Ten-year prospective cohort study on the dynamic changes of metabolic syndrome and its determinants in the adult population of Iran

Metabolic syndrome (MetS) is a risk factor for stroke, cardiovascular disease, and type 2 diabetes mellitus, with a global prevalence ranging from 12.5% to 31.4%. This ten-year prospective cohort study conducted in Shiraz, Iran, aimed to provide clinical evidence on the dynamics of MetS over time. Adults selected via multistage random cluster sampling were followed in 2014, 2019, and 2024. MetS was defined using ATP III and IDF criteria, and participants were categorized into unchanged, regressed, and progressed subgroups. Demographic, socioeconomic, anthropometric, medical, and paramedical characteristics were recorded. Nutritional status and physical activity were assessed using validated Persian versions of the FFQ-80 and IPAQ-7, respectively. Fatty liver was diagnosed by ultrasonography. Differences in quantitative variables (Δ) were calculated between phases. Longitudinal associations were examined using generalized estimating equations (GEE), and cross-sectional associations were assessed via univariable, binary logistic, and ordinal logistic regression analyses in SPSS version 24. The study followed 296 adults with a mean age of 42.4 ± 11.9 years and a female-to-male ratio of 1.2. According to IDF criteria, MetS prevalence in phases one, two, and three was 19.6%, 37.2%, and 41.2%, respectively. Using ATP III criteria, prevalence was 19.9%, 39.5%, and 33.4%, respectively. Analysis showed that negative changes in triglycerides (Δ-TG: OR = 0.99), fasting blood sugar (Δ-FBS: OR = 0.98), and diastolic blood pressure (Δ-DBP: OR = 0.97) were determinants of regression of MetS. On the other hand, positive changes in waist circumference (Δ-WC: OR = 1.07), systolic blood pressure (Δ-SBP: OR = 1.03), uric acid (OR = 1.02) and triglycerides (Δ-TG: OR = 1.01), along with negative change in HDL (Δ-HDL: OR = 0.97), were determinants of progression of this syndrome. In the third phase, female gender (OR = 6.67), low education (OR = 1.86), hyperuricemia (OR = 1.56), and increasing age (OR = 1.04) were positively correlated with MetS. In conclusion, MetS may regress or progress over time. Regression is possible by controlling diastolic blood pressure, blood glucose, and triglycerides, while uncontrolled waist circumference, systolic blood pressure, uric acid and triglycerides, along with low HDL, increase progression likelihood.