2.1 Study design and participants
The National Health and Nutrition Examination Survey (NHANES) is an ongoing national study that provides extensive data on the dietary habits and general health of Americans. Prior to data collection, written informed consent was obtained from all participants, and all study protocols were approved by the National Center for Health Statistics' ethical review board. Further information about the NHANES survey can be found at NHANES.
This cross-sectional study utilized data from the NHANES (2005–2008 and 2015–2018) and included patients aged 20 years and above (n = 22,202). Participants with missing data required to calculate BMI, WC, BRI, LAP, VAI, ABSI, or WWI were excluded (n = 13,235). Additionally, data for patients diagnosed with obstructive sleep apnea syndrome (n = 1) were excluded from the analysis. The final number of subjects included in the analysis was 8,966.
2.2 Definitions of the exposure and outcome variables
The exposure variables include body mass index (BMI), waist circumference (WC), body roundness index (BRI), lipid accumulation product (LAP), visceral adiposity index (VAI), a body shape index (ABSI), and weight-to-waist index (WWI). The data pertaining to these variables were obtained from the body measurements section of the NHANES database. The formulas for these indices are as follows:
In accordance with earlier studies, OSA is diagnosed when a person answers 'yes' to at least one of the following three NHANES questions[22]: (1) feeling excessively sleepy during the day despite getting at least 7 hours of sleep per night, as reported 16–30 times; (2) experiencing episodes of gasping, snorting, or stopping their breath on three or more occasions per week; (3) snoring on three or more occasions every week.
2.3 Potential covariates
The self-reported sociodemographic characteristics included age,sex (male/female), race/ethnicity (non-Hispanic White, Mexican American, non-Hispanic Black, other Hispanic, or other Race/multiple Races), education level (less than high school, completed high school, or more than high school), and marital status (married/living with a partner, never married, widowed, divorced, or separated). Physical activity was assessed by asking participants to report the types of physical activities they engaged in regularly, categorized into vigorous physical activities (e.g., running, playing basketball) and moderate physical activities (e.g., brisk walking, swimming, cycling). Alcohol consumption and smoking status were also treated as categorical variables.
Alcohol consumption was classified into two categories, "Yes" and "No," based on respondents' answers to the question: "Have you consumed at least 12 alcoholic drinks in the past year?" The participants were divided into three smoking categories: never smokers (smoked fewer than 100 cigarettes), former smokers (smoked at least 100 cigarettes but not currently smoking), and current smokers (smoked at least 100 cigarettes and currently smoking daily or some days). The definition of metabolic syndrome (MetS) was in accordance with the updated National Cholesterol Education Program/Adult Treatment Panel III criteria for Americans [23]. Additionally, total cholesterol concentrations were quantified using the enzymatic method. This method utilizes a single-reagent endpoint reaction, which is highly specific for cholesterol, ensuring accurate and reliable measurements of cholesterol levels in the samples.
To address missing values in the dataset, the mean values for total cholesterol (TC) and the ratio of family income to poverty (PIR) were imputed. The confounding variables and their detailed definitions are collated in Table S1 for reference.
2.4 Statistical analyses
The analyses presented in this study were conducted via the R statistical computing environment (version 4.4.0). The statistical analyses were conducted in accordance with the recommendations and guidelines set forth by the NHANES, utilizing the appropriate sampling weights. This approach accounted for the complex multistage entire cohort survey design. A p value of less than 0.05 was considered to indicate a statistically significant result. The associations between seven anthropometric indices and OSA were investigated via multivariate logistic regression models in four different models. The crude model was not adjusted for covariates, whereas Model 1 was adjusted for age, sex, and race/ethnicity. Model 2 was adjusted for the variables in Model 1, in addition to education level, marital status, physical activity, smoking status, and alcohol status. Model 3 was adjusted for the variables in Model 2, in addition to metabolic syndrome and total cholesterol. A further assessment of the heterogeneity between seven anthropometric indices and OSA was conducted through subgroup analysis, which included the following variables: age, sex, race/ethnicity, smoking status, alcohol consumption, marital status, physical activity and metabolic syndrome.
Moreover, we conducted a receiver operating characteristic (ROC) curve analysis to illustrate the connection between the indices and the probability of developing OSA, with the reference value set at the median. Furthermore, the capacity of the indices to identify OSA was evaluated via receiver operating characteristic (ROC) analysis and area under the curve (AUC) values. The AUC values of the BRI and BMI were compared via the Bonferroni correction and DeLong test[24][25].