Adherence and Subthreshold Adherence in Sleep Apnea Subjects Receiving Positive Airway Pressure Therapy: A Retrospective Study Evaluating Differences in Adherence Versus Use.

BACKGROUND: Research on subthreshold compliance with positive airway pressure (PAP) therapy in sleep apnea patients may inform clinical sleep medicine practice. We retrospectively assessed compliant and subthreshold compliant sleep apnea subjects to test whether regular but fewer hours of PAP use would demonstrate clinically meaningful improvements and correlate with outcomes. METHODS: A chart review was conducted of 113 consecutive sleep apnea subjects, naive to treatment, who completed a titration study and filled a PAP therapy prescription. Objective data categorized subjects into 3 groups: compliant, subthreshold compliant, and minimal use. Outcome measures assessed changes in insomnia, sleepiness, and nocturia on average 7 months from PAP initiation. Correlation coefficients analyzed dose-response relationships between hours of use and changes in outcomes. RESULTS: Among 113 PAP attempters, 104 (92%) were current users. Among 93 users with objective data, regular (consistent) PAP users included 59 compliant and 21 subthreshold compliant, and 13 subjects were minimal users. Compliant users averaging 6.6 ± 1.3 h/night and 42.0 ± 12.1 h/week showed the largest outcome improvements (all P < .05) with moderate to large effects for insomnia (d = 0.94), sleepiness (d = 0.58), and nocturia (d = 0.56). Subthreshold users averaging 4.1 ± 0.7 h/night but only 18.0 ± 5.6 h/week showed a large effect for insomnia (d = 0.76, P = .03) and nonsignificant, small effects for sleepiness (d = 0.38) and nocturia (d = 0.22). Correlation coefficients showed a trend for decrease in insomnia (P = .08; r = .20) and a significant decrease in nocturia (P = .034; r = 0.25), each in association with hours of PAP use. CONCLUSIONS: In a clinical sample, 86% of sleep apnea subjects regularly used PAP, but adherence was 63%. Regular users showed clinical treatment effects and potential dose-response relationships, suggesting that the term use offers advantages over the term adherence. Currently, subthreshold compliance may not merit insurance coverage in many countries, an issue affecting many sleep apnea patients. [ABSTRACT FROM AUTHOR]