Multimorbidity patterns and their associations with sociodemographic factors, lifestyle behaviors, and mental health status among older adults in the frigid zone of China

Multimorbidity represents a critical global public health challenge, particularly in aging populations. Older adults face heightened risks due to extreme cold climates and accelerated aging-related health decline. This study explores the prevalence of multimorbidity among older adults in China’s frigid zones, characterizes distinct disease clusters, and examines their associations with sociodemographic factors, lifestyle behaviors, and mental health status. Data were drawn from five waves of the China Health and Retirement Longitudinal Study (CHARLS; 2011, 2013, 2015, 2018, and 2020) and included adults aged ≥ 60 years. The analytical framework involved: (i) estimating survey-weighted prevalence of multimorbidity across 14 chronic diseases and comparing these estimates between frigid and non-frigid zones; (ii) applying latent class analysis to identify clinically meaningful multimorbidity patterns among older adults in the frigid zone; (iii) using the R3STEP approach to examine associations of multimorbidity patterns with sociodemographic factors, lifestyle factors, and mental health status. Survey-weighted multimorbidity prevalence among older adults in the frigid zone was 52.85% in 2011 and 73.21% in 2020, and it was higher than the corresponding estimates in the non-frigid zone and the overall population in each survey wave. Wave-specific LCA yielded two classes in 2011, three in 2013 and 2015, and four in 2018 and 2020. Relatively healthy, cardiometabolic, respiratory-related, and multisystem classes recurred across different waves, while a respiratory-dominant class was identified in 2020. In the 2018 cross-sectional analysis, membership in the cardiometabolic class was less likely among men (RRR = 0.49, 95% CI: 0.28–0.85) and rural residents (RRR = 0.47, 95% CI: 0.30–0.74), and was positively associated with depressive symptoms (RRR = 1.68, 95% CI: 1.05–2.68). For the multisystem class, rural residence (RRR = 0.46, 95% CI: 0.27–0.78) and current alcohol consumption (RRR = 0.47, 95% CI: 0.24–0.91) were inversely associated with class membership, whereas sleep duration < 6 h (RRR = 2.52, 95% CI: 1.56–4.07) and depressive symptoms (RRR = 5.47, 95% CI: 3.21–9.32) were positively associated with class membership. Smoking was positively associated with the respiratory-multisystem class (RRR = 2.39, 95% CI: 1.17–4.88), while rural residence (RRR = 0.49, 95% CI: 0.26–0.92) and physical activity (RRR = 0.42, 95% CI: 0.19–0.92) showed inverse associations. The inverse association with alcohol consumption should be interpreted cautiously given the binary assessment of current drinking status. Multimorbidity was highly prevalent among older adults living in China’s frigid zone, and the survey-weighted prevalence was more pronounced in 2020 than in 2011. Although the number and composition of latent classes varied between survey periods, several recurring multimorbidity patterns were observed. The 2018 analysis further showed that sociodemographic, lifestyle, and mental health factors were associated differently with distinct multimorbidity patterns. These findings provide empirical support for developing targeted prevention strategies tailored to this population.