Cause-specific mortality in individuals with and without mental disorders according to socioeconomic position: a...

Mental disorders are associated with elevated cause-specific mortality rates; however, the role of socioeconomic position (SEP) on these associations remains unclear. We aimed to examine cause-specific mortality associated with diverse mental disorders by SEP, on both relative and absolute scales.

This cohort study included all residents of Denmark on January 1, 2000, and followed them until December 31, 2020. Information on mental disorders, SEP (income percentile, further categorized into low [<20%], middle [20-79%], and high [≥80%]), and cause-specific mortality was obtained from nationwide registers. We estimated mortality rate ratios (MRRs) and rate differences (MRDs) with Poisson regression models.

Overall, 5,316,626 individuals (50.6% females, median age 38.3 years) were followed up to 21 years. People with mental disorders (versus without) experienced higher mortality rates from all 11 specific causes of death, regardless of SEP. MRDs (per 10,000 person-years) between people with versus without mental disorders were greater in the lower than the higher SEP groups for all 11 causes of death, except suicide where MRDs were largest in the high-SEP group (9.3 [95% CI 8.6-9.9] versus 7.2 [7.0-7.5] in middle- and 6.1 [5.8-6.4] in low-SEP groups). MRRs were similar across SEP groups for most causes, with a 30-40% increase for cancer-related deaths, and more than two-fold increase for other cause-specific deaths. Conversely, relative risks of dying from alcohol misuse and suicide were higher among the high-SEP groups (MRRs: 10.9 [95% CI 9.9-12.0] and 17.7 [16.0-19.6] respectively) than the middle-SEP (8.3 [8.0-8.6] and 11.1 [10.6-11.7]) or low-SEP (4.8 [4.6-5.0] and 7.9 [7.3-8.6]) groups. All subgroup, sensitivity, and post-hoc analyses indicated similar patterns.

We provide detailed descriptions of cause-specific mortality associated with specific mental disorders by SEP and reveal potentially differential roles of SEP across causes of death.

Independent Research Fund Denmark.