Self-harm in youth : predicting mental illness, social marginalisation and suicide

The aims of this thesis were to study self-harm in young people and to evaluate the risks of adverse outcomes through short- and long-term follow-up. The primary focus was on the risk of suicide, and also on the risk of mental illness and labour market marginalisation in adult life. There was further the intention to explore risk-increasing factors that might signal an elevated risk of an adverse outcome, and thereby help to identify the young people most at risk of suicide.

Methods: Linked national registers were used to identify self-harm events registered in the Swedish National Patient Register (NPR) in studies 1–4. In Study 1, all self-harm events conducted by those aged >10 in 1990-99 were included. In Study 3, all self-harm events conducted by those aged 18-24 in 1990-2003 were included. Both of these studies also used unexposed individuals from the general population, matched by age and sex. In Study 2, all Swedish residents aged 16-30 in 1994 were included, and exposure was defined as a suicide attempt in the NPR in 1992-1994. In Study 4, self-harm events among 10-24 year-olds in 2000-2009 were included. In Study 5, a clinical multicentre cohort of patients who had attempted suicide was examined. Data on previous self-harm, age at self-harm, method of self-harm, mental disorders before or at self-harm, parental educational level, family history of suicide, and the impulsivity of the suicide attempt were collected to explore factors that might be of importance to self-harm and affect the risk of adverse outcomes. The outcomes studied were death by suicide, psychiatric hospitalisation, psychotropic medication and sickness absence, disability pension and unemployment, and fatal or non-fatal suicide attempt within six months. Proportions of outcomes were calculated, and associations between exposures and outcomes were investigated by the use of logistic regression and Cox proportional hazard models, with adjustment for relevant confounders.

Results: Suicide within one year and in long-term follow-up were highly elevated after self-harm compared to those not exposed to self-harm (Study 1, 3). The risk of suicide was lower after self-harm in 10-19 year-olds compared to those who had self-harmed in older age groups (Study 1), but clearly elevated compared to those unexposed to self-harm. After adjustment for relevant confounders, such as mental disorders, the Hazard Ratio (HR) for suicide in longterm follow-up was 16.4 (12.9–20.9) after self-harm among 18-24 year-olds compared to unexposed (Study 3).

The presence of a mental disorder, especially a psychotic disorder, was an indicator of an elevated risk of suicide among those who had self-harmed (Study 3). Among self-harm events that required medical inpatient care in 10-17 year-olds and in 18-24 year-old women, the use of a violent method signalled an elevated risk of suicide, as did cutting that required medical inpatient care in 18-24 year-old women compared to poisoning (Study 4). The risk of a fatal or-non-fatal repetition within six months was equally high among those who had made an impulsive suicide attempt (ISA) as those with a non-impulsive attempt (Study 4). ISAs were common among young adults and resulted in injuries that were at least as medically severe as more planned suicide attempts.

Out of those who were exposed to self-harm, 20.3% had a psychiatric hospitalisation of more than 5 years after the index event (Study 3). Psychotropic medication had been prescribed to and purchased by 51.1% >5 years after the index event; the most commonly prescribed medications were antidepressants, benzodiazepines and hypnotics (Study 3). After a suicide attempt in youth, the adjusted HR for long-term unemployment was 1.58 (95% CI 1.52 – 1.64), for sickness absence ≥ 90 days 2.16 (2.08 – 2.24), and for disability pension 4.57 (4.34 – 4.81), compared to those unexposed to a suicide attempt (Study 2). After stratification for previous psychiatric inpatient care, the effect of a suicide attempt was still significant for sickness absence and disability pension in both groups, but not for unemployment (Study 2).

Conclusions: Self-harm at a young age highly elevates the risk of suicide, in both the short and long perspective. Assessment of the suicide risk is challenging and highly important. Some of the indicators of a particularly elevated risk of suicide are a mental disorder present at the time of self-harm, especially a psychotic disorder, and a violent method used to self-harm. Suicide attempts that occur without prior planning can result in medically severe injuries and imply a high risk of fatal-or-non-fatal repetition. Upon assessment of young individuals after selfharm, the elevated risk of future mental illness and labour market marginalisation should be kept in mind. The prevention of those adverse outcomes should be a focus in the efforts to help these young individuals in the transition into adult life.