The relationship between alcohol and cannabis use with nonsuicidal self-injury among adolescent inpatients: Examining the 90 days prior to psychiatric hospitalization

•Suicide planning and suicidal ideation increased the odds of engaging in same day NSSI.•Neither cannabis nor alcohol use independently predicted the odds of same day NSSI.•The co-occurrence of alcohol and cannabis use increased the odds of same day NSSI. This study examined the trajectories of alcohol use, cannabis use, suicide planning (SP), and nonsuicidal self-injury (NSSI) prior to hospitalization and examined the role of alcohol and cannabis use, independently and jointly, in predicting NSSI on a daily level and over time. Participants included 71 adolescents hospitalized for suicide risk (75% female; 25% male; Mage = 15.79). All participants drank alcohol at least once in the prior 90-days. We conducted mixed effect models to assess the trajectories of alcohol use, cannabis use, and NSSI over the 90-days prior hospitalization. To test the effect of SP, alcohol use, and cannabis use on NSSI, we conducted logistic random effect models, while controlling for demographics. SP (OR = 4.47, p