Predictors of residual sleepiness in patients with obstructive sleep apnea syndrome on continuous positive airway pressure

Context Excessive daytime sleepiness is a common symptom of obstructive sleep apnea, which improves with the application of the continuous positive airway pressure (CPAP). However, it is not unusual that some patients continue to complain of residual excessive sleepiness (RES). Aims We aimed in this study to evaluate the predictors of residual sleepiness in these patients. Settings and design This is a retrospective study done in a tertiary center, and data for the years 2010-2015 were collected. Materials and methods The inclusion of patients with obstructive sleep apnea syndrome and compliant on CPAP was done. We included the pretreatment apnea-hypopnea index and epworth sleepiness scale (ESS) in addition to the CPAP using parameters. Comparison between the compliant obstructive sleep apnea syndrome with RES and without RES was done. Statistical analysis Wecompared between the patients with RES and without. Regression analysis was used to detect the predictors for RES. Results The mean age of the compliant patients with RES was significantly younger than compliant patients without RES (54.15 +/- 10.1 vs. 59.23 +/- 10.7; P=0.001). All the patients used the CPAP adequately (>= 4 h per night for >= 70% of the nights); the patients with RES used the CPAP significantly lower than the patients without RES. As for the predictors for residual sleepiness on CPAP for those patients, we found that the pretreatment ESS was a predictor as well as the CPAP-use parameters. Conclusion Residual excessive daytime sleepiness is common in compliant patients with obstructive sleep apnea syndrome on CPAP, and the predictors for the occurrence of residual sleepiness on CPAP are younger age, higher baseline ESS, and lower CPAP usage percent.