A comparative study on the clinical and polysomnographic pattern of obstructive sleep apnea among obese and non-obese subjects

OBJECTIVE: This study was designed to compare the pattern of obstructive sleep apnea (OSA) among obese and nonobese subjects regarding clinical and polysomnographic data obtained for a polysomnographic study. METHODS: A cross-sectional retrospective descriptive study was conducted by analyzing polysomnographic data in 112 consecutive patients underwent a sleep study at our sleep laboratory from January 2009 to July 2010. Out of them, 81 were diagnosed to have OSA (apnea-hypopnoea Index ≥5). These patients were classified in two groups with body mass index (BMI) < 27.5 kg/m(2) as nonobese and BMI≥27.5 kg/m(2) as obese. Clinical as well as polysomnographic data were evaluated and compared between the two groups. Patients were also evaluated for other risk factors such as smoking, alcoholism, and use of sedatives. Data were subjected to statistical analysis (χ(2)-test, P value <0.05 considered to be significant). The Fisher Exact test was applied wherever the expected frequency for a variable was ≤5. RESULTS: Of 81 patients with OSA, 36 (44.4%) were nonobese with a mean BMI of 26.62 ± 2.29 kg/m(2) and 45 (55.6%) were obese with a mean BMI of 35.14 ± 3.74 kg/m(2). Mean AHI per hour was significantly more in the obese than in the nonobese group (50.09 ± 29.49 vs. 24.36 ± 12.17, P<0.001). The use of one or more sedatives was more in nonobese as compared to obese (58.3% vs. 24.4%, P=0.002). The obese group had significantly higher desaturation and arousal index (P<</i>0.001). The minimal oxygen saturation was lower in the obese than the nonobese group (68.5 ± 13.00 vs. 80.3 ± 7.40, P<</i>0.001) and was well below 90% in both groups. Overall, the OSA in nonobese patients was mild-to-moderate as compared to that of the obese and no significant differences were observed between them as regard to age, gender, mean neck circumference, excessive daytime sleepiness, adenoid or tonsillar enlargement, smoking, and remaining polysomnographic parameters. CONCLUSION: Obstructive sleep apnea can occur in nonobese persons though with less severity as compared to obese leading to a concept that OSA is not restricted to obese persons only and there is a high demand of its awareness regarding evaluation, diagnosis, and management in such individuals.