Racial/ethnic differences in the prevalence and incidence of metabolic syndrome in high-income countries: a protocol for a systematic review

BACKGROUND: Metabolic syndrome is a constellation of various cardiovascular and type 2 diabetes risk factors, such as abdominal obesity, atherogenic dyslipidemia, high blood pressure, and high blood glucose, but its prevalence varies widely by geographical region, sex, and race/ethnicity. The objective of this study is to examine the prevalence and incidence of metabolic syndrome among adults of different racial/ethnic origins in high-income countries. METHODS: We designed and registered a study protocol for a systematic review of descriptive epidemiological data. Observational studies (e.g., cross sectional and cohort studies) reporting morbidity data of metabolic syndrome and conducted in a wide range of adult people (e.g., different racial/ethnic origins, including migrants) will be included. The primary outcome will be the prevalence and incidence of metabolic syndrome. Secondary outcomes will be the prevalence and incidence of individual components of metabolic syndrome (e.g., abdominal obesity, dyslipidemia, high blood pressure, and high blood glucose). Literature searches will be conducted in several electronic databases (from inception onwards), including MEDLINE, Web of Science Core Collection (Science Citation Index and Social Science Citation Index), CINAHL, and Cochrane Library. Two investigators will independently screen all reference titles, abstracts, and full-text articles. The methodological quality (or potential bias) of selected studies will be appraised using an appropriate tool. Our results will be described narratively. Random-effects meta-analysis will be conducted, if feasible and appropriate. Additional analyses will be conducted to explore the potential sources of heterogeneity. CONCLUSION: This systematic review will identify, evaluate, and integrate prevalence and incidence data of metabolic syndrome, with focus on racial/ethnic differences in high-income countries. We anticipate our findings may guide policy formulation and identify knowledge gaps in the literature that future research should address. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD42020157189