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Continuous Positive Airway Pressure to Improve Milder Obstructive Sleep Apnea

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: August 12, 2004
Last updated: May 22, 2009
Last verified: May 2009
The purpose of this study is to determine whether functional status improves in individuals with milder obstructive sleep apnea (OSA) following continuous positive airway pressure (CPAP) treatment.

Condition Intervention
Lung Diseases Sleep Apnea Syndromes Hypertension Device: Continuous Positive Airway Pressure (CPAP) Device: Sham CPAP device

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Investigator)
Primary Purpose: Treatment
Official Title: Impact of CPAP on Functional Outcomes in Milder Obstructive Sleep Apnea (CATNAP)

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Primary Outcome Measures:
  • Change in functional status [ Time Frame: Measured by the Functional Outcomes of Sleep Questionnaire at Week 8 ]

Secondary Outcome Measures:
  • Improvement in daytime sleepiness [ Time Frame: Measured at Week 8 ]
  • Reduction in nocturnal blood pressure [ Time Frame: Measured at Week 8 ]
  • Mood, as measured by the Profile of Mood States [ Time Frame: Measured at Week 8 ]

Estimated Enrollment: 272
Study Start Date: September 2003
Study Completion Date: November 2008
Primary Completion Date: August 2008 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: 1
CPAP device
Device: Continuous Positive Airway Pressure (CPAP)
CPAP device used at night
Placebo Comparator: 2
Sham CPAP device
Device: Sham CPAP device
Sham CPAP device used at night

Detailed Description:


OSA is characterized as mild, moderate, or severe, according to the number of respiratory disturbances per hour of sleep (RDI), as defined by the American Academy of Sleep Medicine. CPAP is the primary treatment for sleep apnea. The column of pressure delivered to the upper airway by this device immediately eliminates the respiratory disturbances when it is applied. There is evidence from randomized controlled studies that CPAP also improves functional status, and the key manifestation of OSA, including excessive daytime sleepiness, in individuals with severe OSI (i.e., RDI greater than 30). However, there has been limited research exploring improvement in functional status in individuals with less severe OSA (i.e., those with mild OSA and RDI of 5-15 or moderate OSA and RDI of 16-30). The large placebo effect that has been reported in controlled studies of OSA-associated functional outcomes mandates the need for a placebo in studies evaluating the true impact of this treatment. Results from the three randomized controlled studies in milder OSA that have examined this issue have been equivocal, principally because of serious methodological limitations. It remains unclear whether CPAP treatment improves daily functioning in those with milder OSA (RDI 5-30). This is a critical issue as this level of disease severity represents the largest segment of OSA and comprises 15% of the U.S. population.


Using Granger's model of functional assessment, this study will examine whether functional status improves in participants with milder OSA following CPAP treatment. The study will employ a randomized, placebo-controlled, parallel study design, and will use a sham CPAP device as the placebo in participants with significant daytime sleepiness. The study will test the hypothesis that the change in functional status (measured by the Functional Outcomes of Sleep Questionnaire) after 8 weeks of treatment will be greater for participants treated with active CPAP compared to the placebo. Secondary aims of the study include examining whether CPAP also improves daytime sleepiness, and determining whether CPAP can reduce nocturnal blood pressure to lower the risk for stroke and hypertension linked to OSA.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria

  • Newly diagnosed with OSA on overnight polysomnogram (PSG) with RDI between 5 and 30
  • Score of greater than 11 on the Epworth Sleepiness Scale (ESS) on two administrations of the instrument (performed at prescreening and screening), each completed on a different day to avoid sporadic values and confirm the presence of excessive daytime sleepiness
  • Stable medical history and no change in medications, including hypertension medications, in the 3 months prior to study entry
  • Stable psychiatric history and no change in psychotropic medications in the 3 months prior to study entry
  • Has access to a telephone

Exclusion Criteria

  • Diagnosis of another sleep disorder in addition to OSA based on PSG, e.g., periodic limb movement disorder (greater than 10 limb movements per hour of sleep with arousal); central sleep apnea (greater than 5 or more central apneas); insomnia; sleep hypoventilation syndrome; or narcolepsy
  • Previous treatment for sleep apnea with nasal CPAP, oral appliance, home oxygen therapy, uvulopalatopharyngoplasty, tracheotomy, or other surgery for OSA
  • Oxygen or bi-level CPAP required for treatment of OSA
  • Unable to return for study instructions or follow-up testing
  • Medically unstable condition (e.g., heart attack, congestive heart failure, Cheyne-Stokes breathing, unstable angina, uncontrolled thyroid disease, unstable diabetes, depression or psychosis, ventricular arrhythmias, cirrhosis, or recently diagnosed cancer) in the 3 months prior to study entry
  • Regular use (greater than 3 times per week) of sedative, hypnotic, or alerting medications (such as Modafinil) in the 3 months prior to study entry
  • Chronic nasal congestion that would prevent the use of a nasal mask, in the 3 months prior to study entry
  • History of automobile accidents due to excessive daytime sleepiness
  • Employed in transportation-related safety sensitive occupation such as an airline pilot, truck driver, or train engineer
  • Night shift worker regularly experiencing jet lag, or a history of irregular work schedules in the 6 months prior to study entry
  • Regular use of alcohol as determined by answering yes to one or more of the questions on the CAGE questionnaire (i.e., alcohol dependent)
  • Recent or recurring history of substance abuse leading to tolerance or dependence
  • Pregnant; women must either be postmenopausal or confirmed not pregnant by a urine pregnancy test
  • Unable to perform study tests, e.g., inability to communicate verbally; inability to write and read in English; less than a 5th grade reading level (evaluated using Flesch-Kincaid assessment); visual impairment; hearing impairment; cognitive impairment (e.g., previous head injury); or upper extremity motor deficit (e.g., previous stroke or spinal cord injury)
  • Residing with an individual who is currently using CPAP treatment
  Contacts and Locations
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Please refer to this study by its identifier: NCT00089752

United States, Colorado
National Jewish Medical and Research Center (NJC)
Denver, Colorado, United States, 80206
United States, Georgia
Emory University School of Medicine (EMO)
Atlanta, Georgia, United States, 30329
United States, New York
North Shore-Long Island Jewish Health System (LIJ)
Long Island, New York, United States, 11040
New York University Medical School
New York, New York, United States, 10016
Canada, Ontario
University of Western Ontario (UWO)
London, Ontario, Canada
Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
Study Chair: Terri Weaver University of Pennsylvania
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: NHLBI Identifier: NCT00089752     History of Changes
Other Study ID Numbers: 163
R01HL076101 ( US NIH Grant/Contract Award Number )
Study First Received: August 12, 2004
Last Updated: May 22, 2009

Additional relevant MeSH terms:
Sleep Apnea Syndromes
Sleep Apnea, Obstructive
Lung Diseases
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Signs and Symptoms
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases processed this record on June 23, 2017