Residual daytime sleepiness (RES) in CPAP-treated obstructive sleep apnea (OSA) patients in the European Sleep Apnea Database (ESADA)

In patients with OSA treated with continuous positive airway pressure (CPAP), the prevalence and predictive factors of RES were investigated. Excessive daytime sleepiness (EDS) at baseline and RES were defined as an Epworth Sleepiness Scale (ESS) score >10. Anthropometrics, OSA severity at baseline, subjective sleep time at the first follow-up visit (V1), CPAP adherence (< or ≥4 h), and residual AHI (<10/h or ≥10/h) were evaluated with regard to RES. Median follow-up at V1 was 51 months (range 49- 66). In all patients with V1 (n=5549), EDS prevalence decreased from 49.7% to 20.8%. In patients with sleep data at V1 (n=2349, baseline age 55.2±11.9 (SD) yrs, BMI 33.4±6.9 kg/m2, AHI: 39.2±23.0 events/h), EDS prevalence decreased from 54.0% to 35.5%. Stratification according to CPAP use and residual AHI showed no differences between patients with and without RES. The relationship between baseline ESS and change in EDS (ΔESS) at V1 was less steep in patients with RES (ΔESS: -5.7+0.41•ESS; R2= 0.31) than in patients without RES (ΔESS: -3.4+0.77•ESS; R2=0.63). Multivariate linear regression identified some predictors of ESS at V1, but explained a minimal fraction of variance (R2: 0.055): male sex (β: 0.66), age (β: -0.29), BMI at baseline ((β: 0.09), subjective sleep time (β: -0.007), and residual AHI (β: 0.06). No comorbidity (coronary artery disease, diabetes, hypertension, psychiatric disorders, COPD, and insomnia) significantly predicted RES. In conclusion, RES occurs in about one fifth of OSA patients on long-term CPAP and its predictors were similar to those identified in short-term studies.