The implication of sleep position in the evaluation of surgical outcomes in obstructive sleep apnea

OBJECTIVE: To investigate the effect of sleep position on surgical outcomes in obstructive sleep apnea (OSA). STUDY DESIGN: Retrospective review of 69 consecutive patients. SUBJECTS AND METHODS: Preoperative and postoperative polysomnographic data and Epworth sleepiness scale were obtained. Patients were categorized into success, response, no response. and failure groups according to apnea-hypopnea index (AHI) after uvulopalatopharyngoplasty. Proportions of supine or lateral position and AHI of each position were evaluated. Positioncorrected AHI was developed in order to eliminate the effect of sleep position. RESULTS: Preoperative proportion of supine position in the failure group (n = 26) was 41.3 percent, which was the lowest among four groups (P = 0.010), and increased to 60.8 percent postoperatively (P = 0.028). Twenty-two (84.6%) among the failure group had supine position dependency. Regrouped by position-corrected AHI 15 patients moved into different groups. Postoperative AHI showed positive correlation with increased supine position when BMI was controlled (r = 0.515, P = 0.006). CONCLUSION: Without appropriate correction based on the change of sleep position, the fluctuation of sleep position in each polysomnography might confound surgical Outcomes ill OSA patients. Thus, it is a substantial issue how to control or reflect the positional effect on AHI when treatment results are evaluated.