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

Abstract

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.

Keywords:

• Self-harm
• suicide
• method
• case fatality

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 This term encompasses both suicide attempts and non-suicidal self-harm. It is used because hospital coding systems identify self-harm cases but do not differentiate attempts from non-suicidal self-harm.

Additional information

Funding

Barber and Miller’s time on this study was supported by an award from the National Collaborative on Gun Violence Research (ncgvr.org). The views expressed are the authors’ and do not necessarily reflect the view of the NCGVR.