Relationship between hours of CPAP use and achieving normal levels of sleepiness and daily functioning.

TLDR: It is suggested that a greater percentage of patients will achieve normal functioning with longer nightly CPAP durations, but what constitutes adequate use varies between different outcomes.

Abstract: CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP) CURRENTLY IS CONSIDERED THE MOST EFFECTIVE TREATMENT FOR OBSTRUCTIVE SLEEP APNEA (OSA) THIS device provides a pneumatic splint to prevent nocturnal airway collapse In randomized clinical trials that included use of sham CPAP as a placebo, treatment with this device has been shown to produce improvements in symptoms, quality of life, sleepiness, neuropsychological performance, and hypertension1 It has also been established that optimal effectiveness depends on consistent use Skipping even 1 night of treatment reverses improvements in daytime sleepiness, response performance, and the physiologic measure of disease severity, the apnea-hypopnea index (AHI)2–4 Although these benefits have been shown in randomized clinical trials, there is considerable variation in use of CPAP by patients in routine clinical practice,5–8 with approximately half using it consistently every night on average 6 hours per night and the other half skipping from 1 to 7 nights per week using it on average 35 hours per night5 It is not known, however, what the impact of differential use of CPAP is on effectiveness of therapy in routine clinical practice It may be that individuals with shorter hours of use are, in general, less well treated with respect to improvements in outcomes such as sleepiness, than are those with longer durations of use Alternatively, there might be individual variation in need for CPAP so that, even though some individuals have shorter hours of CPAP use, they are effectively treated with respect to sleepiness This individual variation might be mediated by biologic mechanisms similar to those of the recently described individual variation in response to sleep deprivation9 To address this question, we conducted a multisite effectiveness study in which we evaluated clinical status outcomes before and after 3 months of routine clinical care that included measurement of CPAP adherence during the entire follow-up period This multisite international study capitalized on patient heterogeneity with regard to average nightly use of CPAP, in order to estimate relationships between the likelihood of achieving a “normal” value on salient clinical measures of sleepiness and functional status and the “dose” of CPAP treatment received (ie, hours of CPAP use per night) Because there is no consensus regarding which outcomes are primary with regard to the assessment of CPAP treatment response, we chose those deemed most applicable to the clinical management of OSA—subjective sleepiness (Epworth Sleepiness Scale [ESS]10), physiologic sleepiness (Multiple Sleep Latency Test [MSLT]11), and disease-specific functional status (Functional Outcomes of Sleep Questionnaire [FOSQ]12) By evaluating the nightly duration of CPAP relative to obtaining normal values in those impaired on each of these measures, we provide data that the clinician can employ in determining optimal treatment response within the context of treatment goals, eg, to reduce daytime sleepiness, improve daily functioning, or both