Factors influencing the response of psychological symptoms to continuous positive airway pressure therapy

To examine whether in obstructive sleep apnea (OSA) patients the degree of sleepiness, slow-wave sleep (SWS) loss, and hypoxia influence the response of psychological symptoms to continuous positive airway pressure (CPAP) therapy. A prospectively planned cohort was assessed. Participants underwent full overnight polysomnography. All answered the Symptom Checklist-90-Revised (SCL-90) and the Epworth sleepiness scale (ESS). Only cases with an apnea-hypopnea index a parts per thousand currency sign60 events/h were 24 invited to participate. In an interview by telephone, after a follow-up period between 2 months and 1 year, patients informed whether they were in treatment with CPAP or remained voluntarily untreated. Subjects who accepted to participate answered for the second time the SCL-90 and the ESS. The baseline variables of interest were: (a) score of the ESS, (b) duration of SWS, and (c) time with arterial oxygen saturation below 90 %. The outcomes were the change in SCL-90 scores in all dimensions and indices of the questionnaire. A number of 73 patients, mostly men, were included. In uncontrolled analyses, CPAP-treated patients showed significant improvement at follow-up in 10 of the 13 SCL-90 scores. Comparing with the control group, only six scores were improved. Baseline sleepiness was the best predictor of SCL-90 improvement after CPAP treatment in the univariate analyses, and the only significant predictor of improvement in a multivariate regression model. Sleepiness may supersede other factors that influence psychological improvement in CPAP-treated patients with severe OSA.