Excess mortality and its causes among older adults with schizophrenia versus those with bipolar disorder and major depressive disorder: a 5-year prospective multicenter study

Excess mortality observed in people with schizophrenia may persist in later life. The specific causes of increased mortality observed in older adults with schizophrenia and the potential influence of psychotropic medications remain partly unknown. We compared 5-year mortality and its causes of older adults with schizophrenia to bipolar disorder (BD) or major depressive disorder (MDD). We used a 5-year prospective cohort, including 564 older inpatients and outpatients with schizophrenia, BD or MDD (mean age: 67.9 years, SD = 7.2 years). Causes of death were cardiovascular disorder (CVD) mortality, non-CVD disease-related mortality (e.g., infections), suicide, and unintentional injury. The primary analysis was a multivariable logistic model with inverse probability weighting (IPW) to reduce the effects of confounders, including sociodemographic factors, duration and severity of the disorder, and psychiatric and non-psychiatric comorbidity. Five-year all-cause mortality among older participants with schizophrenia and with BD or MDD were 29.4% (n = 89) and 18.4% (n = 45), respectively. Following adjustments, schizophrenia compared to MDD or BD was significantly associated with increased all-cause mortality (AOR = 1.35; 95%CI = 1.04-1.76; p = 0.024) and cardiovascular mortality (AOR = 1.50; 95%CI = 1.13-1.99; p = 0.005). These associations were significantly reduced among patients taking antidepressants [interaction odds ratio (IOR) = 0.42; 95%CI = 0.22-0.79; p = 0.008 and IOR = 0.39: 95%CI = 0.16-0.94; p = 0.035, respectively]. Schizophrenia was associated with higher mortality compared to BD or MDD. Cardiovascular diseases explained most of this excess mortality. Exploratory analyses suggested that psychotropic medications did not influence this excess mortality, except for antidepressants, which were associated with significantly reduced between-group difference in all-cause and cardiovascular mortality.