Multimorbidity among persons aged 25-64 years: a population-based study of social determinants and all-cause mortality.

Abstract Background Despite increasing multimorbidity across the lifespan, little is known about the co-occurrence of conditions and risk factors among younger adults. This population-based study examines multimorbidity, social determinants and associated mortality among younger and middle-age adults. Method Analysis was based on the Northern Ireland population aged 25–64 years enumerated in the 2011 Census (n = 878 345), with all-cause mortality follow-up to 2014 (8659 deaths). Logistic regression was used to examine social determinants and Cox proportional hazards models in the analysis of associated mortality. Results Prevalence of multimorbidity was 13.7% in females and 12.7% in males. There was a strong association between multimorbidity that included mental/cognitive illness and deprivation. Among those never married, multimorbid physical conditions were less likely [relative risk ratios (RRR) = 0.92: 95% confidence interval (CI) = 0.88, 0.95 for males; and RRR = 0.90: 0.87, 0.94 for females]. Rurality was associated with lower physical multimorbidity (RRR = 0.92: 0.89, 0.95) but higher mental/cognitive multimorbidity (RRR = 1.35: 1.12, 1.64) among females. All multimorbid categories were associated with elevated risk of mortality. Conclusion The health and economic challenges created by multimorbidity should be addressed further ‘upstream’. Future multimorbidity research should include younger adults to inform the development of preventative interventions and align health and social care services more closely with patients’ needs.