Abstract
BACKGROUND: Given the robust correlation between MAFLD and OSA, FSI may act as a potential indicator for OSA risk. Nevertheless, the correlation between FSI and OSA, along with the potential mediating mechanisms, remains unclear. METHODS: Our study examined 46,028 NHANES participants from 2005 to 2008 and 2015 to 2020. FSI-OSA correlation was assessed using weighted multivariate logistic regression models, restricted cubic spline curve analysis, threshold effects analysis, and subgroup analysis. We also conducted mediation studies to determine if waist-to-height ratio (WHtR) mediates the FSI-OSA relationship. RESULTS: Each unit increase in the FSI was associated with a 36% higher odds of OSA (OR = 1.36; 95% CI: 1.31-1.42). FSI quartiles were positively associated with OSA in aggregate analyses, with adjustment for potential confounders. RCS curves and threshold studies showed a nonlinear link between FSI and OSA risk when FSI was steeper on the left side of the inflection point (- 1.108) and levelled out on the right. WHtR also partially mediated the FSI-OSA connection, accounting for 24.5% of the total effect. CONCLUSION: FSI and OSA were positively correlated with nonlinear and threshold effects in this study. Elevated FSI values were associated with a higher risk of OSA.