Weight-adjusted waist index and lung health ‒ Uncovering a hidden link between central obesity and respiratory risk.

Background

central obesity is a known contributor to impaired lung function and chronic respiratory disease (CRD). The weight-adjusted waist index (WWI), a novel anthropometric measure, may better capture this association, revealing an underrecognized link with respiratory health. This study aimed to investigate the relationship between WWI, lung function, and CRD.

Methods

we conducted a cross-sectional analysis using data from the 2007-2012 National Health and Nutrition Examination Survey (NHANES). WWI was calculated by dividing waist circumference by the square root of body weight. Lung function parameters and CRD prevalence were analyzed using univariate and multivariate regression models. Restricted cubic spline (RCS) analysis was used to assess nonlinear relationships, and subgroup and interaction analyses were performed.

Results

Among 9,437 participants, higher WWI was significantly associated with lower values of FEV₁, FVC, PEF, and FEF₂₅-₇₅ %. Each unit increase in WWI corresponded to a 319.21 ml decrease in FVC and a 248.42 ml decrease in FEV₁. No significant association was found with the FEV₁/FVC. A 1-unit increase in WWI was associated with a 20 % increase in the prevalence of CRD. RCS analysis revealed a U-shaped relationship between WWI and CRD risk, with an inflection point at WWI = 10.60. Below this threshold, CRD risk decreased with increasing WWI, but beyond 10.60, the risk increased nonlinearly, suggesting that high WWI levels are associated with increased CRD risk.

Conclusion

elevated WWI is independently associated with reduced lung function and increased CRD risk. WWI may serve as an effective, simple indicator for identifying individuals with unrecognized respiratory risk in population health screenings.