Inequalities in premature mortality: a nationwide cohort study in 4.3 million people in England diagnosed with multimorbidity under age 60

Background Multimorbidity is common in working-age adults, yet the contribution of social and demographic factors to premature mortality is underexplored. Aim To quantify social, demographic, and clinical determinants of premature mortality among adults with multimorbidity in England. Method We conducted a retrospective cohort using CPRD Gold and Aurum linked to hospital and mortality records (1987–2020). Adults aged 18–60 years at incident multimorbidity were included and followed until death, censoring, or age 75. Premature mortality was death before 75. Cox models estimated adjusted hazard ratios (HRs) for social care need (disability, financial support, residential care), deprivation, ethnicity, region, age, sex, and multimorbidity burden. Results The cohort included 4.3 million individuals, with 572,000 premature deaths. Residential care showed the greatest 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). A clear deprivation gradient was observed, with individuals in the most deprived quintile having higher mortality risk than those in the least deprived (HR 1.61, 95% CI 1.59–1.62). Men had higher risk than women (HR 1.47, 95% CI 1.46–1.48). Compared with White individuals, risk was lower in Asian, Black, Mixed, and Other ethnic groups. In regional differences, compared to London, risk was higher in the East Midlands and East England, and lower in the Southwest. Conclusion Premature mortality in multimorbidity is patterned by social vulnerability, particularly residential care, deprivation, and financial hardship. Targeted policy and service responses for these high-risk groups are needed to reduce inequalities and improve outcomes in working-age adults.