Study objectives: Poor adherence to continuous positive airway pressure (CPAP) commonly affects therapeutic response in obstructive sleep apnea (OSA). We aimed to determine predictors of adherence to CPAP among participants of the Sleep Apnea and cardioVascular Endpoints (SAVE) trial.
Methods: SAVE was an international, randomized, open trial of CPAP plus usual care versus usual care (UC) alone in participants (45-75 years) with co-occurring moderate-to-severe OSA (≥12 episodes/h of ≥4% oxygen desaturation) and established cardiovascular (CV) disease. Baseline sociodemographic, health and lifestyle factors, OSA symptoms, and 1-month change in daytime sleepiness, as well as CPAP side effects and adherence (during sham screening, titration week, and in the first month), were entered in univariate linear regression analyses to identify predictors of CPAP adherence at 24 months. Variables with p <0.2 were assessed for inclusion in a multivariate linear mixed model with country, age, and sex included a priori and site as a random effect.
Results: Significant univariate predictors of adherence at 24 months in 1,121 participants included: early adherence measures, improvement in daytime sleepiness at 1 month, fixed CPAP pressure, some measures of OSA severity, cardiovascular disease history, breathing pauses, and very loud snoring. While observed adherence varied between countries, adherence during sham screening, initial titration, and the first month of treatment retained independent predictive value in the multivariate model along with fixed CPAP pressure and very loud snoring.
Conclusions: Early CPAP adherence had the greatest predictive value for identifying those at highest risk of non-adherence to long-term CPAP therapy.
Clinical trial registration: SAVE is registered with clinicaltrials.gov (NCT00738179).
Keywords: continuous positive airway pressure; obstructive; patient compliance; sleep apnea.
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