Abstract
OBJECTIVE: To estimate the effect of a handgun purchase waiting period repeal on handgun and firearm suicides in Wisconsin. METHODS: Data for outcome and predictor variables were obtained for the 1999-2020 study period. Synthetic controls were used to assess the impact of Wisconsin's waiting period repeal on mean-centred suicide rates. Placebo tests, difference-in-differences regression and augmented synthetic controls supplemented the synthetic control analyses. RESULTS: Postrepeal suicides were more likely to involve handguns than those in the 5 years immediately preceding the repeal (χ² (1, N=8269) = 49.25, p<0.001). The waiting period repeal resulted in an estimated annual increase of 1.1 handgun suicides per 100 000, or roughly 65 handgun suicide deaths per year. Estimates from difference-in-differences regression and augmented synthetic control analyses indicated similar treatment effects. Relative to the synthetic control, firearm suicides increased 6.5% following the repeal. CONCLUSION: The waiting period repeal in Wisconsin was associated with increases in both handgun and firearm suicides. The findings suggest that waiting periods may be effective means restriction policies to reduce suicide. Additionally, the synthetic control's ability to closely approximate preintervention handgun suicide trends despite a limited donor pool has implications for future policy analyses.