Longitudinal trajectories of disability among Chinese adults: the role of cardiometabolic multimorbidity

Cardiometabolic multimorbidity (CM) has been found to be associated with higher mortality and functional limitations. However, few studies have investigated the longitudinal association between CM and disability in the Chinese population and whether these associations vary by smoking status.

The study included 16,754 participants from four waves (2011, 2013, 2015, and 2018) of China Health and Retirement Longitudinal Study (CHARLS) (mean age: 59, female: 51%). CM was assesed at baseline and defined as having two or more of diabetes, stroke, or heart disease. Disability was repeatedly measured by summing the number of impaired activities of daily living (ADL) and instrumental activities of daily living (IADL) during the 7-year follow-up. Linear mixed-effects model was used to determine the association of CM and trajectories of disability and to assess the modification effect of smoking status in these associations.

Participants with CM at baseline had a faster progression of disability compared to those without CM (CM: β = 0.13, 95% CI: 0.05 to 0.21). Current smokers with CM developed disability faster than their counterparts (P_{interaction for smoking}=0.011). In addition, there was a significant association between CM and the annual change of disability in current smokers (β = 0.34, 95% CI: 0.17 to 0.50) while no such association was observed in current non-smokers (β = 0.08, 95% CI: -0.02 to 0.17).

CM was associated with more a rapid disability progression. Notably, being current smokers may amplify the adverse effects of CM on disability progression.