Total and cause-specific mortality in patients with personality disorders: the association between comorbid severe mental illness and substance use disorders.

PURPOSE To investigate the mortality in both in- and outpatients with personality disorders (PD), and to explore the association between mortality and comorbid substance use disorder (SUD) or severe mental illness (SMI). METHODS All residents admitted to Norwegian in- and outpatient specialist health care services during 2009-2015 with a PD diagnosis were included. Standardized mortality ratios (SMRs) with 95% confidence intervals (CI) were estimated in patients with PD only and in patients with PD and comorbid SMI or SUD. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% CIs in patients with PD and comorbid SMI or SUD compared to patients with PD only. RESULTS Mortality was increased in both in- and outpatients with PD. The overall SMR was 3.8 (95% CI 3.6-4.0). The highest SMR was estimated for unnatural causes of death (11.0, 95% CI 10.0-12.0), but increased also for natural causes of death (2.2, 95% CI 2.0-2.5). Comorbidity was associated with higher SMRs, particularly due to poisoning and suicide. Patients with comorbid PD & SUD had almost four times higher all-cause mortality HR than patients with PD only; young women had the highest HR. CONCLUSION The SMR was high in both in- and outpatients with PD, and particularly high in patients with comorbid PD & SUD. Young female patients with PD & SUD were at highest risk. The higher mortality in patients with PD cannot, however, fully be accounted for by comorbidity.