male subjects (HR: 1.25, 95% CI: 1.18–1.33); patients with personality disorders (HR: 1.55, 95% CI: 1.42–1.69); and patients whose initial self-harm was treated in an inpatient setting (HR: 1.65, 95% CI: 1.49–1.83) compared with an emergency department (HR: 0.62, 95% CI: 0.55–0.69) or outpatient (1.00, reference) setting.

CONCLUSIONS:

After nonfatal self-harm, adolescents and young adults were at markedly elevated risk of suicide. Among these high-risk patients, those who used violent self-harm methods, particularly firearms, were at especially high risk underscoring the importance of follow-up care to help ensure their safety.

What’s Known on This Subject:

Although nonfatal self-harm is common among young people and suicide is a leading cause of death among adolescents and young adults, little is known about the rate and risks of suicide after nonfatal self-harm in young people.

What This Study Adds:

After self-harm, adolescents and young adults were at markedly increased risk of suicide, including especially those who initially used violent self-harm methods or were of American Indian or Alaskan native descent. These risks highlight the importance of close follow-up after self-harm events.

Nonfatal self-harm, which may involve varying degrees of suicidal intent, is common in young people,1 and suicide is the second leading cause of death in the United States among people ages 15 to 24 years.2 Because nearly one-third of young people who die of suicide have nonfatal self-harm events during the last 3 months of life,3 self-harm may offer opportunities for potentially life-saving interventions.

In contrast to suicide attempts, which require suicidal intent, self-harm refers to nonfatal self-poisoning or self-injury with or without suicidal intent.4 After self-harm, adolescents are at risk for repeat self-harm and suicide.5 An important challenge is to assess suicide risk after nonfatal self-harm. The authors of three previous cohort studies have evaluated suicide risk during the first year after self-harm in young people. The authors of a UK study, who followed 5414 patients ages 10 to 24 years after self-harm, reported that 0.3% (n = 15) died of suicide in the first follow-up year.6 More recently, the authors of a Swedish study of 8387 self-harm patients ages 10 to 19 years reported that 0.16% (n = 13) died by suicide in the first year.7 The authors of a recent Canadian study, who followed 20 471 adolescents after emergency department treatment of self-poisoning, reported that their hazard of suicide during the first follow-up year was 32.1 times greater than matched controls.8 In the current study, we extend this line of research to a large US sample of Medicaid-insured young people after nonfatal self-harm.

Repetition of self-harm is also clinically important because it is associated with an increased risk of suicide,9 indicates persistent distress, and places demands on health care resources.10 Risk factors for repeated self-harm in young people include a history of previous self-harm,11,12 previous mental health treatment,13 a violent method of self-harm,14 and specific psychiatric disorders including depression,15,20 substance use disorders,11,15,21,22 anxiety disorders,11,15,16 schizophrenia,16,22 attention-deficit/hyperactivity disorder (ADHD),16,22 and personality disorders.16,20 Because of variation in study samples and designs, however, the relative strength of these patient characteristics on risk of repeat self-harm remains poorly defined.

Age-related changes in cognitive, affective, social, behavioral, and biological vulnerabilities may influence initiation and persistence of psychopathology through adolescence and young adulthood.23,24 However, little is known about whether and how adolescents and young adults vary in their risks of repeated self-harm and suicide after self-harm. To address these issues, we compared adolescents and young adults with respect to these risks after self-harm. In accordance with overall suicide risk,25 we anticipated that older age, male sex, and non-Hispanic white race and/or ethnicity would be related to increased suicide risk after self-harm.

A self-harm cohort was extracted from 2001 to 2007 national (45 states, not including AZ, DE, NV, OR, or RI) Medicaid Analytic Extract data, which includes claims records for Medicaid-financed services and medications. Dates and cause of death information were derived from linkage to the National Death Index, which is the most complete resource available for tracing mortality in national samples.26 US population death rates in 2001–2007 were derived from the National Center for Health Statistics.25 This project was approved by the Rutgers University Institutional Review Board.

The cohort was restricted to individuals 12 to 24 years of age with clinical diagnoses of deliberate self-harm (International Classification of Diseases, Ninth Revision, Clinical Modification codes E950–E958). Patients were also required to be eligible for Medicaid services during the 180 days preceding their index self-harm event.

The first eligible instance of self-harm was selected, and no patient contributed more than 1 observation. The cohort was followed forward from their index self-harm until the end of a 365-day follow-up period, date of death, or end of available data, whichever came first. For self-harms treated in outpatient or emergency department settings, the index date was the date of self-harm treatment. For self-harms treated in inpatient settings, the index date was the hospital discharge date.27 

Following the Centers for Disease Control and Prevention, suicide was defined as International Classification of Diseases, 10th Revision codes X60–X84, Y87.0, or U03 as the immediate cause of death.28 The primary outcomes of interest were repeat, nonfatal self-harm and suicide deaths. Suicide deaths coinciding with the index self-harm were not included in the analyses. Secondary outcomes included all causes of death and death due to accidents (V01–X59, Y85–Y86).

On the basis of Medicaid eligibility data, cohort members were classified by age at time of the index self-harm as adolescents (12–17 years) or young adults (18–24 years), sex, and race and/or ethnicity: white, non-Hispanic; African American, non-Hispanic; Hispanic; American Indian or Alaskan native; and “other” including Asian Americans, Native Hawaiians or other Pacific Islanders, and more than 1 race. Cohort members were also classified by geographic region (west, midwest, south, northeast), and Medicaid eligibility status (disability, foster care, low income, or other).

Variables representing clinical diagnoses on or within 180 days before the index self-harm were defined for ADHD, disruptive behavior disorders, depressive disorders, bipolar disorder, anxiety disorders, schizophrenia and related psychoses, substance use disorders, personality disorders, and a residual group of other mental disorders (Supplemental Table 6). At least 1 inpatient or 2 outpatient diagnoses defined each mental disorder group.29 In analysis of these diagnostic groups, comparators were self-harm patients without the disorder of interest. A separate variable defined the number of mental health diagnostic groups (0, 1, 2, 3+). Separate variables defined any inpatient and outpatient mental health care and any outpatient care during the 180 days preceding the self-harm event.

Place of service codes were used to classify the index self-harm treatment setting hierarchically as (1) inpatient, (2) emergency department, or (3) outpatient for those receiving care in >1 setting. Index self-harm method was classified as violent, nonviolent, and other methods with external cause of injury codes (E-codes). Nonviolent methods were subclassified as cutting, poisoning, or other methods. Violent methods included firearms and other violent methods (drowning, hanging and suffocation, jumping from heights, motor vehicle or aircraft crashing, fire and scalding, and extreme cold) (Supplemental Table 6).30,31 

Adolescents and young adults who were treated for nonfatal self-harm were compared with respect to demographic and clinical characteristics. For each demographic and clinical variable stratum, we determined the number of patients, person years of follow-up, number with ≥1 repeat self-harm events, and first repeat self-harm rates per 1000 person-years. Corresponding stratified rates of suicide risk per 100 000 person-years of follow-up were determined. For self-harm patients who survived the initial event, Cox proportional hazard models, which make no assumptions about the baseline hazard, estimated unadjusted hazard ratios (HRs) of repeat self-harm during follow-up with each stratification variable as the independent variable of interest. Adjusted Cox models controlled for age, sex, race and/or ethnicity, geographic region, and Medicaid eligibility status. Separate models were fit for adolescents and young adults. Models also included an interaction term (stratification variable by age group) to assess differences in repeat self-harm risk across the 2 age groups.

For comparison of suicide rates of the self-harm cohort with US population suicide rates, we determined the matched age group, sex, and race and/or ethnicity in the US population annual mean suicide rates for 2001–2007. All statistical analyses were performed with SAS 9.4 (SAS Institute, Inc, Cary, NC).

A total of 32 437 self-harm events were observed. Forty-two (0.13%) were fatal (suicide), including 20 adolescents and 22 young adults, and excluded from the prospective cohort (n = 32 395).

Most patients with nonfatal initial self-harm were white, adolescents, female subjects, and their events involved poisoning (Table 1). Depression and substance use disorders were the most commonly diagnosed mental disorders within the 180 days preceding self-harm. Approximately half of the patients with self-harm were treated in emergency departments, whereas 22.5% involved inpatient admission. As compared with adolescent self-harm patients, young adult self-harm patients were more likely to have been diagnosed with substance use disorders, personality disorders, or schizophrenia and related psychoses and less likely to have been diagnosed with ADHD, other disruptive behavioral disorders, or depression in the 180 days before self-harm. Approximately half of each age group received any outpatient mental health care during this period.

TABLE 1

Background Characteristics of Adolescent and Young Adult Medicaid Patients Treated for Nonfatal, Deliberate Self-Harm

CharacteristicTotal (N = 32 395), %Adolescents 12–17 y (N = 17 427), %Young Adults 18–24 y (N = 14 968), %Odds Ratio of Adolescent Groupa (95% CI)
Sex     
 Male 32.4 31.0 34.1 1.00 
 Female 67.6 69.0 65.9 1.16 (1.10–1.21) 
Race and/or ethnicity     
 White, non-Hispanic 62.3 59.8 65.2 1.00 
 African American, non-Hispanic 16.9 17.0 16.8 1.11 (1.04–1.18) 
 Hispanic 13.1 14.9 11.0 1.49 (1.39–1.60) 
 American Indian or Alaskan native 5.1 5.9 4.2 1.56 (1.40–1.73) 
 Otherb 2.6 2.4 2.8 0.95 (0.82–1.09) 
Recent clinical diagnosesc     
 ADHD 8.9 12.4 4.9 2.68 (2.46–2.94) 
 Disruptive behavior disorders 13.3 19.4 6.2 3.59 (3.32–3.88) 
 Depressive disorders 35.6 37.4 33.5 1.19 (1.14–1.25) 
 Bipolar disorders 13.2 12.5 14.2 0.86 (0.81–0.92) 
 Anxiety disorders 15.4 14.2 16.6 0.84 (0.79–0.89) 
 Schizophrenia and related psychoses 10.0 6.4 14.3 0.41 (0.38–0.45) 
 Substance use disorders 23.3 17.0 30.7 0.47 (0.44–0.49) 
 Personality disorders 7.0 3.8 10.8 0.34 (0.31–0.38) 
 Other mental disorders 7.1 7.9 6.1 1.31 (1.20–1.43) 
No. clinical mental diagnoses     
 0 26.1 26.5 25.6 1.00 
 1 36.8 38.2 35.2 1.06 (1.00–1.12) 
 2 20.9 19.8 22.1 0.89 (0.83–0.95) 
 3+ 16.2 15.5 17.1 0.89 (0.83–0.96) 
Recent inpatient mental health carec 16.9 16.2 17.6 0.93 (0.87–0.98) 
Recent outpatient mental health carec 48.0 48.9 46.9 1.09 (1.04–1.14) 
Self-harm treatment setting     
 Inpatient 24.8 22.5 27.5 0.70 (0.66–0.75) 
 Emergency department 50.7 51.1 50.3 0.87 (0.82–0.92) 
 Outpatient 24.5 26.4 22.2 1.00 
Any recent outpatient care 89.5 89.6 89.3 1.03 (0.95–1.11) 
Self-harm methodd     
 Violent method 4.5 4.7 4.3 1.15 (1.03–1.29) 
  Firearms 0.9 0.6 1.2 0.56 (0.43–0.71) 
  Other violent methods 3.7 4.1 3.1 1.39 (1.22–1.57) 
 Nonviolent method 83.4 81.5 85.7 1.00 
  Poisoning 65.0 63.5 66.7 1.00 
  Cutting 18.4 18.0 18.9 1.02 (0.96–1.08) 
 Other 12.0 13.8 10.0 1.48 (1.38–1.59) 
CharacteristicTotal (N = 32 395), %Adolescents 12–17 y (N = 17 427), %Young Adults 18–24 y (N = 14 968), %Odds Ratio of Adolescent Groupa (95% CI)
Sex     
 Male 32.4 31.0 34.1 1.00 
 Female 67.6 69.0 65.9 1.16 (1.10–1.21) 
Race and/or ethnicity     
 White, non-Hispanic 62.3 59.8 65.2 1.00 
 African American, non-Hispanic 16.9 17.0 16.8 1.11 (1.04–1.18) 
 Hispanic 13.1 14.9 11.0 1.49 (1.39–1.60) 
 American Indian or Alaskan native 5.1 5.9 4.2 1.56 (1.40–1.73) 
 Otherb 2.6 2.4 2.8 0.95 (0.82–1.09) 
Recent clinical diagnosesc     
 ADHD 8.9 12.4 4.9 2.68 (2.46–2.94) 
 Disruptive behavior disorders 13.3 19.4 6.2 3.59 (3.32–3.88) 
 Depressive disorders 35.6 37.4 33.5 1.19 (1.14–1.25) 
 Bipolar disorders 13.2 12.5 14.2 0.86 (0.81–0.92) 
 Anxiety disorders 15.4 14.2 16.6 0.84 (0.79–0.89) 
 Schizophrenia and related psychoses 10.0 6.4 14.3 0.41 (0.38–0.45) 
 Substance use disorders 23.3 17.0 30.7 0.47 (0.44–0.49) 
 Personality disorders 7.0 3.8 10.8 0.34 (0.31–0.38) 
 Other mental disorders 7.1 7.9 6.1 1.31 (1.20–1.43) 
No. clinical mental diagnoses     
 0 26.1 26.5 25.6 1.00 
 1 36.8 38.2 35.2 1.06 (1.00–1.12) 
 2 20.9 19.8 22.1 0.89 (0.83–0.95) 
 3+ 16.2 15.5 17.1 0.89 (0.83–0.96) 
Recent inpatient mental health carec 16.9 16.2 17.6 0.93 (0.87–0.98) 
Recent outpatient mental health carec 48.0 48.9 46.9 1.09 (1.04–1.14) 
Self-harm treatment setting     
 Inpatient 24.8 22.5 27.5 0.70 (0.66–0.75) 
 Emergency department 50.7 51.1 50.3 0.87 (0.82–0.92) 
 Outpatient 24.5 26.4 22.2 1.00 
Any recent outpatient care 89.5 89.6 89.3 1.03 (0.95–1.11) 
Self-harm methodd     
 Violent method 4.5 4.7 4.3 1.15 (1.03–1.29) 
  Firearms 0.9 0.6 1.2 0.56 (0.43–0.71) 
  Other violent methods 3.7 4.1 3.1 1.39 (1.22–1.57) 
 Nonviolent method 83.4 81.5 85.7 1.00 
  Poisoning 65.0 63.5 66.7 1.00 
  Cutting 18.4 18.0 18.9 1.02 (0.96–1.08) 
 Other 12.0 13.8 10.0 1.48 (1.38–1.59) 
a

Young adults are the reference group.

b

Other race and/or ethnicity includes Asian Americans, Native Hawaiians or other Pacific Islanders, and >1 race.

c

During 180-day period before index self-harm visit.

d

Self-harm methods were measured as (1) violent, nonviolent, and other, with nonviolent methods as the reference group and as (2) firearms, other violent methods, poisoning, cutting, and other, with poisoning as the reference group.

Approximately 17.1% (5545 of 32 395) of the self-harm patients had repeated nonfatal self-harm during the follow-up year for an unadjusted repeat self-harm rate of 222.7 per 1000 person-years (Table 2). The cumulative probability of first self-harm distributions were similar for adolescents and young adults, with both having a steep rise in the first few days after the initial event and then rising more gradually (Fig 1).

TABLE 2

Repeat Nonfatal Self-Harm Rates in a Cohort of Adolescent and Young Adult Medicaid Patients During the First Year After a Nonfatal Self-Harm Event

GroupNo. PatientsPerson-y at RiskFirst DSH Events, NUnadjusted DSH Rate (per 1000 Person-y)HR of DSH (95% CI)Adjusted HR of Repeat DSH (95% CI)a
Total 32 395 24 896.1 5545 222.7 N/A N/A 
Age, y       
 12–17 17 427 13 455.6 2889 214.7 1.00 1.00 
 18–24 14 968 11 440.5 2656 232.2 1.07 (1.02–1.13) 1.01 (0.96–1.07) 
Sex       
 Male 10 513 8184.9 1556 190.1 1.00 1.00 
 Female 21 882 16 711.2 3989 238.7 1.25 (1.18–1.33) 1.33 (1.26–1.42) 
Race/ethnicity       
 White, non-Hispanic 19 859 15 087.4 3600 238.6 1.00 1.00 
 African American, non-Hispanic 5400 4272.6 744 174.1 0.75 (0.69–0.81) 0.73 (0.67–0.79) 
 Hispanic 4175 3284.6 644 196.1 0.85 (0.78–0.92) 0.91 (0.83–1.00) 
 American Indian or Alaskan native 1637 1227.1 328 267.3 1.12 (1.00–1.25) 1.18 (1.05–1.32) 
 Otherb 813 647.8 134 206.8 0.90 (0.76–1.07) 0.94 (0.79–1.13) 
Recent clinical diagnosesc       
 ADHD 2897 2151.3 519 241.2 1.05 (0.96–1.15) 1.02 (0.93–1.13) 
 Disruptive behavior disorders 4302 3286.4 814 247.7 1.12 (1.04–1.20) 1.11 (1.03–1.21) 
 Depressive disorders 11 530 8834.2 2076 235.0 1.09 (1.03–1.15) 1.07 (1.02–1.14) 
 Bipolar disorders 4272 3092.2 889 287.5 1.27 (1.19–1.37) 1.16 (1.08–1.25) 
 Anxiety disorders 4974 3609.7 1088 301.4 1.37 (1.28–1.46) 1.24 (1.16–1.33) 
 Schizophrenia and related psychoses 3249 2416.5 680 281.4 1.25 (1.15–1.35) 1.17 (1.08–1.28) 
 Substance use disorders 7552 5588.0 1459 261.1 1.19 (1.12–1.26) 1.15 (1.08–1.22) 
 Personality disorders 2283 1649.1 578 350.5 1.55 (1.42–1.69) 1.36 (1.24–1.49) 
 Other mental disorders 2286 1829.0 335 183.2 0.84 (0.75–0.93) 0.87 (0.78–0.97) 
No. clinical mental diagnoses       
 0 8448 6692.4 1210 180.8 1.00 1.00 
 1 11 935 9276.1 1930 208.1 1.13 (1.05–1.22) 1.07 (0.99–1.15) 
 2 6754 5091.3 1271 249.6 1.32 (1.22–1.43) 1.22 (1.13–1.32) 
 3+ 5258 3836.2 1134 295.6 1.52 (1.40–1.65) 1.36 (1.25–1.48) 
Recent inpatient mental health carec 5462 3982.5 1289 323.7 1.51 (1.42–1.61) 1.42 (1.33–1.51) 
Recent outpatient mental health carec 15 546 11 619.3 3037 261.4 1.33 (1.26–1.40) 1.24 (1.17–1.31) 
Self-harm treatment setting       
 Inpatient 7788 5001.0 2243 448.5 1.94 (1.81–2.08) 1.92 (1.79–2.06) 
 Emergency department 15 930 13 186.9 1875 142.2 0.69 (0.64–0.74) 0.66 (0.61–0.71) 
 Outpatient 7687 5902.2 1263 214.0 1.00 1.00 
Any recent outpatient carec 28 980 22 191.9 5065 228.2 1.25 (1.14–1.37) 1.11 (1.01–1.22) 
Self-harm methodd       
 Violent method 1436 1065.8 226 212.0 0.86 (0.75–0.98) 0.94 (0.82–1.07) 
  Firearms 281 205.2 49 238.8 0.88 (0.67–1.17) 1.07 (0.81–1.43) 
  Other violent methods 1155 860.6 177 205.7 0.77 (0.66–0.89) 0.80 (0.68–0.93) 
 Nonviolent method 26 365 19 985.8 4814 240.9 1.00 1.00 
  Poisoning 20 534 15 337.9 4025 262.4 1.00 1.00 
  Cutting 5831 4647.9 789 169.8 0.65 (0.60–0.70) 0.62 (0.57–0.67) 
 Other 3803 3177.1 405 127.5 0.55 (0.49–0.60) 0.58 (0.52–0.64) 
  Other 3803 3177.1 405 127.5 0.50 (0.45–0.55) 0.52 (0.47–0.57) 
GroupNo. PatientsPerson-y at RiskFirst DSH Events, NUnadjusted DSH Rate (per 1000 Person-y)HR of DSH (95% CI)Adjusted HR of Repeat DSH (95% CI)a
Total 32 395 24 896.1 5545 222.7 N/A N/A 
Age, y       
 12–17 17 427 13 455.6 2889 214.7 1.00 1.00 
 18–24 14 968 11 440.5 2656 232.2 1.07 (1.02–1.13) 1.01 (0.96–1.07) 
Sex       
 Male 10 513 8184.9 1556 190.1 1.00 1.00 
 Female 21 882 16 711.2 3989 238.7 1.25 (1.18–1.33) 1.33 (1.26–1.42) 
Race/ethnicity       
 White, non-Hispanic 19 859 15 087.4 3600 238.6 1.00 1.00 
 African American, non-Hispanic 5400 4272.6 744 174.1 0.75 (0.69–0.81) 0.73 (0.67–0.79) 
 Hispanic 4175 3284.6 644 196.1 0.85 (0.78–0.92) 0.91 (0.83–1.00) 
 American Indian or Alaskan native 1637 1227.1 328 267.3 1.12 (1.00–1.25) 1.18 (1.05–1.32) 
 Otherb 813 647.8 134 206.8 0.90 (0.76–1.07) 0.94 (0.79–1.13) 
Recent clinical diagnosesc       
 ADHD 2897 2151.3 519 241.2 1.05 (0.96–1.15) 1.02 (0.93–1.13) 
 Disruptive behavior disorders 4302 3286.4 814 247.7 1.12 (1.04–1.20) 1.11 (1.03–1.21) 
 Depressive disorders 11 530 8834.2 2076 235.0 1.09 (1.03–1.15) 1.07 (1.02–1.14) 
 Bipolar disorders 4272 3092.2 889 287.5 1.27 (1.19–1.37) 1.16 (1.08–1.25) 
 Anxiety disorders 4974 3609.7 1088 301.4 1.37 (1.28–1.46) 1.24 (1.16–1.33) 
 Schizophrenia and related psychoses 3249 2416.5 680 281.4 1.25 (1.15–1.35) 1.17 (1.08–1.28) 
 Substance use disorders 7552 5588.0 1459 261.1 1.19 (1.12–1.26) 1.15 (1.08–1.22) 
 Personality disorders 2283 1649.1 578 350.5 1.55 (1.42–1.69) 1.36 (1.24–1.49) 
 Other mental disorders 2286 1829.0 335 183.2 0.84 (0.75–0.93) 0.87 (0.78–0.97) 
No. clinical mental diagnoses       
 0 8448 6692.4 1210 180.8 1.00 1.00 
 1 11 935 9276.1 1930 208.1 1.13 (1.05–1.22) 1.07 (0.99–1.15) 
 2 6754 5091.3 1271 249.6 1.32 (1.22–1.43) 1.22 (1.13–1.32) 
 3+ 5258 3836.2 1134 295.6 1.52 (1.40–1.65) 1.36 (1.25–1.48) 
Recent inpatient mental health carec 5462 3982.5 1289 323.7 1.51 (1.42–1.61) 1.42 (1.33–1.51) 
Recent outpatient mental health carec 15 546 11 619.3 3037 261.4 1.33 (1.26–1.40) 1.24 (1.17–1.31) 
Self-harm treatment setting       
 Inpatient 7788 5001.0 2243 448.5 1.94 (1.81–2.08) 1.92 (1.79–2.06) 
 Emergency department 15 930 13 186.9 1875 142.2 0.69 (0.64–0.74) 0.66 (0.61–0.71) 
 Outpatient 7687 5902.2 1263 214.0 1.00 1.00 
Any recent outpatient carec 28 980 22 191.9 5065 228.2 1.25 (1.14–1.37) 1.11 (1.01–1.22) 
Self-harm methodd       
 Violent method 1436 1065.8 226 212.0 0.86 (0.75–0.98) 0.94 (0.82–1.07) 
  Firearms 281 205.2 49 238.8 0.88 (0.67–1.17) 1.07 (0.81–1.43) 
  Other violent methods 1155 860.6 177 205.7 0.77 (0.66–0.89) 0.80 (0.68–0.93) 
 Nonviolent method 26 365 19 985.8 4814 240.9 1.00 1.00 
  Poisoning 20 534 15 337.9 4025 262.4 1.00 1.00 
  Cutting 5831 4647.9 789 169.8 0.65 (0.60–0.70) 0.62 (0.57–0.67) 
 Other 3803 3177.1 405 127.5 0.55 (0.49–0.60) 0.58 (0.52–0.64) 
  Other 3803 3177.1 405 127.5 0.50 (0.45–0.55) 0.52 (0.47–0.57) 

DSH, deliberate self-harm; N/A, not applicable.

a

Adjusted HRs are from models that control for age, sex, race and/or ethnicity, geographic region, and Medicaid eligibility status.

b

Other race and/or ethnicity includes Asian Americans, Native Hawaiians or other Pacific Islanders, and >1 race.

c

During 180-day period before index self-harm visit.

d

Self-harm methods were measured as (1) violent, nonviolent, and other, with nonviolent methods as the reference group and as (2) firearms, other violent methods, poisoning, cutting, and other, with poisoning as the reference group.

FIGURE 1

Cumulative probability of repeated self-harm during the 365 days after a self-harm event of adolescents and young adults. Log-rank test χ2 = 0.68, P = .41.

FIGURE 1

Cumulative probability of repeated self-harm during the 365 days after a self-harm event of adolescents and young adults. Log-rank test χ2 = 0.68, P = .41.

Close modal

The unadjusted hazards of repeat nonfatal self-harm were higher for young adults than adolescents, female than male patients, and white than African American or Hispanic patients, although the age group difference was not evident in the adjusted model. Recent clinical diagnoses of each specific mental disorder other than ADHD were also associated with significantly increased hazards of repeated self-harm. The hazards also increased with increasing number of mental disorders. The risk of repeat self-harm was significantly higher for patients treated for personality or anxiety disorders than depressive disorders. Self-harm events that involved poisoning or that were treated in inpatient settings were also associated with increased risk of repeated self-harm.

There were few differences between adolescents and young adults in risk factors of repeated self-harm. However, female sex, Hispanic ethnicity, and treatment of the initial self-harm in an inpatient setting were more strongly associated with repeat self-harm for adolescents than for young adults (Table 3). By contrast, a recent diagnosis of disruptive behavior disorders or schizophrenia and the number of mental disorder diagnoses were more strongly associated with repeat self-harm for young adults than adolescents.

TABLE 3

Cox Proportional Hazards Regression Models of Repeat Deliberate Nonfatal Self-Harm After Deliberate Self-Harm Events for Adolescent and Young Adult Medicaid Patients

CharacteristicAdolescents Adjusteda HR (95% CI)Young Adults Adjusteda HR (95% CI)Interaction P
Sex    
 Male 1.00 1.00 N/A 
 Female 1.44 (1.32–1.57) 1.23 (1.13–1.34) .001 
Race and/or ethnicity    
 White, non-Hispanic 1.00 1.00 N/A 
 African American, non-Hispanic 0.74 (0.66–0.82) 0.74 (0.66–0.83) .92 
 Hispanic 0.95 (0.85–1.07) 0.84 (0.73–0.98) .02 
 American Indian or Alaskan native 1.24 (1.08–1.44) 1.08 (0.90–1.31) .17 
 Otherb 0.91 (0.70–1.17) 0.99 (0.78–1.26) .78 
Recent clinical diagnosesc    
 ADHD 1.05 (0.94–1.18) 1.08 (0.91–1.27) .14 
 Disruptive behavior disorders 1.08 (0.99–1.19) 1.27 (1.10–1.46) .005 
 Depressive disorders 1.03 (0.95–1.11) 1.12 (1.04–1.22) .19 
 Bipolar disorders 1.24 (1.12– 1.38) 1.11 (1.00–1.23) .53 
 Anxiety disorders 1.18 (1.07–1.31) 1.30 (1.18–1.43) .10 
 Schizophrenia and related psychoses 0.95 (0.81–1.11) 1.26 (1.14–1.40) .0002 
 Substance use disorders 1.11 (1.01–1.22) 1.16 (1.07–1.26) .31 
 Personality disorders 1.22 (1.03–1.44) 1.40 (1.25–1.56) .09 
 Other mental disorders 0.91 (0.79–1.05) 0.80 (0.66–0.95) .17 
No. clinical mental diagnoses    
 0 1.00 1.00 N/A 
 1 1.04 (0.94–1.15) 1.11 (0.99–1.24) .26 
 2 1.14 (1.02–1.27) 1.33 (1.18–1.50) .01 
 3+ 1.21 (1.07–1.36) 1.55 (1.36–1.75) <.0001 
Recent inpatient mental health carec 1.37 (1.25–1.51) 1.44 (1.31–1.58) .10 
Recent outpatient mental health carec 1.22 (1.13–1.32) 1.26 (1.16–1.37) .03 
Self-harm treatment setting    
 Inpatient 2.16 (1.96–2.38) 1.65 (1.49–1.83) .0002 
 Emergency department 0.69 (0.63–0.77) 0.62 (0.55–0.69) .12 
 Outpatient 1.00 1.00 N/A 
Any recent outpatient carec 1.05 (0.92–1.19) 1.20 (1.04–1.39) .08 
Self-harm methodd    
 Violent method 0.86 (0.71–1.04) 1.05 (0.87–1.27) .06 
  Firearms 0.86 (0.52–1.43) 1.21 (0.85–1.70) .21 
  Other violent methods 0.76 (0.62–0.94) 0.86 (0.69–1.08) .22 
 Nonviolent method 1.00 1.00 N/A 
  Poisoning 1.00 1.00 N/A 
  Cutting 0.61 (0.55–0.68) 0.62 (0.56–0.69) .57 
 Other 0.56 (0.48–0.64) 0.61 (0.52–0.72) .17 
  Other 0.50 (0.44–0.58) 0.55 (0.47–0.65) .15 
CharacteristicAdolescents Adjusteda HR (95% CI)Young Adults Adjusteda HR (95% CI)Interaction P
Sex    
 Male 1.00 1.00 N/A 
 Female 1.44 (1.32–1.57) 1.23 (1.13–1.34) .001 
Race and/or ethnicity    
 White, non-Hispanic 1.00 1.00 N/A 
 African American, non-Hispanic 0.74 (0.66–0.82) 0.74 (0.66–0.83) .92 
 Hispanic 0.95 (0.85–1.07) 0.84 (0.73–0.98) .02 
 American Indian or Alaskan native 1.24 (1.08–1.44) 1.08 (0.90–1.31) .17 
 Otherb 0.91 (0.70–1.17) 0.99 (0.78–1.26) .78 
Recent clinical diagnosesc    
 ADHD 1.05 (0.94–1.18) 1.08 (0.91–1.27) .14 
 Disruptive behavior disorders 1.08 (0.99–1.19) 1.27 (1.10–1.46) .005 
 Depressive disorders 1.03 (0.95–1.11) 1.12 (1.04–1.22) .19 
 Bipolar disorders 1.24 (1.12– 1.38) 1.11 (1.00–1.23) .53 
 Anxiety disorders 1.18 (1.07–1.31) 1.30 (1.18–1.43) .10 
 Schizophrenia and related psychoses 0.95 (0.81–1.11) 1.26 (1.14–1.40) .0002 
 Substance use disorders 1.11 (1.01–1.22) 1.16 (1.07–1.26) .31 
 Personality disorders 1.22 (1.03–1.44) 1.40 (1.25–1.56) .09 
 Other mental disorders 0.91 (0.79–1.05) 0.80 (0.66–0.95) .17 
No. clinical mental diagnoses    
 0 1.00 1.00 N/A 
 1 1.04 (0.94–1.15) 1.11 (0.99–1.24) .26 
 2 1.14 (1.02–1.27) 1.33 (1.18–1.50) .01 
 3+ 1.21 (1.07–1.36) 1.55 (1.36–1.75) <.0001 
Recent inpatient mental health carec 1.37 (1.25–1.51) 1.44 (1.31–1.58) .10 
Recent outpatient mental health carec 1.22 (1.13–1.32) 1.26 (1.16–1.37) .03 
Self-harm treatment setting    
 Inpatient 2.16 (1.96–2.38) 1.65 (1.49–1.83) .0002 
 Emergency department 0.69 (0.63–0.77) 0.62 (0.55–0.69) .12 
 Outpatient 1.00 1.00 N/A 
Any recent outpatient carec 1.05 (0.92–1.19) 1.20 (1.04–1.39) .08 
Self-harm methodd    
 Violent method 0.86 (0.71–1.04) 1.05 (0.87–1.27) .06 
  Firearms 0.86 (0.52–1.43) 1.21 (0.85–1.70) .21 
  Other violent methods 0.76 (0.62–0.94) 0.86 (0.69–1.08) .22 
 Nonviolent method 1.00 1.00 N/A 
  Poisoning 1.00 1.00 N/A 
  Cutting 0.61 (0.55–0.68) 0.62 (0.56–0.69) .57 
 Other 0.56 (0.48–0.64) 0.61 (0.52–0.72) .17 
  Other 0.50 (0.44–0.58) 0.55 (0.47–0.65) .15 

N/A, not applicable.

a

Adjusted HRs are from models that control for age, sex, race and/or ethnicity, geographic region, and Medicaid eligibility status.

b

Other race and/or ethnicity includes Asian Americans, Native Hawaiians or other Pacific Islanders, and >1 race.

c

During 180-day period before index self-harm visit.

d

Self-harm methods were measured as (1) violent, nonviolent, and other, with nonviolent methods as the reference group and as (2) firearms, other violent methods, poisoning, cutting, and other, with poisoning as the reference group.

The 1-year suicide standardized mortality rate ratio (SMR) for the study cohort was 26.7 (95% confidence interval [CI]: 19.9–35.1) compared with the matched age, sex, or race and/or ethnicity in the US general population (Table 4). The corresponding suicide SMR was significantly higher for adolescents (46.0, 95% CI: 29.9–67.9) than for young adults (19.2, 95% CI: 12.7–28.0). The cumulative probability of suicide was similar for the 2 age groups during the first 111 days, after which the risk for young adults exceeded the risk for adolescents (Fig 2).

TABLE 4

All Causes of Death, Suicide, and Accidental Deaths in a Cohort of Adolescent and Young Adult Medicaid Patients During the First Year After a Deliberate Self-Harm Event

Demographic Groups and Cause of DeathNo. PatientsPerson-y of Follow-upObserved Deaths, NCrude Mortality Rate per 100 000 Person-yExpected Deaths, NSMR (95% CI)
All causes of death       
 Total sample 32 356 29 400 110 374.2 15.9 6.9 (5.7–8.3) 
  Adolescentsa 17 407 15 836 35 221.0 8.5 4.1 (2.9–5.7) 
  Young adultsa 14 949 13 564 75 552.9 7.3 10.3 (8.1–12.8) 
Suicide       
 Total sample 32 356 29 400 48 163.3 1.8 26.7 (19.9–35.1) 
  Adolescentsa 17 407 15 836 23 145.2 0.5 46.0 (29.9–67.9) 
  Young adultsa 14 949 13 564 25 184.3 1.3 19.2 (12.7–28.0) 
Accidental deaths       
 Total sample 32 356 29 400 24 81.6 7.3 3.3 (2.2–4.8) 
  Adolescentsa 17 407 15 836 44.2 3.9 1.8 (0.8–3.6) 
  Young adultsa 14 949 13 564 17 125.3 3.4 5.0 (3.0–7.8) 
Demographic Groups and Cause of DeathNo. PatientsPerson-y of Follow-upObserved Deaths, NCrude Mortality Rate per 100 000 Person-yExpected Deaths, NSMR (95% CI)
All causes of death       
 Total sample 32 356 29 400 110 374.2 15.9 6.9 (5.7–8.3) 
  Adolescentsa 17 407 15 836 35 221.0 8.5 4.1 (2.9–5.7) 
  Young adultsa 14 949 13 564 75 552.9 7.3 10.3 (8.1–12.8) 
Suicide       
 Total sample 32 356 29 400 48 163.3 1.8 26.7 (19.9–35.1) 
  Adolescentsa 17 407 15 836 23 145.2 0.5 46.0 (29.9–67.9) 
  Young adultsa 14 949 13 564 25 184.3 1.3 19.2 (12.7–28.0) 
Accidental deaths       
 Total sample 32 356 29 400 24 81.6 7.3 3.3 (2.2–4.8) 
  Adolescentsa 17 407 15 836 44.2 3.9 1.8 (0.8–3.6) 
  Young adultsa 14 949 13 564 17 125.3 3.4 5.0 (3.0–7.8) 

Age, sex, race and/or ethnicity matched from CDC WONDER data. CDC, Centers for Disease Control and Prevention; WONDER, Wide-ranging Online Data for Epidemiologic Research.

a

Adolescents were defined as 12–17 years of age and young adults were defined as 18–24 years of age.

FIGURE 2

Cumulative probability of suicide during the 365 days after a self-harm event of adolescents and young adults. Log-rank test χ2 = 7.29, P = .007.

FIGURE 2

Cumulative probability of suicide during the 365 days after a self-harm event of adolescents and young adults. Log-rank test χ2 = 7.29, P = .007.

Close modal

Unadjusted hazards of suicide after nonfatal self-harm were significantly higher for male subjects than female subjects, non-Hispanic white than African American patients, and patients whose initial self-harm involved violent rather than nonviolent methods (Table 5). After controlling for age and sex, the odds of suicide were more than 5 times higher for American Indian and Alaskan native self-harm patients than for white non-Hispanic self-harm patients.

TABLE 5

Suicide Rates in a Cohort of Adolescent and Young Adult Medicaid Patients During the First Year After a Deliberate Self-Harm Event

GroupNo. Patients Person-y at RiskSuicides, NUnadjusted Suicide Rate (per 100 000 Person-y)HR of Suicide (95% CI)Adjusted HR of Suicide (95% CI)a
Total 32 356 29 400 48 163.3 N/A N/A 
Age, y       
 12–17 17 407 15 836 23 145.2 1.00 1.00 
 18–24 14 949 13 564 25 184.3 1.27 (0.72–2.23) 1.03 (0.56–1.89) 
Sex       
 Male 10 492 9447 32 338.8 1.00 1.00 
 Female 21 864 19 953 16 80.2 0.24 (0.13–0.43) 0.24 (0.13–0.44) 
Race and/or ethnicity       
 White, non-Hispanic 19 832 17 986 31 172.4 1.00 1.00 
 African American, non-Hispanic 5396 4892 40.9 0.24 (0.06–0.99) 0.26 (0.06–1.10) 
 Hispanic 4169 3825 52.3 0.31 (0.07–1.28) 0.51 (0.11–2.26) 
 American Indian or Alaska Native 1636 1492 12 804.4 4.69 (2.41–9.13) 5.60 (2.73–11.52) 
 Otherb 813 759 0.0 0.00 (0.00–NA) 0.00 (0.00–NA) 
Recent clinical diagnosesc       
 ADHD or disruptive behavior disorders 6156 5551 10 180.2 1.12 (0.56–2.26) 0.92 (0.44–1.91) 
 Mood disorders 17 131 15 487 22 142.1 0.75 (0.43–1.33) 0.73 (0.40–1.31) 
 Anxiety disorders 4967 4426 158.2 0.95 (0.43–2.12) 1.03 (0.46–2.33) 
 Schizophrenia and related psychoses 3248 2919 308.3 2.08 (1.01–4.29) 1.99 (0.91–4.32) 
 Substance use disorders 7546 6738 14 207.8 1.37 (0.73–2.55) 1.07 (0.57–2.03) 
 Other mental disorders 2338 2160 0.0 0.00 (0.00–NA) 0.00 (0.00–NA) 
No. clinical mental diagnoses       
 0 8411 7725 14 181.2 1.00 1.00 
 1 12 240 11 171 14 125.3 0.69 (0.33–1.44) 0.66 (0.31–1.41) 
 2 7154 6446 14 217.2 1.18 (0.57–2.48) 1.06 (0.50–2.27) 
 3+ 4551 4057 147.9 0.80 (0.31–2.08) 0.65 (0.24–1.74) 
Recent inpatient mental health carec 5458 4967 12 241.6 1.64 (0.85–3.15) 1.58 (0.80–3.10) 
Recent outpatient mental health carec 15 525 13 990 27 193.0 1.40 (0.79–2.48) 1.08 (0.59–1.98) 
Self-harm treatment setting       
 Inpatient 7773 6882 16 232.5 1.22 (0.59–2.54) 1.31 (0.63–2.75) 
 Emergency department 15 919 14 662 17 115.9 0.62 (0.30–1.28) 0.67 (0.32–1.41) 
 Outpatient 7674 6902 13 188.4 1.00 1.00 
Any recent outpatient care 28 945 26 284 44 167.4 1.30 (0.47–3.61) 1.23 (0.44–3.49) 
Deliberate self-harm methodd       
 Violent method 1422 1247 21 1684.4 18.04(9.92–32.80) 13.55 (7.17–25.63) 
  Firearms 277 242 3303.3 35.73 (15.42–82.79) 33.45 (13.31–84.06) 
  Other violent methods 1145 1005 13 1294.1 13.98 (6.79–28.79) 9.73 (4.51–20.96) 
 Nonviolent method 26 341 23 941 22 91.9 1.00 1.00 
  Poisoning 20 519 18 717 17 90.8 1.00 1.00 
  Cutting 5822 5224 95.7 1.04 (0.39–2.83) 0.92 (0.34–2.51) 
 Other 3803 3469 57.6 0.63 (0.15–2.67) 0.53 (0.12–2.28) 
  Other 3803 3469 57.6 0.63 (0.15–2.75) 0.53 (0.12–2.31) 
GroupNo. Patients Person-y at RiskSuicides, NUnadjusted Suicide Rate (per 100 000 Person-y)HR of Suicide (95% CI)Adjusted HR of Suicide (95% CI)a
Total 32 356 29 400 48 163.3 N/A N/A 
Age, y       
 12–17 17 407 15 836 23 145.2 1.00 1.00 
 18–24 14 949 13 564 25 184.3 1.27 (0.72–2.23) 1.03 (0.56–1.89) 
Sex       
 Male 10 492 9447 32 338.8 1.00 1.00 
 Female 21 864 19 953 16 80.2 0.24 (0.13–0.43) 0.24 (0.13–0.44) 
Race and/or ethnicity       
 White, non-Hispanic 19 832 17 986 31 172.4 1.00 1.00 
 African American, non-Hispanic 5396 4892 40.9 0.24 (0.06–0.99) 0.26 (0.06–1.10) 
 Hispanic 4169 3825 52.3 0.31 (0.07–1.28) 0.51 (0.11–2.26) 
 American Indian or Alaska Native 1636 1492 12 804.4 4.69 (2.41–9.13) 5.60 (2.73–11.52) 
 Otherb 813 759 0.0 0.00 (0.00–NA) 0.00 (0.00–NA) 
Recent clinical diagnosesc       
 ADHD or disruptive behavior disorders 6156 5551 10 180.2 1.12 (0.56–2.26) 0.92 (0.44–1.91) 
 Mood disorders 17 131 15 487 22 142.1 0.75 (0.43–1.33) 0.73 (0.40–1.31) 
 Anxiety disorders 4967 4426 158.2 0.95 (0.43–2.12) 1.03 (0.46–2.33) 
 Schizophrenia and related psychoses 3248 2919 308.3 2.08 (1.01–4.29) 1.99 (0.91–4.32) 
 Substance use disorders 7546 6738 14 207.8 1.37 (0.73–2.55) 1.07 (0.57–2.03) 
 Other mental disorders 2338 2160 0.0 0.00 (0.00–NA) 0.00 (0.00–NA) 
No. clinical mental diagnoses       
 0 8411 7725 14 181.2 1.00 1.00 
 1 12 240 11 171 14 125.3 0.69 (0.33–1.44) 0.66 (0.31–1.41) 
 2 7154 6446 14 217.2 1.18 (0.57–2.48) 1.06 (0.50–2.27) 
 3+ 4551 4057 147.9 0.80 (0.31–2.08) 0.65 (0.24–1.74) 
Recent inpatient mental health carec 5458 4967 12 241.6 1.64 (0.85–3.15) 1.58 (0.80–3.10) 
Recent outpatient mental health carec 15 525 13 990 27 193.0 1.40 (0.79–2.48) 1.08 (0.59–1.98) 
Self-harm treatment setting       
 Inpatient 7773 6882 16 232.5 1.22 (0.59–2.54) 1.31 (0.63–2.75) 
 Emergency department 15 919 14 662 17 115.9 0.62 (0.30–1.28) 0.67 (0.32–1.41) 
 Outpatient 7674 6902 13 188.4 1.00 1.00 
Any recent outpatient care 28 945 26 284 44 167.4 1.30 (0.47–3.61) 1.23 (0.44–3.49) 
Deliberate self-harm methodd       
 Violent method 1422 1247 21 1684.4 18.04(9.92–32.80) 13.55 (7.17–25.63) 
  Firearms 277 242 3303.3 35.73 (15.42–82.79) 33.45 (13.31–84.06) 
  Other violent methods 1145 1005 13 1294.1 13.98 (6.79–28.79) 9.73 (4.51–20.96) 
 Nonviolent method 26 341 23 941 22 91.9 1.00 1.00 
  Poisoning 20 519 18 717 17 90.8 1.00 1.00 
  Cutting 5822 5224 95.7 1.04 (0.39–2.83) 0.92 (0.34–2.51) 
 Other 3803 3469 57.6 0.63 (0.15–2.67) 0.53 (0.12–2.28) 
  Other 3803 3469 57.6 0.63 (0.15–2.75) 0.53 (0.12–2.31) 

N/A, not applicable.

a

Adjusted HRs are from models that control for age, sex, race and/or ethnicity, geographic region, and Medicaid eligibility status.

b

Other race and/or ethnicity includes Asian Americans, Native Hawaiians or other Pacific Islanders, and >1 race.

c

During 180-day period before index self-harm visit.

d

Self-harm methods were measured as (1) violent, nonviolent, and other, with nonviolent methods as the reference group and as (2) firearms, other violent methods, poisoning, cutting, and other, with poisoning as the reference group.

The adjusted hazards of suicide after self-harm events with violent methods were significantly larger for adolescents (28.18, 95% CI: 9.98–80.36) than for young adults (7.44, 95% CI: 2.90–19.08) (interaction P value = .04). In a post hoc analysis, American Indian and Alaskan native self-harm patients were significantly more likely than their white non-Hispanic counterparts to have used violent methods during their initial self-harm event (7.36% vs 3.86%, P < .0001). Male self-harm patients were also more likely than female self-harm patients to use violent methods (7.88% vs 5.32%, P < .0001).

After self-harm, the 1-year SMR for all-cause mortality was significantly higher for young adults (10.3, 95% CI: 8.1–12.8) than for adolescents (4.1, 95% CI: 2.9–5.7) (Table 4). The standardized risk of accidental death was significantly elevated in the combined self-harm cohort in relation to matched controls (3.3, 95% CI: 2.2–4.8) and among the young adult cohort (5.0, 95% CI: 3.0–7.8) but not among the adolescent cohort (1.8, 95% CI: 0.8–3.6).

After nonfatal self-harm, adolescents and young adults in the Medicaid program were at 26.7 times higher risk of suicide than that of the demographically matched US general population. The standardized mortality rate ratio of suicide after self-harm was significantly higher for adolescents than young adults. Suicide risk was especially prominent for male subjects, individuals who were American Indians or Alaskan natives, and those whose initial self-harm involved violent methods, such as firearms or hanging. The link between violent initial self-harm method and subsequent suicide was stronger for adolescents than young adults. In the year after self-harm, young adults, but not adolescents, were also at significantly increased risk of dying of accidents.8 

Consistent with past research, nonfatal self-harm was strongly associated with suicide during the first follow-up year.7,8 In a UK self-harm cohort, suicide risk was 35 times higher than the population risk for male subjects and 75 times higher for female subjects,6 whereas in a Swedish self-harm cohort the corresponding suicide risks were 50.2 times higher for male subjects and 7.5 times higher for female subjects.7 One reason that our estimates of relative suicide risk tend to be lower than these estimates may be because our results included self-harm presenting to all settings, whereas the United Kingdom and Swedish studies involved only patients treated in hospitals who were presumably at higher risk.

Adolescents and young adults had roughly similar rates of suicide after self-harm. The diagnostic composition of the 2 age groups, including larger proportions of ADHD and disruptive behavior disorders among adolescents and substance use and personality disorders among young adults, likely reflects differences in ages of onset and clinical diagnostic practices. Because the general population risk of suicide is lower in adolescents than young adults, however, the standardized risk of suicide after self-harm was significantly higher for adolescents than young adults. It is possible that neurodevelopmental vulnerabilities during adolescence linked to the onset of mood and substance use disorders, risk-taking behaviors, or heightened susceptibility to negative social cues contribute to the relatively high suicide risk during adolescence following self-harm.32,33 

Self-harm presented differently in adolescents and young adults. Although depression and anxiety diagnoses were common in both age groups, adolescents with self-harm were far more likely to have been recently diagnosed with ADHD and other disruptive behaviors, whereas young adults more commonly had substance use and personality disorder diagnoses. Similar age-related patterns have been reported among young people who received diagnostic assessments after suicide attempts.34,37 

The risk of repeated self-harm during the first follow-up year was over 100 times greater than the risk of suicide. High recurrence of self-harm underscores persistence of self-injurious behaviors in this age group. Consistent with previous research,38 several clinical diagnoses including personality, anxiety, mood, substance use, schizophrenia, and disruptive behavior disorders were related to an elevated risk of repeated self-harm. The wide distribution of risk across common clinical psychiatric diagnoses complicates prediction of repeated attempts. Also in line with previous research,8 patients admitted for inpatient care were significantly more likely than outpatients to have repeated self-harm.

Suicide risk after self-harm was ∼4 times greater for male subjects than female subjects. Some potential explanations for the preponderance of suicide among male subjects include sex-related differences in mental health treatment–seeking behavior,39 self-harm methods,40 and pubertal development.41 Because the risk for repeated self-harm was greater for female subjects than male subjects, higher lethality of male than female self-harm events likely contributes to the preponderance of suicides by male subjects after self-harm.

Risks of suicide after self-harm were ∼5 times higher for white than African American young people, suggesting that self-harm poses a particular threat to white adolescents and young adults. By contrast, risk of repeat self-harm was only modestly higher for white than African American individuals. In nationally representative US samples, no significant differences have been found in the lifetime prevalence of suicide attempts of African American and white young adults.42,43 However, as compared with their African American counterparts, white young adults may have a significantly higher prevalence of suicidal ideation43 as well as mood, anxiety, and substance use disorders.44 Greater exposure to these and other suicide risk factors may contribute to the relatively high suicide risk of white young people after self-harm.

Suicide risk after self-harm was particularly elevated for American Indian and Alaska Native young people, a group with increased suicide rates.45 These results underscore the need for suicide prevention initiatives in American Indian and Alaska Native communities. In 1 recent report, a multitiered suicide prevention program among the Apache of Arizona, which included efforts to increase identification, coping skills, and resilience of at-risk young people, coincided with a 23% decrease in suicide among 15- to 24-year-olds.46 

In accordance with previous research with adults, violent self-harm methods posed a high risk for subsequent suicide.8,27,47,48 Acquiring the capability to use more violent or lethal methods, although less common than lower lethality methods, may increase suicide risk by weakening a fear of death.49 Suicide risk was especially great after initial nonfatal self-harm involving firearms. For high-risk young people with access to firearms, distributing trigger locks and urging family members to store firearms away from the patient’s home50 can be a lifesaving precautionary measure. The association between violent methods and subsequent suicide was significantly stronger for adolescents than young adults, although this interaction was based on a small number of suicide deaths and therefore requires replication.

This study has several limitations. First, claims records do not distinguish self-harm injuries with suicidal from nonsuicidal intent.51 Variation in suicidal intent may mediate risks across clinical groups. For example, high suicidal intent might partially mediate the association between high lethality self-harm methods and suicide risk, whereas persistently low or no intent (nonsuicidal self-injury) might mediate the association between personality disorders and repeated self-harm. Second, we have no means of validating mental disorder diagnoses in Medicaid claims records. Third, information was not available concerning several factors thought to increase suicide risk, such as hopelessness, problem-solving deficits, stressful or traumatic life events, and access to lethal means. Because community mental treatment may be more intensive and effective after severe or violent self-harm events, it may have reduced risks of suicide and repeated self-harm events. Fourth, misdiagnosis and perceptions of stigma may have introduced errors in coding self-harm, and low autopsy rates may have resulted in misclassification of cause of death.52 Fifth, claims records do not capture self-harm that does not result in medical care. Sixth, the data reflect suicide mortality patterns in 2001–2007, which may have changed in recent years. Finally, although there are concerns over the validity53 and completeness54 of E-codes to measure deliberate self-harm, a high concordance exists between self-harm E-codes and medical record documentation of intentional injury with suicidal intent.55 

Adolescents and young adults who survive self-harm are at high risk for repeated self-harm and suicide over the following year. The risk of suicide was especially marked after nonfatal self-harm events that involved violent methods. Clinical priority should be given to ensuring the safety of young people after self-harm, which may include treating underlying psychiatric disorders, restricting access to lethal means, fortifying psychosocial supports, and close monitoring for emerging suicidal symptoms.

     
  • ADHD

    attention-deficit/hyperactivity disorder

  •  
  • CI

    confidence interval

  •  
  • E-code

    external cause of injury code

  •  
  • HR

    hazard ratio

  •  
  • SMR

    standardized mortality rate ratio

Dr Olfson conceptualized and designed the study, drafted the initial manuscript, interpreted the data, and revised the manuscript; Drs Blanco and Wall designed the study, interpreted the data, and reviewed and revised the manuscript; Dr Wang and Ms Liu conducted the initial analysis and reviewed and revised the manuscript; Drs Bridge and Crystal interpreted the data and reviewed and revised the manuscript; Dr. Wang had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and or preparation or approval of the manuscript.

FUNDING: Supported by a grant from the Agency for Healthcare Research and Quality (U19 HS021112).

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Competing Interests

POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose. The opinions expressed in this article are those of the authors and do not reflect the views of the National Institutes of Health, the Department of Health and Human Services, or the United States government.

FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.

Supplementary data