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 (SaO2) and Nadir SaO2, 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, SaO2, and Nadir SaO2 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 SaO2. A statistically significant negative correlation (r2 = 0.424; p < 0.001) was found between the BMI index and the Nadir SaO2.

CONCLUSIONS

Higher BMI values were correlated with lower Nadir SaO2 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.