Excessive daytime sleepiness in obstructive sleep apnea (OSA) patients treated with continuous positive airway pressure (CPAP): data from the European Sleep Apnea Database (ESADA)

Excessive daytime sleepiness (EDS) is a frequent symptom of obstructive sleep apnea (OSA) which usually improves or disappears under treatment with nasal continuous positive airway pressure (CPAP). However, in some patients sleepiness persists despite CPAP treatment. Few studies have examined the issue of persistent daytime sleepiness in CPAP-treated OSA patients. We retrospectively analyzed data regarding subjective residual sleepiness, assessed as an Epworth Sleepiness Scale score (ESS) >10, in patients from the European Sleep Apnea Database (ESADA) cohort at baseline (n=4853, mean age±SD 54.8±11.8 years, 26.1% females) and at the first visit after a median follow-up of 5 months (IQR 3-13) . An ESS >10 was reported by 56% of patients at baseline, and by 28.2% of patients at follow-up. Residual sleepiness was further analyzed in a subgroup of patients (n=2190, age: 55.1±12.0 years, 26.1% females) with data on residual OSA and CPAP adherence and a median follow-up duration of 3 months (IQR 1-15). In this sample, 69% of the patients underwent sleep studies during CPAP use; an ESS >10 was reported by 54% of patients at baseline, and by 35.7% at follow-up. Residual OSA, defined as an apnea-hypopnea index (AHI)>10/h , and insufficient CPAP adherence, defined as nightly use < 4 h, occurred with similar frequency in both patients with and without sleepiness at follow-up. Prevalence of residual sleepiness was highest (40%) in patients with short follow-up duration (0-3 months), then the prevalence of EDS remained stable at 13-19% in patients with first follow-up visit between 4 months and >=2 years. The change in ESS (n=2190) was weakly correlated with the hours of CPAP nightly use (r = 0.15, p<0.0001). Logistic regression showed that an ESS score>10 at follow-up was associated directly with ESS at baseline, and indirectly with AHI at baseline, duration of follow-up, nightlyl CPAP use, subjective sleep duration at follow-up (R2 of the model: 0.402). Analysis of residual EDS in different European countries showed some heterogeneity both at baseline and at first follow-up visit, suggesting some effects of cultural and lifestyle factors. In conclusion, EDS in CPAP-treated OSA patients was found in about one in four patients at follow-up, with a 40% prevalence in the first 3 months of CPAP treatment, which halved after longer follow-up. The finding of sleepiness during effective CPAP treatment with good CPAP adherence in a significant percentage of the patients suggests that wake-promoting agents may be useful, but patients should be evaluated after at least 3 months of CPAP treatment.