Determinants and geographical variations in oral traditional Chinese medicine use among middle-aged and elderly chronic adults in China: a cross-sectional study

Introduction: As the population ages, the numerous middle-aged and older adults with chronic diseases strain healthcare resources and the economy. Traditional Chinese medicine (TCM) has unique benefits in managing these conditions. We aimed to analyze the use and determinants of oral TCM among middle-aged and elderly adults with chronic diseases in China. Methods: Data from the 2018 China Health and Retirement Longitudinal Study included 13,791 participants aged ≥ 45 years with one of 12 predefined chronic diseases. Provincial units were used to analyze the current use of oral TCM. Logistic regression and machine learning algorithms were employed to identify determinants, with the optimal algorithm selected for variable importance analysis. Results: In the 2018 wave, the prevalence of current oral TCM use among adults aged ≥ 45 years with chronic diseases in China was 26.84 % (95 % CI: [26.10 % - 27.58 %]), with the highest prevalence in the West (Qinghai) at 46.97 % (95 % CI: [38.46 % - 55.48 %]) and lowest in the East (Zhejiang) at 13.36 % (95 % CI: [10.49 % - 16.23 %]). Northern regions, such as Inner Mongolia (38.13 % (95 % CI: [34.52 % - 41.74 %])), also had high prevalence. Multivariate analysis showed that age, gender, education level, region, number of comorbidities, body pain, and local medical satisfaction were all statistically significant factors. Gradient boosting machine analysis additionally highlighted Communist Party of China membership, religious beliefs, residence, and depressive symptoms as important predictors. Conclusion: Less than one-third of middle-aged and older adults with chronic diseases utilized oral TCM at the time of the survey, with regional variations: lower in the East, higher in the West, and marginally elevated in the North. Biological, psychological, social, policy, and political-ideological factors were associated with the use of TCM.