Inequity in Premature Mortality: A Cohort Study of 4.3 million Adults Under 60 years With Multimorbidity

Background : Multimorbidity is increasingly common among adults who develop multiple long-term conditions before age 60 and is linked to premature mortality. We examined whether socioeconomic disadvantage and recorded markers of structural vulnerability were associated with premature mortality in this population using the CORE20PLUS5 and PROGRESS-PLUS frameworks. Methods : We conducted a population-based cohort study using linked Clinical Practice Research Datalink (CPRD) Gold and Aurum data from England, 1987–2020. Adults aged 18–60 years with incident multimorbidity were followed until death, deregistration, study end, or age 75 years. Premature mortality was defined as all-cause death at or before age 75 years. Cox proportional hazards models estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for socioeconomic, demographic, and clinical factors. Results : Among 4,303,353 adults with incident multimorbidity, 447,720 premature deaths occurred. Mortality risk was higher in the most deprived than the least deprived areas (HR 1.61, 95% CI 1.59–1.62). Recorded residential care was associated with the highest mortality risk (HR 2.92, 95% CI 2.89–2.95), followed by financial support (HR 1.44, 95% CI 1.42–1.47) and disability (HR 1.26, 95% CI 1.24–1.27). Women had a lower risk than men (HR 0.68, 95% CI 0.68–0.69). Adults aged 40–60 years at multimorbidity onset had a higher risk than those aged 18–39 years (HR 2.29, 95% CI 2.27–2.30). Compared with White individuals, Asian, Black, Mixed, and Other ethnic groups had lower adjusted risks. Mortality risk was also higher in several regions outside London. Conclusions : In adults who developed multimorbidity before age 60, premature mortality before age 75 was strongly patterned by socioeconomic disadvantage and recorded markers of structural vulnerability. These variables should be interpreted as markers of heightened vulnerability rather than direct causal determinants of mortality. Equity-oriented prevention and coordinated health and community care may help reduce avoidable inequalities.