Suicidal behaviour in three high-risk populations : epidemiological and clinical cohort studies

Abstract

Aims: The subject of this thesis is risk factors for suicidal behaviour in three high-risk populations; bipolar patients, released prisoners and suicide attempters, to provide knowledge for improvement of strategies for preventing suicide. In study I, we investigated factors related to bipolar disorder and the risk for suicidal behaviour. Study II analysed the role of psychiatric risk factors in released prisoners. The objective in study III was to evaluate the ability of the Karolinska Interpersonal Violence Scale (KIVS) to predict repeated suicidal behaviour in a cohort of suicide attempters within six months.

Methods: All three studies are cohort studies by design. Study I is based on 6 068 bipolar patients from the quality register BipoläR followed-up between 2005 and 2012. Studied outcome is suicidal behaviour during follow-up. Studied risk factors include characteristics of the bipolar disorder and psychiatric comorbidity. Study II is based on 26 985 prisoners who were released 38 995 times during 2005–2009. Data for this study comes from population-based registers and studied outcome is completed suicide. Study III is based on a clinical sample of 355 suicide attempters who have been interviewed with the KIVS. Studied outcome is repeated suicidal behaviour within six month.

Results: The most important risk factors for suicidal behaviour in study I were previous suicide attempts (OR = 3.9 for men, 4.2 for women), recent affective episodes (OR = 3.6 for men, 2.8 for women) and recent psychiatric inpatient care (OR = 3.6 for men, OR = 2.7 for women). Risk was also elevated by co-morbidity with personality disorder for women and substance use disorder for men. In study II a total of 127 suicides occurred among the released prisoners. The incidence was 18 times higher compared with non-convicted general population controls. Previous suicide attempt (HR = 2.5), substance use disorder (HR = 2.1), and being born in Sweden versus abroad (HR = 2.1) were independent risk factors for suicide after release. Affective disorders were less prevalent in ex-prisoner suicides compared with suicides in the non-convicted control group. In study III repeated suicidal behaviour was observed in 78 persons (22%) within six months. To have a KIVS total-score of 6 and above was associated with an increased risk of repeated suicidal behaviour (OR = 1.8) and predicted repetition with a sensitivity of 62% and a specificity of 53%.

Conclusions: The principal clinical implications are that 1) a clinician should be observant of the risk of suicidal behaviour in bipolar patients who display depressive features and a more unstable disorder, 2) released prisoners constitute a high risk population for suicide and information about previous suicidal behaviour and substance use disorder is important for the assessment of risk in this population, 3) information about interpersonal violence may enhance the prediction of short-term risk for repeated suicidal behaviour.