Over-time changes in the prevalence of metabolic syndrome and its components among elderly population in Iran from 2016 to 2021; A nation-wide study

Background: The prevalence of Metabolic Syndrome (MetS) increases with aging, significantly contributing to the rising burden of non-communicable diseases (NCDs). This study aimed to investigate over-time changes in the prevalence of MetS and its components among the elderly population of Iran. Methods: We analyzed data from the 2016 and 2021 national STEPwise approach to non-communicable disease risk factor Surveillance (STEPS) for participants aged ≥65 who completed all three survey steps (questionnaire-based assessments, physical measurements, and laboratory tests) with no missing data on MetS components. According to the STEPS protocol, individuals with severe mental disorders, physical limitations that prevented measurements, or inability to provide laboratory samples were excluded. Using survey analysis techniques and weights, we ensured the findings are nationally representative. MetS was defined using the following criteria: National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII), International Diabetes Federation (IDF), American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI), and Joint Interim Statement (JIS). Regional IDF (RIDF) and regional JIS (RJIS) were defined by ethnicity-specific values of waist circumference. Results: This study included 4,000 elderly participants in 2016 and 3,849 in 2021, with a mean age of 74 and 72 years, respectively. Approximately 50% were female in both years, and the proportion of urban residents increased from 67% in 2016 to 75% in 2021. The national prevalence of MetS among the elderly increased significantly from 46.11%−66.38% in 2016 to 54.15%−73.98% in 2021 across different criteria, with an annual percent change of 2.19%−3.26%. Prevalence was higher in females and urban populations, while males showed a greater increase. High blood pressure, low high-density lipoprotein cholesterol, and central obesity were the most common components of MetS, while elevated triglycerides and high fasting plasma glucose showed the largest increases over time. Conclusions: The escalating prevalence of MetS in the elderly is a matter of increasing concern, underscoring the need for targeted policy interventions aimed at promoting healthy aging, empowering the elderly, and advocating for lifestyle modifications.