Suicide mortality and use of psychotropic drugs in patients hospitalized due to bipolar disorder: A Finnish nationwide cohort study

Abstract

Background:Knowledge on the comparative effectiveness of pharmacological treatments to prevent suicidemortality in bipolar disorder is still lacking.Methods:We studied the risk of suicide mortality during 1996-2012 among all patients who had been hospi-talized due to bipolar disorder in Finland (n = 18,018; mean follow-up time 7.2 years) using nation-widedatabases. We used a Cox proportional hazards model. Analyses were adjusted for the effects of time sincediagnosis, order of treatments, current use of other treatments, polypharmacy, number of suicidal hospitaliza-tions within 2 year (indicator of inherent risk of relapse), age at index date, sex, and calendar year of index date.In secondary analysis, the first 30 days were omitted from analysis after initiation of a psychopharmacologicaltreatment to control for protopathic bias.Results:In comparison between use and no use among specific agents, only lithium (HR 0.33, 95%CI 0.24-0.47,p<0.0001) and valproic acid (HR 0.61, 95%CI 0.48-0.79, p=0.0002) were associated with a significantly de-creased risk of suicide in bipolar disorder. Lithium showed a 42% lower risk for suicide mortality compared tovalproic acid (HR 0.58, 95% CI 0.39-0.86, p = 0.007). Hypnotics were associated with a significantly (HR 1.52,95%CI 1.22-1.90, p=0.0002) higher risk of suicide.Limitations:Only hospitalized patients were included.Conclusions:Lithium should be considered as treatment of choice for patients with bipolar disorder who are athigh risk for suicide. Hypnotic use among suicidal patients indicates need for close monitoring of these patients.