Effectiveness of CPAP treatment in daytime function in sleep apnea syndrome - A randomized controlled study with an optimized placebo

Application of continuous positive airway pressure (CPAP) as the standard t reatment for sleep apnea/hypopnea syndrome (SAHS) is a moot point. Studies on the effectiveness of this treatment have been challenged because of the lack of a suitable placebo. The recent description of a true placebo (sham CPAP) prompted us to conduct a randomized trial of CPAP or placebo to asses s the effectiveness of CPAP in improving SAHS-related symptoms and daytime function in patients with moderate to severe SAHS. Forty-eight patients, st ratified in four groups according to severity, were randomly allocated into two treatment groups (optimal and sham CPAP) for a 6-wk period. Of these, 45 completed follow-up 91% males; age: 54 +/- 10 yr; body mass index [BMI]: 32 +/- 6 kg/m(2); apnea-hypopnea index [AHI]: 54 +/- 19 events/h; and Epwo rth Sleepiness Scale [ESS]: 16 +/- 5). The ESS, a questionnaire on SAHS-rel ated symptoms, Functional Outcomes Sleep Questionnaire (FOSQ), and the Shor t Form Health Survey (SF-36) were completed at inclusion and after treatmen t. After 10 d of washout, the placebo group was treated with optimal CPAP a nd reassessed before and after optimal CPAP. The group receiving optimal CP AP when compared with the group with sham CPAP showed considerably greater improvement in the relief of sleepiness (-9.5 versus -2.3, p < 0.001), othe r SAHS-related symptoms (-18.5 versus -4.5, p < 0.001), vigilance (+8.5 ver sus +3.4, p = 0.009), and general productivity (+4.0 versus +0.5, p = 0.04) FOSQ scales. Both groups used a similar number of hours for the optimal an d the sham CPAP (4.3 versus 4.5, (p = NS). The patients initially treated w ith placebo CPAP improved significantly more when optimal CPAP was applied for ESS (-2.3 versus -6.7, p < 0.001) and other sleep apnea syndrome (SAS)- related symptoms (-4.5 versus -11.2, p = 0.02). Our study provides strong e vidence of the effectiveness of CPAP treatment In improving symptoms and pe rceived health status in moderate to severe SAHS.