Association between Epworth Sleepiness Scores and CPAP compliance in patients with obstructive sleep apnea

Continuous positive airway pressure (CPAP) therapy is the gold standard treatment for obstructive sleep apnea, but adherence remains suboptimal. Subjective symptoms such as excessive daytime sleepiness may influence motivation to maintain therapy. This study examined whether baseline Epworth Sleepiness Scale (ESS) scores predict early CPAP adherence compared with objective measures such as the Apnea-Hypopnea Index (AHI).

We conducted a retrospective observational study of 400 adults with Obstructive Sleep Apnea prescribed CPAP between 2021 and 2023. Thirty days of CPAP adherence data was downloaded and categorized into five ordinal groups ranging from very low to very high adherence. Associations between ESS and adherence were assessed using chi-square tests, Goodman and Kruskal's gamma, and ordinal logistic regression adjusted for AHI, age, sex, and body mass index.

Higher ESS scores were significantly associated with greater adherence (χ² = 28.7, P = 0.026; gamma = 0.199). Ordinal regression showed each 1-point increase predicted 7.4% higher odds of being in a greater adherence category (OR 1.072, 95% CI 1.027-1.117, P < 0.001). Age modestly predicted adherence (OR 1.010, P = 0.019). AHI, body mass index, and sex were not significant predictors. Patients with severe daytime sleepiness had the highest rates of excellent adherence (>90%).

Although causality cannot be inferred from a retrospective design, higher subjective sleepiness, measured by ESS, was associated with higher early adherence. Incorporating ESS into routine evaluation may identify patients at risk for nonadherence and guide targeted interventions.