Thikriat Al-Jewair BDS, MSc, FRCD (C)
Continuous positive airway pressure (CPAP) is effective in the treatment of adult obstructive sleep apnea-hypopnea syndrome (OSAHS) in patients with moderate to severe symptoms, while dental devices may be effective in patients with moderate symptoms.
In adults diagnosed with OSAHS, what is the effect of CPAP in comparison to usual care, oral placebo, sham CPAP, and dental devices on daytime sleepiness measured by subjective and objective sleepiness tests?
The authors performed a comprehensive search of databases, including gray literature, looking for articles that were published before November 2006. One author extracted the data, which the other then checked. They also included data from a previous SR. The inclusion criteria were adults diagnosed by nocturnal polysomnograms (PSG) as having OSAHS of different severities and treated with fixed or auto-titrating CPAP for at least 1 week. The comparators were controls (i.e., usual care, oral placebo, or sham CPAP) and dental devices. The authors only considered parallel or crossover randomized controlled trials (RCTs). They looked for primary outcomes of subjective sleepiness using the Epworth sleepiness scale [ESS], and objective sleepiness using the maintenance of wakefulness test [MWT] and multiple sleep latency test [MSLT]. Secondary outcomes were blood pressure, cardiovascular events, accidents, psychological and cognitive performance, health-related quality of life and adverse events. They excluded studies that measured different outcomes or involved patients who had central nervous system dysfunction. Allocation concealment and blinding (where possible) were the main quality assessment criteria. To compare groups, the authors used mean differences (MD) at endpoint/change for all outcomes. They performed meta-analyses using random effect models to compare the effects of CPAP to the controls and the dental devices groups. They used subgroup analyses stratified by symptom [assessed by ESS] and disease severity (apnea/hypopnea index or oxygen saturation rate) at baseline to investigate heterogeneity. For all included outcomes, the authors ran sensitivity analyses.
This SR included 28 RCTs (13 new studies since the last SR) comparing CPAP with controls or dental devices . A total of 1,989 participants were included. The mean age ranges at baseline were 44-58 years old with the majority of participants being overweight males. The treatment duration ranged from 2 to 24 weeks with the majority of the studies being less than eight weeks. Twenty-three studies assessed subjective sleepiness comparing CPAP to sham CPAP, usual care, or oral placebo, and stratified by symptoms and other clinical and methodological characteristics. Significant improvement in subjective sleepiness with CPAP was observed among all symptom severity levels, but the MD was greatest for the moderate and severe groups, although significant heterogeneity was present in the data. Six trials compared CPAP to dental devices in participants having moderate baseline ESS and found no significant differences (MD -0.9, 95 percent Confidence Interval [CI]: -2.1, 0.4). Seven trials assessed objective sleepiness using MWT, with five of those trials comparing CPAP with controls (MD 3.3 min, 95 percent CI: 1.3, 5.3 in favor of CPAP) and two trials comparing CPAP with dental devices showing no significant differences (MD 0.7 min, 95 percent CI: -1.6, 2.9). Seven trials comparing CPAP with controls assessed objective sleepiness using MSLT and favored CPAP only in the severe disease subgroup. Fifteen trials that compared CPAP to usual care/placebo and one that compared CPAP to dental devices assessed daytime and nighttime blood pressure. Those trials reported inconsistent findings.
CPAP is effective in the treatment of OSAHS in patients with moderate to severe symptoms. Dental devices may be effective in relieving moderate symptoms.
Source of Funding:
The National Institute for Health Research (NIHR) Health Technology Assessment Programme and commissioned on behalf of National Institute for Health and Clinical Excellence (NICE).
Importance and Context:
CPAP has been considered the gold standard in the treatment of OSAHS. Evidence, however, is limited on the effects of CPAP across different symptom severities. Further, evidence is needed to evaluate the CPAP effectiveness compared to other treatments, like dental devices, to help inform clinical decision and policy making.
Strengths and Weaknesses of the Systematic Review:
The authors of this SR executed a comprehensive search strategy with adequate inclusion and exclusion criteria. They also strengthened the review by restricting it to randomized controlled trials (both parallel group and crossover) and evaluating both subjective and objective outcomes. The authors performed meta-analyses when appropriate, confirmed results with sensitivity analyses according to study design, and presented the results in a stratified manner according to baseline symptoms and disease severity, which explained heterogeneity. One weakness is the authors made the assumption that all CPAP modifications will produce consistent results. In addition, they treated all outcome measurements similarly, without assessing or considering the reliability and accuracy of the outcome measurement. The authors did not assess the potential for publication bias.
Strengths and Weaknesses of the Evidence:
The review assessed high quality evidence from RCTs comparing CPAP to controls or dental devices. Strong evidence confirmed effectiveness of CPAP compared to controls in moderate to severe symptoms. Fourteen of the RCTs were of crossover designs and did not describe the duration of washout periods; however, the effect of CPAP on daytime sleepiness is thought to be short-lived and not at high risk for carryover effects. Few studies evaluated patients with mild ESS symptoms; therefore, results from this patient group remain inconclusive despite consistent findings to date. Although blinding was a quality assessment criterion, it was only optimally fulfilled by a sham CPAP control group. Stratification was undertaken to control heterogeneity; however, significant heterogeneity was still noted in most of the studies reflecting the inherent differences in methodology and clinical conditions among the trials. Middle-aged males were overrepresented in all trials; therefore, the results cannot be generalized to other genders or age groups.
Implications for Dental Practice:
This review showed that CPAP is more effective than control interventions in patients with moderate and severe OSAHS symptoms. Although it could not provide sufficient evidence on treatment of milder OSAHS cases, a recent RCT (1) evaluated the efficacy of CPAP in treating mild-to-moderate OSAHS, and reported significant improvements for those patients as well. When CPAP was compared to dental devices, it showed similar effects in patients with moderate symptoms. Another RCT (2) that compared CPAP with dental devices reported similar findings after one month of treatment in patients with moderate and severe symptoms. The severity of the OSAHS condition is important in guiding the dentist's decision on which treatment modality to recommend. Likewise, the dentist should consider the treatment’s long-term effectiveness, documented compliance rates, risks and benefits, and cost to the patient. References: 1. Weaver TE, Mancini C, Maislin G, et al. Continuous positive airway pressure treatment of sleepy patients with milder obstructive sleep apnea: results of the CPAP Apnea Trial North American Program (CATNAP) randomized clinical trial. Am J Respir Crit Care Med 2012;186(7):677-83. 2. Phillips CL, Grunstein RR, Darendeliler MA, et al. Health outcomes of continuous positive airway pressure versus oral appliance treatment for obstructive sleep apnea. Am J Respir Crit Care Med 2013;187(8):879-87.