Accidental deaths among persons with schizophrenia: A nationwide population-based cohort study

Abstract

Objectives: Persons with schizophrenia have a shorter life expectancy by 15-20years compared to the background population, but little is known about deaths caused by accidents. We aimed to investigate the rates of accidental death among persons with schizophrenia and compare these rates with those of the background population.

Methods: We conducted a national register-based cohort study of all persons born in Denmark between 1955 and 2011. The cohort included 2,703,307 persons, representing 56,845,085 person years at risk. We compared rates of accidental death between persons with schizophrenia and those without by using Cox regression analysis. The main outcome measure was hazard ratio (HR) for accidental death.

Results: A total of 12,425 accidental deaths were identified, including 371 accidental deaths among persons with schizophrenia. We found an increased HR for both women with schizophrenia (10.47; 95% CI=8.07-13.58) and men with schizophrenia (8.33; 95% CI=7.44-9.33) compared to the background population. After adjusting for substance abuse, we found attenuated HRs for both women (HR=3.22; 95% CI=2.46-4.20) and men (HR=3.23; 95% CI=2.87-3.63).

Conclusions: Schizophrenia is a strong independent risk factor for accidental deaths. Substance abuse seems to constitute a substantial part of the association.

Keywords: Accidental death; Cohort study; Risk factors; Schizophrenia; Substance abuse.