Population attributable risk of factors associated with the repetition of self-harm behaviour in young people presenting to clinical services: a systematic review and meta-analysis.

The repetition of hospital-treated self-harm by young people is common. However, little work has summarised the modifiable factors associated with this. A thorough understanding of those factors most strongly associated with repetition could guide the development of relevant clinical interventions. We systematically reviewed four databases (EMBASE, Medline, PubMed and PsycINFO) until 15 April 2016 to identify all observational studies of factors for the repetition of self-harm or suicide reattempts (together referred to as 'self-harm behaviour') in young people. We quantified the magnitude of association with odds ratios (OR) and 95% confidence intervals (CIs) and calculated the population attributable risk (PAR) and population preventable fraction (PPF) for modifiable factors to provide an indication of the potential impact in reducing subsequent self-harm behaviour in this population. Seventeen studies were included comprising 10,726 participants. Borderline personality disorder (OR 3.47, 95% CI 1.84-6.53; PAR 42.4%), any personality disorder (OR 2.54, 95% CI 1.71-3.78; PAR 16.3%), and any mood disorder (OR 2.16, 95% CI 1.09-4.29; PAR 42.2%) are important modifiable risk factors. Severity of hopelessness (OR 2.95, 95% CI 1.74-5.01), suicidal ideation (OR 2.01, 95% CI 1.43-2.81), and previous sexual abuse (OR 1.52, 95% CI 1.02-2.28; PAR 12.8%) are also associated with repetition of self-harm. We recommend that clinical services should focus on identifying key modifiable risk factors at the individual patient level, whilst the reduction of exposure to child and adolescent sexual abuse would also be a useful goal for public health interventions.