EXPLORING THE LINK BETWEEN SYSTEMIC IMMUNITY-INFLAMMATION INDEX AND OBESITY IN THE US POPULATION: NHANES STUDY INSIGHTS (2005-2020).

Objective: To explore the correlation between the systemic immunity-inflammation index (SII) and obesity, utilizing data from the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2020. Methods: This cross-sectional study included 137,888 adult participants with complete data on SII and obesity. SII was calculated using the formula: platelet count multiplied by the neutrophil count divided by the lymphocyte count. Obesity was defined as a body mass index (BMI) exceeding 30 kg/m2. Results: Multivariate linear regression analysis showed a significant positive correlation between SII and obesity (β = 0.19, 95% CI: 0.18, 0.20). Factors such as age, sex, education level, and smoking status significantly influenced this correlation. However, race, income-to-poverty ratio, hypertension, and diabetes did not significantly interact with the observed relationship (interaction p-value > 0.05). Conclusion: The study highlights a substantial link between elevated SII levels and the prevalence of obesity, indicating the potential of SII as a biomarker in obesity research. Further large-scale prospective studies are needed to better understand the role of SII in the pathophysiology of obesity.