[The clinical and polysomnographic differences between obese and non-obese patients with obstructive sleep apnea]

Obesity has been considered to be one of the important risk factor for obstructive sleep apnea (OSA). We aimed to investigate the clinical and polysomnographic differences of obese and non-obese OSA patients and how these differences, if any, can be reflected in our daily clinical practice.

The polysomnographic data of 157 consecutive patients that underwent a sleep study were analyzed. Ninety-nine adult patients with a diagnosis of OSA [apnea-hypopnea index (AHI) ≥ 5/hour] were retrospectively assesed in two groups in respect of obese (BMI ≥ 30 kg/m2) or non-obese (BMI <30 kg/m2) according to body mass index (BMI). The clinical and polysomnographic results of the patients in both groups were compared.

Between 2010 and 2011, 99 (31 K/68 M) of 157 patients underwent polysomnography were diagnosed with OSA (AHI ≥ 5/hour). Thirthy six patients with OSA (36.4%) were non-obese and 63 patients (63.6%) were obese. There were no differences in the symptoms related to OSA between two groups (p> 0.05). Although there was no statistical significance, the age of the obese patients (50.5 ± 12.7 years) was lower than those of the non-obese (54.9 ± 10.0 years) in polysomnography their total sleep time was shorter and sleep latency later, and sleep efficiency, arousal index, N3%, and REM% were lower and N1% was higher (p> 0.05). While in the obese OSA patients the AHI and Epworth Sleepiness sclae were higher (respectively; p= 0.028, p= 0.01), average oxygen saturation at sleep was lower (p<0.001). While obese OSA patients had similar ratio of hypertension and atherosclerotic heart disease with non-obese OSA patients, whereas diabetes mellitus was higher in obese OSA group (p= 0.036). The use of antidepressant drug was more common in the non-obese patients than the obese patients (p= 0.011).

Although obese OSA patients have a more severe disease compared to nonobese OSA patients, there were no significant differences in clinical and polysomnographics findings between two groups. Should be noted that OSA may occur in non-obese patients.