METHODS Study Design and Setting

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METHODS Study Design and Setting

METHODS Study Design and Setting
METHODS Study Design and Setting

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Data were collected during the Flint Youth Injury study (9 –11), a 2-year prospective cohort study of assault-injured youth (age 14 to 24 years) with any drug use in the past 6 months and a comparison group of non–assault-injured, drug-using youth seeking ED care at a level 1 trauma center in Flint, Michigan. The parent study focused on service needs and utilization among substance (predominantly marijuana) users. Although this potentially limits generalizability, we note that most youth who seek care for assault injuries in this setting are substance users (9). Patients were recruited from December 2009 through September 2011, 24 hours per day on Thursday through Monday and from 5 a.m. to 2 a.m. on Tuesday and Wednesday. Youth who sought care for sexual assault, child abuse, suicidal ide- ation or attempt, or any conditions that preclude con- sent (such as altered mental status) were excluded. In- stitutional review boards at the University of Michigan and Hurley Medical Center approved the study. A Na- tional Institutes of Health (NIH) Certificate of Confiden- tiality (COC) was obtained.

Potential participants were ascertained through electronic patient logs and approached by research as- sistants in waiting or treatment areas. All assault-injured youth, including those who were initially unstable but stabilized with 72 hours of presentation, were ap- proached and screened for study eligibility. In se- quence, the next available age group (14 to 17, 18 to 20, and 21 to 24 years) and sex-matched, non–assault- injured ED entrant was screened for the comparison group. Those providing consent (or assent with paren- tal consent for those younger than age 18 years) pri- vately self-administered the screening survey using a tablet device and received a $1.00 gift for participation. Individuals who self-reported drug use in the past 6 months (98% used marijuana) were considered eligible and consented to the subsequent 2-year longitudinal study. Appendix Figure 1 (available at shows a flow chart of the original study. Remunera- tion was $20 for completion of a subsequent self- administered baseline survey. Follow-up assessments were conducted at 6, 12, 18, and 24 months, and participants were compensated $35, $40, $40, and $50 for each sequential follow-up. Baseline characteristics (9) and 2-year outcomes (5, 10) are reported elsewhere.

Measures The following measures were assessed: The outcome variable was a binary indicator of firearm violence (victimization, perpetration, firearm injury requiring medical care, or firearm death) during the 24- month follow-up period, ascertained through a com- posite of self-report, medical chart review, and vital re- cords databases (see Carter and colleagues [5] for greater detail). Both peer and partner firearm violence was included. Although the dynamics of peer and part- ner violence differ, we justify combining them by noting the large overlap between victims (12, 13) and perpe- trators (14 –16) of peer and partner violence.

Candidate predictor variables were taken from baseline self-report surveys; in addition to age, sex, and reason for ED visit (assault-injured/non–assault-injured), we included 115 survey items. Other variables that were measured but judged unlikely to be assessed ac- curately and truthfully (for example, serious violence perpetration) without an NIH Certificate of Confidenti- ality were not considered. See the Supplement (avail- able at for question wording and response options for all items described below.

1. Violence items (13 items) from the National Lon- gitudinal Study on Adolescent Health (17) captured the frequency of received threats/violence, perpetrated threats, fighting, and carrying a weapon while intoxi- cated in the past 6 months.

2. Partner aggression (13 items) was assessed with Conflict Tactics Scale items (18), which measured the frequency of partner violence victimization in the past 6 months.

3. Nonpartner aggression (13 items) was assessed with questions modified from the Conflict Tactics Scale (18), measuring the frequency of nonpartner violence victimization in the past 6 months.

4. Community violence exposure (5 items) included assessment of the frequency of exposure to violence and neighborhood crime in the past 6 months (19).

5. Mental health (12 items) was measured with the Brief Symptom Inventory checklist (20), which assessed severity of depression and anxiety in the past week.

6. Drug and alcohol efficacy (16 items) assessed confidence in avoiding drug (8 items) or alcohol (8 items) use in various situations (21, 22).

7. Alcohol use (10 items) was assessed with the Al- cohol Use Disorders Identification Test (AUDIT), which measures the frequency of alcohol consumption and alcohol-related consequences in the past 6 months (23, 24).

8. Peer influences (11 items) included items from the Flint Adolescent Study (25) regarding the number of friends providing positive (4 items) and negative (7 items) influences; positive items were reverse coded.

9. Parental behavior (10 items) included items from the Flint Adolescent Study (25) assessing parental sup-

10. Retaliatory attitudes (7 items) included items as- sessing willingness to engage in violent retaliation; higher scores indicate greater willingness (26, 27).

11. Fight self-efficacy (5 items) assessed perceived ability to avoid conflicts (28).