BACKGROUND: The risk of self-harm repetition and suicide may be influenced by self-harm method choice. However, there are mixed findings regarding whether there is a discernible pattern in self-harm methods over successive episodes of non-fatal self-harm, and if so, how these may be associated with self-harm repetition and/or suicide.

METHODS: A systematic review of five electronic databases was undertaken until 31 May 2018 to identify cohort studies on patterns of self-harm methods and their association with methods used either at repeat self-harm episodes and/or suicide.

RESULTS: 15 studies were included reporting data on of 127,371 participants. Over an average follow-up period of 2.8 years, one-third (33.3%) switched methods between episodes of self-harm, most commonly from self-injury to self-poisoning. For suicide, almost one-half (42.1%) switched methods over an average follow-up period of 11.2 years.

LIMITATIONS: Studies were characterised by a moderate study quality. Studies tended to group all methods into self-injury and/or self-poisoning with little consideration as to the diverse range of self-harm methods included within these broad categories and the likely differences in potential lethality between these methods. Few investigated the role of alcohol and/or drug dependence and mental illness on self-harm method choice.

CONCLUSIONS: Given the frequency of method switching observed, and the lack of discernible patterns over time, all patients should be routinely assessed for risk and needs irrespective of the method used at the index episode of non-fatal self-harm.