Beyond the apnea-hypopnea index: The predictive value of oxygen desaturation parameters for metabolic syndrome in OSA

The Apnea-Hypopnea Index (AHI) often correlates poorly with clinical comorbidities in Obstructive Sleep Apnea (OSA). We aimed to investigate whether one of three oxygen desaturation metrics during sleep is more or less predictive than the conventional AHI for the metabolic syndrome (MetS).

This prospective, cross-sectional study analyzed 120 consecutive patients with OSA (AHI ≥5 events/h). MetS was diagnosed based on International Diabetes Federation (IDF) criteria. Polysomnographic parameters (AHI, T90, nadir SpO₂, mean SpO₂) were compared between patients with and without MetS. Multivariate logistic regression identified independent predictors, controlling for age, gender, BMI, and cardiovascular history.

Among the variables tested in the univariate analysis, only gender and AHI showed no significant correlation with MetS. Most variables (age, BMI, ESS score, CVD history, T90) showed significant positive correlations, while nadir and mean SpO₂ showed significant negative correlations. In the multivariate analysis, a positive history of cardiovascular disease was the only independent predictor (OR: 7.11; p < 0.001). Compared to the univariate analysis, the three oxygen desaturation metrics (T90, mean SpO₂, and nadir SpO₂) lost significance.

Although the study set was confined to patients with OSA, none of the oxygen desaturation metrics and certainly not AHI showed predictive value for MetS. Although MetS frequently occurs in patients with OSA, the main predictors remain a positive history of CVD and BMI above normal.