Patients with positional versus nonpositional obstructive sleep apnea: a retrospective study of risk factors associated with apnea-hypopnea severity

ObjectiveThe aim of this study was to investigate the differences in and risk factors for positional and nonpositional obstructive sleep apnea (OSA).Study designOne hundred twenty-three nonpositional (supine apnea-hypopnea index [AHI] < 2 times the lateral AHI), 218 positional (supine AHI ≥ 2 times the lateral AHI), and 109 age-, gender-, and BMI-matched patients with positional OSA performed 2 nights of sleep study. Gender, age, BMI, and percentage of time in supine position, and percentage of time snoring louder than 40 dB were evaluated as risk factors.ResultsBoth unmatched positional and matched positional patients had less severe overall AHI values, higher mean SpO2, lower percentage time SpO2 less than 90%, and lower percentage of time snoring when compared with the nonpositional group. Overall AHI scores were associated with increasing age and percentage of time snoring for positional and nonpositional groups. However, BMIs were associated with the overall AHI only in the nonpositional group.ConclusionThe influence of position on OSA severity may contribute to the choice and prognosis of treatment and may represent 2 distinct groups with probable anatomic differences.