A cohort study of initial self-harm events: method-specific case fatality of index events, predictors of fatal and nonfatal repetition, and frequency of method-switching.

Most studies evaluating self-harm repetition risk factors are from Asia and Europe, use cohorts of people who self-injure without differentiating incident and prevalent self-harm episodes, and do not stratify by suicide method. The current study uses an incident user design to (a) examine case fatality at index self-harm events and at each repeat event, by method, (b) describe method-switching, and (c) identify factors associated with repetition of self-harm among those who survive their index hospitalization. Specifically, this study reports psychiatric history and method-specific case fatality for the initial self-harm event among Utah residents with an index event in 2014 or 2015 and who have no history of prior self-harm in hospital records. For survivors of the index self-harm episode, we use Accelerated Failure Time models to identify risk factors for nonfatal repetition and separately for suicide. Key findings: 10,521 Utah residents with no 3-year self-harm hospital history experienced a 2014 or 2015 index event. Of the 9.5% with index deaths, 53.6% used firearms. Of the 90.5% who survived, 63.1% used drugs. Among the index nonfatal cases, over an average 1-year follow-up, 11.7% experienced a nonfatal repetition and 0.8% died by suicide. Most subsequent nonfatal repetitions (59.7%) and suicides (56.8%) had presented with an index drug poisoning; over half (56.8%) of those who died switched methods. For those who subsequently fatally self-harmed, most used poisoning by drugs (33.8%), hanging/strangulation (28.4%), or firearms (24.3%) in the terminal episode. Nonfatal repetition was associated with younger age, index cutting/piercing instruments, and past-year psychiatric and drug abuse diagnoses. Subsequent suicide was associated with male gender, older age, and index gas poisoning and hanging/suffocation. Of the 56 people who survived an index firearm event, none subsequently died by suicide during the study period.