Psychotic depression and deaths due to suicide

Background: The purpose of this study was to establish the risk of suicide associated with incident psychotic depression (PD) compared to incident non-psychotic severe depression (NPD). Methods: This cohort study used routine data from nationwide health registers in Finland. Eligible participants were aged 18-59 years at the index diagnosis. Causes of death were defined by the International Classification of Diseases, 10th revision codes. The follow-up time was up to five years. Adjusted Cox regression models were used to analyse risk of death by method of suicide. Results: We included 17,331 individuals with incident PD and 85,989 individuals with incident NPD. Most of the deaths due to suicides occurred within the first two years after the index diagnosis. Compared to NPD, PD was associated with an overall two-fold increased risk of suicide (adjusted hazard ratio, (aHR) 2.19, 95 % confidence interval (CI) 1.95, 2.46), after adjusting for psychiatric comorbidities. In PD, the highest relative risks were for impact-related suicides (aHR 3.03, 95%CI 2.23, 4.13) and for suffocation-related suicides (aHR 2.72, 95%CI 2.23, 3.30), whereas the lowest relative risk was for intentional poisonings (aHR 1.66, 95%CI 1.37, 2.02). Limitations: Information on all potential confounders is not available in studies using routine data. Conclusions: Psychotic symptoms doubled the risk of suicides over and above of the risk that was associated with severe depression, after controlling for comorbid psychiatric disorders. The severity of suicidal ideation may be higher in PD than in NPD, which then leads to more lethal methods of self-harm.