Correlation between body mass index and obstructive sleep apnea severity indexes — A retrospective study

Purpose: To evaluate if Body Mass Index (BMI) is correlated to Apnea-Hypopnea Index (AHI), mean arterial oxygen saturation (SaO(2)) and Nadir SaO(2), which are all indexes defining the severity of the respiratory stress associated with Obstructive Sleep Apnea (OSA).Materials and methods: Seventy-five adult patients (mean age 51.4) referred for polysomnography were retrospectively recruited. BMI was calculated for each patient, as well as AHI, SaO(2), and Nadir SaO(2) recorded during polysomnography. Spearman's Rho test was used to evaluate if OSA severity was correlated to BMI values. First type error was set as p < 0.025.Results: No correlation was observed between BMI and AHI, and between BMI and SaO(2). A statistically significant negative correlation (r(2) = 0.424; p < 0.001) was found between the BMI index and the Nadir SaO(2).Conclusions: Higher BMI values were correlated with lower Nadir SaO(2) during overnight polysomnography. Since hypoxia stress is a risk factor for cardiovascular diseases and alters the lipid metabolism, dietary consulting should be recommended in association with other treatment modalities for OSA.