Association of multimorbidity of non-communicable diseases with mortality: A 10-year prospective study of 0.5 million chinese adults

Objectives: Non-communicable diseases (NCDs) account for seven out of 10 deaths worldwide, whereas the pattern of multimorbidity of NCDs and its long-term impact on all-cause mortality remains largely unknown, especially among the Chinese population. This study aimed to investigate the associations between the number and patterns of multimorbidity with long-term risks of mortality and to estimate the influence of age on the relationship between multimorbidity and mortality.Study design: This was a prospective population-based cohort study.Methods: Data were obtained from the China Kadoorie Biobank study, which enrolled adults aged 30-79 years from 10 regions of China. The outcome was all-cause mortality, which was measured at a 10-year follow-up (9.93 ± 1.82 years). A principal component analysis (PCA) was used to identify patterns of individuals with multimorbidity based on 16 self-reported or baseline-detected chronic conditions. Cox proportional hazards models were used to examine the associations of both the number and patterns of multimorbidity of NCDs with all-cause mortality. Stratified analyses were carried out to explore whether the associations of multimorbidity with all-cause mortality were modified by age, number, and the patterns of multimorbidity.Results: We included 512,712 individuals in our analysis, of which 176,619 (34.5%) had only one long-term condition (LTC), and 81,360 (15.9%) had multimorbidity. The crude mortality rate was highest in those aged between 70 and 79 years who also had ≥4 LTCs (44.38 per 1000 person-years). In participants with at least four LTCs at baseline, fully adjusted HRs were 4.58 (95% CI 2.65-7.93) for people belongs to 1960s-1970s, compared to 2.73 (95% CI 2.50-2.97) for 1920s-1930s. Six multimorbidity patterns were identified, including cardiometabolic syndrome, respiratory diseases, digestive/renal/urologic diseases, articular/rheumatic diseases, and neuropsychiatric diseases. For the multimorbidity patterns of cardiometabolic syndrome, fully adjusted HRs for all-cause mortality were 1.60 (95% CI 1.55-1.65) in participants with one LTC and 8.19 (95% CI 6.45-10.40) in those with four LTCs compared with the reference group (no LTCs).Conclusions: The observed higher risk of mortality in younger people with multimorbidity, as middle aged (30-49 years), calls for advocating primary prevention in the younger population and secondary prevention for the elderly to strengthen early detection and timely treatment. Health systems need to shift from single-disease models to more effective multimorbidity management