Suicide risk among hospitalized versus discharged deliberate self-harm patients: Generalized random forest analysis using a large claims data set

Introduction: Suicide rates are extremely high among emergency department patients seen for deliberate self-harm. Inpatient hospitalization is often recommended for these patients, but evi- dence on the suicide prevention impacts of hospitalization is scarce. Confounding by indication and challenges to implementing randomized designs are barriers to advances in this field. Methods: Investigators used 2009−2012 statewide data on 57,312 self-harm emergency department patients from California, linked to mortality records. Naive 12-month and 30-day suicide risks were estimated among patients who were hospitalized versus those who were discharged. Then, generalized random forest methods were applied to estimate the average treatment impacts of hospitalization on suicide, conditioning on observable covariates. Associations were calculated separately for sex- and age-specific subgroups. Analyses were conducted in February 2019−August 2021. Results: In naive analyses, suicide risk was significantly higher in hospitalized than in discharged patients in each subgroup. In 12-month models accounting for the observed covariates through generalized random forest methods, hospitalized male patients had 5.4 more suicides per 1,000 patients (95% CI=3.0, 7.8), hospitalized patients aged 10−29 years had 2.4 more suicides per 1,000 (95% CI=1.1, 3.6), and those aged ≥50 years had 5.8 more suicides per 1,000 (95% CI=0.5, 11.2) than corresponding discharged patients. Hospitalization was not significantly associated with sui- cide among female patients or patients aged 30−49 years in generalized random forest analyses. Patterns were similar in 30-day generalized random forest models. Conclusions: Emergency department personnel intend to hospitalize self-harm patients with high suicide risk; this study suggests that this goal is largely realized. Analyses that control for confound- ing by observable covariates did not find clear evidence that hospitalization reduces suicide risk and could not rule out the possibility of iatrogenic effects.