Modifiable Determinants of Metabolic Syndrome in Middle-Aged Adults: A Cross-Sectional Analysis of a Nationally Representative Health Survey

AimsTo identify modifiable and nonmodifiable determinants of metabolic syndrome in adults aged 40–64 years and outline implications for nursing practice.DesignCross-sectional analysis of data from the 2023 Korea National Health and Nutrition Examination Survey (KNHANES), South Korea.MethodsWe analyzed adults aged 40–64 years using data from the 2023 KNHANES, a nationally representative health and nutrition survey of South Korea. Metabolic syndrome was defined according to established clinical criteria. Determinants included sociodemographic, behavioral, and biological factors. Survey-weighted analyses accounting for the complex sampling design were performed, including multivariable logistic regression to identify factors associated with metabolic syndrome. Only deidentified public data were used under existing ethical approvals.ResultsOlder age (≥ 50 years; OR = 2.02, 95% CI 1.60–2.55), rural residence (OR = 1.35, 95% CI 1.05–1.73), current smoking (OR = 1.48, 95% CI 1.13–1.95), and BMI ≥ 25 kg/m2 (OR = 8.87, 95% CI 7.21–10.90) were associated with higher odds of metabolic syndrome. In contrast, meeting physical activity recommendations (OR = 0.70, 95% CI 0.56–0.87), higher educational attainment (OR = 0.80, 95% CI 0.64–0.99), and sufficient vitamin D levels (OR = 0.79, 95% CI 0.64–0.97) were associated with lower odds.ConclusionDeterminants in middle age are largely modifiable, centering on tobacco use, physical inactivity, excess adiposity, and social context.Implications for the Profession and/or Patient CareNurses in primary and community settings can deliver brief counseling for smoking cessation, physical activity, weight management, and vitamin D optimization, prioritizing rural residents and adults with lower educational attainment.ImpactThis study addresses the growing burden of metabolic syndrome in middle adulthood and specifies nursing-actionable targets. The findings prioritize behavior change and weight management, with protective roles for education and vitamin D. The work can inform rapid assessment and brief interventions in primary and community care for adults aged 40–64 years, especially where rural residence and educational disadvantage are prevalent.Study Design and Reporting GuidelineThis research is a cross-sectional analysis. The STROBE checklist for cross-sectional studies is completed and submitted.Statistical Compliance Statement(a) Statistical methods adhered to JAN Statistical Guidelines and best practices for complex survey data. (b) The analysis accounted for the complex, multistage, stratified cluster design of KNHANES with appropriate weighting and Taylor-series linearization for variance estimation. (c) Model assumptions were examined; effect estimates are presented with 95% confidence intervals, and confounder adjustment is described in the Methods section. (d) The author (Kyeongmin Jang, RN, PhD) served as the author-statistician and accepts responsibility for the statistical methods and interpretation. (e) The author confirms that data coding, preprocessing, and analysis steps are documented and reproducible.