Effects of a Hospital-Based Violence Intervention Program on Community Violence in Boston, Massachusetts

BACKGROUND: Hospital-based violence intervention programs (HVIPs) are widespread, but their effectiveness for violence prevention is unclear. OBJECTIVE: To determine the effects of Boston Medical Center's HVIP on future violence outcomes among violently injured young adults. DESIGN: Target trial emulation using observational data. SETTING: Boston, Massachusetts. PARTICIPANTS: Young adults aged 16 to 34 years who survived a shooting or stabbing. INTERVENTION: Target trials of 2 treatment strategies using the same eligibility criteria, time zero, and control group were emulated: 1) any treatment: engaging with the HVIP within 1 month of injury and 2) sustained treatment: initiating within 1 month and engaging more than 4 of the first 8 weeks. MEASUREMENTS: Combined measure of violent reinjury or violence perpetration at 1, 2, and 3 years, using hospital and police data. RESULTS: 1328 patients met criteria; 565 (42.5%) initiated within 1 month. Of these, 58 (10.2%) sustained engagement. In the any-treatment analysis, estimated cumulative incidence was roughly equal between the treatment and control strategies at 1, 2, and 3 years. In the sustained engagement analysis, treatment was associated with considerably lower cumulative incidence (4.5% [95% CI, 1.1% to 9.3%] at 1 year; 5.1% [CI, 1.1% to 9.3%] at 2 years; 6.4% [CI, 1.4% to 12.9%] at 3 years) versus the control strategy (8.7% [CI, 6.6% to 10.0%] at 1 year; 12.3% [CI, 10.2% to 14.5%] at 2 years; 14.3% [CI, 11.8% to 16.6%] at 3 years), with corresponding risk reductions of 47.6% (CI, -19.8% to 86.7%), 58.5% (CI, 21.6% to 91.2%), and 55.3% (CI, 4.9% to 90.2%). Confidence intervals were wide. LIMITATION: Despite our target trial emulation approach, results could be confounded by unmeasured factors associated with program engagement. CONCLUSION: Although HVIPs can improve long-term violence outcomes, these effects seem to require intensive participant engagement. PRIMARY FUNDING SOURCE: Fund for a Safer Future.