Research methodology and participant selection
This research retrieved information on 70,190 participants from the NHANES spanning the years 2005–2018. NHANES applied a multi-stage stratified probability sampling technique to gather comprehensive information regarding health conditions, lifestyle, and nutritional status of population in America [15]. The complete dataset was rigorously filtered according to exclusionary parameters which involved: (1) aged < 20 years, aged > 60 years; (2) the presence of missing data on ED; (3) incomplete information of TyG, TyG-BMI and TyG-WC and (4) invalid questionnaires. Ultimately, the research involved a total of 10,324 participants. The overall process of selecting participant is exhibited in Fig. 1.
Definition and computation of obesity indices associated with TyG
The TyG index assesses IR by integrating FBG and TG levels. These indicators’ measurements were taken at the outset when collected their blood samples at the first time. Concurrently, body weight, height, and WC were recorded after physical examinations conducted at a mobile examination center. The TyG, TyG-WC as well as TyG-BMI indicators, were derived using the subsequent calculations: (1) TyG = ln [triglycerides (mg/dl) × glucose (mg/dl)/2]; (2) BMI = body mass (kg)/height2(m2); (3) TyG-WC = TyG×waist circumference; TyG-BMI = TyG×BMI.
Eating Status Questionnaires
The eating status was evaluated through NHANES questionnaires administered between 2005–2006 and 2017–2018, which inquired about the frequency of experiencing ED symptoms over the preceding half months. Their feedbacks were categorized as "not at all," "several days," "more than half the days," and "nearly every day," with scores allocated from 0 to 3.
Assessment of covariates
Age and poverty income ratio (PIR) was deemed as a continuous variable. According to gender, participants were grouped into males and females. Race/ethnicity involved in Mexican and non-Mexican Hispanics, non-Hispanic whites and blacks, along with others. They were divided into three groups by education level, including less than high school, high school graduate or equivalent as well as high school graduate or above. Marital status was divided into three groups, including married, widowed/divorced or separated and living with partner. Alcohol consumption was defined as how many alcoholic assumption per day in the past year. Weight, height and WC were assessed when attending a physical examination as continuous type variables. Besides, FBG, insulin, TG, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were tested at baseline when providing blood samples as continuous variables. Diabetes, hypertension, sleep trouble, congestive heart failure, tumor or malignancy and liver status were assessed (Doctor informed you had any condition yes or no). Furthermore, we incorporated consideration for weight and attempt to lose weight from weight history questionnaires
Statistical analyses
All data from the NHANES 2005–2006 to 2017–2018 was handled through Empower Stats (version 2.0), along with Microsoft Office Excel. Descriptive statistics were represented as mean ± standard deviation (SD) for continuous variables, and as the count (n) and percentage (%) for categorical variables. Taking into account the complex multistage probability sampling methodology used in the NHANES, the study paid careful attention to underlying impacts of sample weights, stratification, and clustering within the dataset. As a result, the research categorized the TyG index into quartiles and utilized a weighted multivariable logistic regression model to examine the relationships between TyG-associated obesity indicators and ED. To conduct a thorough analysis, we formulated three models into adjustment. Model 1 served as an unadjusted; model 2 was was adjusted for basic demographic variables concerning age, gender, and race; and model 3 subjected to adjustments for multiple possible confounders: age, gender, race, education level, marital status, PIR, alcohol consumption, diabetes, hypertension, sleep trouble, congestive heart failure, liver condition, cancer or malignancy, consideration for weight, attempt to lose weight, WC, BMI, HDL-C, LDL-C, insulin, fasting blood glucose, and fasting triglycerides.