2.2. Data collection and definition

For the assessment of ED, participants were asked to evaluate their competence to achieve and maintain an erection sufficient to enable sexual intercourse in the 2001-2004 information collection, and the response options were “never”, “sometimes”, “usually”, and “almost often or almost always”, and we classified subjects who answered “never” or “sometimes” as individuals with ED. In the sensitivity analysis, only men who selected “never” were considered to suffer from ED (12). Based on these, we started a correlation analysis to uncover the factors associated with ED. The target variable for our primary study was NLR, which was analyzed for neutrophil and lymphocyte counting by whole blood count from a Beckman Coulter automated analyzer. Detailed analysis procedures are described in Chapter 7 of the NHANES Laboratory/Medical Technician Procedures Manual (https://wwwn.cdc.gov/nchs/nhanes/).

Covariates including age, BMI, race, marital status, education, alcohol consumption status, poverty income ratio, smoking status, history of diabetes, and history of hypertension were selected for analysis. The results of BMI were divided into three groups: BMI ≤ 25, 25 < BMI ≤ 30, and BMI > 30. Race was classified as Mexican American, Non-Hispanic White, Non-Hispanic Black, Other Hispanic, and other races. Educational attainment was divided into less than high school, high school, and high school or higher. The marital status was divided into: married/cohabiting with partner and living alone. The poverty income ratio (PIR) is an index of the household income to poverty ratio, which reflects social economic status. These guidelines are published annually by the Department of Health and Human Services (HHS) and are categorized as PIR ≤ 1.3, 1.3 < PIR ≤ 3.5, and PIR > 3.5. These covariates were considered potential confounders that may affect the relationship between NLR and ED and were included in the multivariate model.