Chronic somatic comorbidity and excess mortality due to natural causes in persons with schizophrenia or bipolar affective disorder

Background

Suicide and death by accidents in persons with schizophrenia and bipolar disorder are common, but excess mortality from natural death accounts for even more years of life lost. The impact of somatic comorbidity, however, often is not duly considered in analyses and explanations of excess mortality in patients with psychotic disorders.

Objective/Methods

This study investigates and evaluates the impact of 19 severe chronic diseases on excess mortality due to diseases and medical conditions (natural death) in individuals with psychotic disorders compared with the general population using a population-based cohort study in Denmark. Incidence/mortality rate ratios of admission/mortality were calculated using survival analysis.

Results

Cohort members with psychotic disorders had higher incidence rates of hospital contacts for almost all of the 19 disorders than the general population. The mortality rate ratio (MRR) of natural death was 7.10 (95% CI 6.45, 7.81) for schizophrenic men, decreasing to 4.64 (95% CI 4.21, 5.10) after adjustment for the somatic disorders. The same pattern existed in women and in both genders with bipolar disorder. Highest MRRs were observed for psychotic patients without hospital admissions with the investigated somatic disorders.

Conclusion

Chronic somatic diseases accounted for half of the excess mortality in patients with schizophrenia or bipolar disorder. Chronic disorders investigated in this paper seem to be under-treated or under-detected among such patients.