Social exclusion as a determinant of excess mortality in people with schizophrenia-spectrum and bipolar disorders: retrospective cohort study in 0.5 million people

Background People with severe mental illness (SMI) (schizophrenia-spectrum and bipolar disorders) experience a 15–20-year reduction in life expectancy. The role of social determinants, including that of social exclusion, in contributing to excess mortality in SMI remains underexplored. Methods Retrospective cohort study, comprising 8098 people with clinician-diagnosed SMI, matched to 581,209 population controls, followed for 5.7 years using person-level linked health/ census records. A social exclusion index was derived from census indicators: marital status, social isolation, economic inactivity, education, tenure, housing stability, and material assets. Results Social exclusion was more common in SMI than in controls and strongly associated with higher mortality. Relative to the least socially excluded controls, adjusted hazard ratios (aHR) for mortality in SMI were: 16–44 years: aHR 7.58 (95% CI: 2.75–20.86) in the least socially excluded, increasing to 12.34 (7.92–19.24) in the most excluded; 45–64 years: 3.34 (1.98–5.64) [least excluded] increasing to 6.58 (5.32–8.14) [most excluded]; 65+ years: 2.71 (1.90–3.86) [least excluded], increasing to 3.07 (2.48–3.80)[most excluded]. Excess mortality among those with SMI was pronounced at younger ages if never married; by mid-life if living alone or economically inactive; and at 65+ years in those with SMI living alone, renting, or with no car ownership. Economic inactivity and lack of qualifications accounted for 16–35% of SMI mortality. Conclusions Social exclusion is an under-recognized contributor to premature mortality in SMI. Targeting social determinants through novel socially-focused interventions could improve survival in people with SMI.