Evaluation of sham-CPAP as a placebo in CPAP intervention studies

George W Rodway, Terri E. Weaver, Cristina Mancini, Jacqueline Cater, Greg Maislin, Bethany Staley, Kathleen A. Ferguson, Charles F P George, David A. Schulman, Harly Greenberg, David M. Rapoport, Joyce A. Walsleben, Teofilo Lee-Chiong, Samuel T. Kuna

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Study Objectives: To evaluate the use of sham-continuous positive airway pressure (CPAP) treatment as a placebo intervention. Design and Setting: Analysis of polysomnograms performed in fixed order without sham-CPAP and on the first night of the sham-CPAP intervention in participants in the CPAP Apnea Trial North American Program (CATNAP), a randomized, placebo controlled trial evaluating the effects of CPAP treatment on daytime function in adults with newly diagnosed mild to moderate obstructive sleep apnea (apnea hypopnea index (AHI) 5 - 30). Participants: The first 104 CATNAP participants randomized to the sham-CPAP intervention arm. Measurements and Results: Compared to the polysomnographic measures without sham-CPAP, the study on the first night with sham-CPAP had statistically significant differences that suggested a decrease in sleep quality: decreased sleep efficiency, increased arousal index, increased time in stage 1 NREM sleep, and prolonged latency to REM sleep. However, all of these differences had a relatively small effect size. Compared to the polysomnogram without sham-CPAP, the number of hypopneas on the sham-CPAP polysomnogram was significantly increased and the number of apneas significantly decreased. Relatively minor differences in AHI with and without sham-CPAP were present and were dependent on the criteria used to score hypopneas. Conclusion: Comparison of polysomnograms with and without sham-CPAP revealed differences that, although statistically significant, were small in magnitude and had relatively low effect sizes suggesting minimal clinical significance. The results support the use of sham-CPAP as a placebo intervention in trials evaluating the effects of CPAP treatment in patients with obstructive sleep apnea. Clinical Trial Information: This paper was a secondary analysis of clinical trial data. CATNAP: CPAP Apnea Trial North American Program, the trial from which the data were obtained, is registered with clinicaltrial.gov. Registration #NCT00089752.

Original languageEnglish (US)
Pages (from-to)260-266
Number of pages7
Issue number2
StatePublished - Feb 1 2010
Externally publishedYes


  • CPAP
  • Placebo
  • Polysomnogram
  • Randomized controlled trial
  • Sham-CPAP

ASJC Scopus subject areas

  • Physiology (medical)
  • Clinical Neurology


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