Conicity Index Associated with Adult Hearing Impairment: A Cross-Sectional Study Based on the National Health and Nutrition Examination Survey (2001-2018).

Abstract

Objective: This study aimed to evaluate the association of conicity index (C-index), a marker of abdominal obesity, with hearing impairment (HI) in US adults using data from the National Health and Nutrition Examination Survey (NHANES).

Methods: We conducted a cross-sectional investigation using data from nine NHANES cycles spanning from 2001 to 2018. The C-index was used as the independent variable, whereas HI-defined as a pure-tone average hearing threshold exceeding 25 dB HL-was the outcome measure. Multivariable logistic regression models were used to assess the association between C-index and HI, adjusting for potential confounders including age, sex, race/ethnicity, hypertension, diabetes, total cholesterol, haemoglobin and blood urea nitrogen. Dose-response relationships were evaluated using trend tests (P for trend) and restricted cubic spline (RCS) analysis. Subgroup analyses were performed to assess potential interaction effects.

Results: A total of 7394 adults aged 20-69 were included. Higher C-index values were significantly associated with an increased prevalence of HI. In the fully adjusted model, each unit increase in C-index was associated with 7.35-fold higher odds of HI (95% CI: 3.03-17.82, P < 0.01). When stratified into tertiles, individuals in the highest tertile had a 57% higher likelihood of HI compared to the lowest tertile (Odds Ratio = 1.57, 95% Confidence Interval: 1.14-2.18, P < 0.01). RCS analysis indicated a significant non-linear association (P for non-linearity < 0.05) with an inflection point at a C-index of 1.17. Subgroup analysis revealed significant interaction effects of C-index with gender, diabetes and hypertension (P for interaction < 0.05) but not with age (P > 0.05).

Conclusion: Higher C-index values are independently associated with greater odds of HI. Given the rising burden of obesity and its metabolic consequences, the C-index may serve as a practical tool for HI risk assessment, especially in populations with cardiometabolic risk factors.