Association between weight-adjusted-waist index and α1-acid glycoprotein levels among adult females: Evidence from NHANES 2015–2020

Obesity is a prevalent issue in daily life, and previous studies have demonstrated a correlation between inflammation and obesity. Additionally, some studies have investigated the relationship between inflammation and body mass index, a widely used indicator of obesity. In recent years, the weight-adjusted waist circumference index (WWI) has been introduced and increasingly utilized in the clinical assessment of obesity and overweight. However, its relationship with the inflammatory marker α1-acid glycoprotein (AGP) remains unclear. In this study, we analyzed data from 2899 adult women (mean age 33.42 ± 9.27 years) from the National Health and Nutrition Examination Survey (2015-2020). The WWI was calculated as the square root of waist circumference divided by body weight. Multiple linear regression analysis and smooth curve fitting were performed to validate the results. Finally, the relationship between WWI, AGP, and various clinical factors, including educational status, age, and hypertension incidence, was analyzed. Subgroup analysis and interaction tests were performed during the analysis. This study included 2899 adult female participants (mean age 33.42 ± 9.27 years). The mean levels of WWI and AGP were 10.97 ± 0.83 and 0.79 ± 0.24 g/L, respectively. In the fully adjusted model, multiple linear regression analysis revealed a significant positive correlation between WWI and AGP levels, with each unit increase in WWI associated with a 0.06 g/L increase in AGP (β = 0.06, 95% CI: 0.05-0.07). When WWI was categorized into quartiles, AGP levels in the highest quartile were 0.13 g/L higher than those in the lowest quartile (β = 0.13, 95% CI: 0.10-0.15). Moreover, smooth curve fitting identified an inflection point in this relationship at a WWI value of 11.78. In the adult female population in the United States, WWI and AGP exhibited a significant positive correlation.