Longitudinal Association Between Menopausal Transition and Obstructive Sleep Apnea with Effect Modification by Salt...

Background/Objectives: As high salt intake may increase obstructive sleep apnea (OSA) risk through fluid retention and upper airway narrowing during sleep, we aimed to determine whether dietary salt intake modified the association between menopausal transition and the risk of OSA. Methods: Between 2014 and 2018, we conducted a longitudinal study of 2572 women aged 42-52 years at the Kangbuk Samsung Hospital Total Healthcare Center. The participants were followed up until the end of 2024. OSA risk was evaluated using the STOP-Bang questionnaire, with a body mass index threshold adjusted to ≥30 kg/m² in accordance with a Korean validation study. Dietary salt intake was categorized into tertiles, with tertile 3 representing the highest salt intake. Generalized estimating equations with time-dependent covariates were used to account for repeated measurements over time. Results: OSA risk increased during menopausal transition. Compared with the pre-menopausal stage, both late transition (β = 0.41, 95% confidence interval [CI] 0.05-0.78) and post-menopause (β = 0.61, 95% CI 0.20-1.02) were significantly associated with an increased risk of OSA, independent of potential confounders. A high salt intake (tertile 3) was also significantly associated with OSA. A significant interaction was observed between menopausal transition and salt intake (p = 0.040), with a stronger association between menopausal transition and OSA during the early transition stage in women with higher salt intake. Conclusions: Menopausal transition and high dietary salt intake appear to act synergistically to increase the risk of OSA in middle-aged women. Our results suggest that implementing targeted screening and reducing dietary salt intake may mitigate the risk of OSA during menopausal transition.