Evaluation of sham-CPAP as a placebo in CPAP intervention studies.
OBJECTIVE
To evaluate the use of sham-continuous positive airway pressure (CPAP) treatment as a placebo intervention.


METHODS
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).


METHODS
The first 104 CATNAP participants randomized to the sham-CPAP intervention arm.


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.


CONCLUSIONS
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.


BACKGROUND
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.
Rodway
George W
GW
University of Utah College of Nursing and School of Medicine, Salt Lake City, UT, USA.
Weaver
Terri E
TE
Mancini
Cristina
C
Cater
Jacqueline
J
Maislin
Greg
G
Staley
Bethany
B
Ferguson
Kathleen A
KA
George
Charles F P
CF
Schulman
David A
DA
Greenberg
Harly
H
Rapoport
David M
DM
Walsleben
Joyce A
JA
Lee-Chiong
Teofilo
T
Kuna
Samuel T
ST
D000328:Adult; D000368:Aged; D045422:Continuous Positive Airway Pressure / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D012894:Sleep Stages
D010919:Placebos