Comorbidities and mortality in persons with schizophrenia: a Swedish national cohort study

Abstract

Objective: Schizophrenia is associated with premature mortality, but the specific causes and pathways are unclear. The authors used outpatient and inpatient data for a national population to examine the association between schizophrenia and mortality and comorbidities.

Method: This was a national cohort study of 6,097,834 Swedish adults, including 8,277 with schizophrenia, followed for 7 years (2003-2009) for mortality and comorbidities diagnosed in any outpatient or inpatient setting nationwide.

Results: On average, men with schizophrenia died 15 years earlier, and women 12 years earlier, than the rest of the population, and this was not accounted for by unnatural deaths. The leading causes were ischemic heart disease and cancer. Despite having twice as many health care system contacts, schizophrenia patients had no increased risk of nonfatal ischemic heart disease or cancer diagnoses, but they had an elevated mortality from ischemic heart disease (adjusted hazard ratio for women, 3.33 [95% CI=2.73-4.05]; for men, 2.20 [95% CI=1.83-2.65]) and cancer (adjusted hazard ratio for women, 1.71 [95% CI=1.38-2.10; for men, 1.44 [95% CI=1.15-1.80]). Among all people who died from ischemic heart disease or cancer, schizophrenia patients were less likely than others to have been diagnosed previously with these conditions (for ischemic heart disease, 26.3% compared with 43.7%; for cancer, 73.9% compared with 82.3%). The association between schizophrenia and mortality was stronger among women and the employed. Lack of antipsychotic treatment was also associated with elevated mortality.

Conclusions: Schizophrenia patients had markedly premature mortality, and the leading causes were ischemic heart disease and cancer, which appeared to be underdiagnosed. Preventive interventions should prioritize primary health care tailored to this population, including more effective risk modification and screening for cardiovascular disease and cancer.