Prevalence and Interplay of Modifiable and Genetic Determinants of Eustachian Tube Dysfunction Among Saudi Adults: A Nationwide Study

<b>Background/Objectives</b>: Eustachian Tube Dysfunction (ETD) is a prevalent condition affecting middle ear pressure regulation, yet nationwide epidemiological data in Saudi Arabia remain limited. This study aimed to assess the prevalence of ETD and identify its associated factors among Saudi adults using a validated screening tool. <b>Methods</b>: A nationwide cross-sectional study was conducted between June 2024 and March 2025 among 1124 Saudi adults (aged ≥ 18 years) across five geographic regions. ETD was assessed using the validated Arabic version of the seven-item Eustachian Tube Dysfunction Questionnaire (ETDQ-7), with scores ≥ 14.5 indicating dysfunction. Data on demographic, anthropometric, clinical, and lifestyle characteristics were collected via an online questionnaire. Multiple linear regression analysis identified independent predictors of ETDQ-7 scores, with statistical significance set at <i>p</i> < 0.05. <b>Results</b>: The prevalence of ETD was 33.9% (95% CI: 31.1-36.8%), substantially higher than the 7% self-reported rate. Of affected participants, 29.6% had mild-to-moderate ETD and 4.3% had severe dysfunction. Multivariable regression analysis identified four significant independent predictors: higher body mass index (BMI) (β = 0.08; 95% CI: 0.03-0.16; <i>p</i> = 0.049), family history of hearing loss (β = 1.87; 95% CI: 0.90-2.83; <i>p</i> < 0.001), prior bariatric bypass surgery (β = 14.37; 95% CI: 3.33-25.41; <i>p</i> = 0.011), and allergies (β = 3.19; 95% CI: 2.30-4.07; <i>p</i> < 0.001). No significant associations were found with demographic factors, smoking, or other comorbidities. <b>Conclusions</b>: ETD affects approximately one-third of Saudi adults, with significant underdiagnosis. Obesity, genetic predisposition, bariatric surgery, and allergic conditions represent key modifiable and non-modifiable risk factors. These findings support implementing routine ETDQ-7 screening in primary care and targeted interventions for high-risk populations.