Association between metabolic syndrome and body constitution of traditional Chinese medicine: A systematic review and meta-analysis

Abstract Background The constitution theory of traditional Chinese medicine (TCM) states that body constitution and disease are associated; therefore, the identification of body constitution can provide reference for disease prevention and treatment. A series of clinical studies evaluating the association between TCM constitution and metabolic syndrome (MetS) have been conducted in recent years. The aim of this systematic review is to summarize and evaluate the clinical evidence of the relationship between constitution and MetS. Methods The PubMed, Embase, China National Knowledge Infrastructure (CNKI), Chongqing VIP, and Wanfang Data electronic databases were searched from April 2009 to July 2020. The search terms included “metabolic syndrome,” “constitution,” and “Chinese medicine.” Observational studies evaluating the relationship between body constitution of TCM and MetS were included. The primary outcome included the distribution of constitutional types in the MetS population, and odds ratio (OR) or relative risk (RR) between constitution and MetS. Effect size was expressed as proportion or OR with 95% confidence interval (CI). Methodological quality of included studies was evaluated by the Newcastle–Ottawa Scale (NOS) or the American Agency for Healthcare Research and Quality (AHRQ) criteria. Results Three case–control and 26 cross-sectional studies involving 30 435 cases were included. Phlegm-dampness, qi-deficiency, and damp-heat were the main constitution types in patients with MetS, accounting for 29% (22%–39%), 18% (13%–24%), and 12% (9%–17%) of the population, respectively; the risk of MetS in people with phlegm-dampness and qi-deficiency constitution was 1.74 [1.27, 2.38] and 1.29 [1.01, 1.65] times higher than that in those with other constitutions. There were sex- and age-related differences in the distribution of TCM constitution in patients with MetS. Conclusion Phlegm-dampness and qi-deficiency were associated with the occurrence of MetS. Well-designed cohort and case–control studies are needed to provide evidence for the use of TCM to prevent and treat MetS.