Diagnosis and Initial Management of Obstructive Sleep Apnea without Polysomnography

A Randomized Validation Study

6 February 2007 | Volume 146 Issue 3 | Pages 157-166

Background: Polysomnography (PSG), despite limited availability and high cost, is currently recommended for diagnosis of obstructive sleep apnea and titration of effective continuous positive airway pressure (CPAP).

Objective: To test the utility of a diagnostic algorithm in conjunction with ambulatory CPAP titration in initial management of obstructive sleep apnea.

Design: A randomized, controlled, open-label trial that compared standard PSG with ambulatory CPAP titration in high-risk patients identified by a diagnostic algorithm.

Setting: A tertiary referral sleep disorders program in Vancouver, British Columbia, Canada.

Patients: 68 patients with a high pretest probability of moderate to severe obstructive sleep apnea (apnea–hypopnea index [AHI] >15 episodes/h) identified by sequential application of the Epworth Sleepiness Scale (ESS) score, Sleep Apnea Clinical Score, and overnight oximetry.

Intervention: Patients were randomly assigned to PSG or ambulatory titration by using a combination of auto-CPAP and overnight oximetry. They were observed for 3 months.

Measurements: Apnea–hypopnea index on CPAP, ESS score, quality of life, and CPAP adherence.

Results: The PSG and ambulatory groups had similar median BMI (38 kg/m²), age (55 years), ESS score (14 points), and respiratory disturbance index (31 episodes of respiratory disturbance/h). Each episode is determined by a computer algorithm based on analysis of oxygen saturation measured by pulse oximetry. After 3 months, there were no differences in the primary outcome, AHI on CPAP (median, 3.2 vs. 2.5; difference, 0.8/h [95% CI, –0.9 to 2.3]) (P = 0.31), between the PSG and ambulatory groups, or in the secondary outcomes, ESS score, Sleep Apnea Quality of Life Index, and CPAP. Adherence to CPAP therapy was better in the ambulatory group than in the PSG group (median, 5.4 vs. 6.0; difference, –1.12 h/night [CI, –2.0 to 0.2]) (P = 0.021).

Conclusions: In the initial management of patients with a high probability of obstructive sleep apnea, PSG confers no advantage over the ambulatory approach in terms of diagnosis and CPAP titration. The ambulatory approach may improve adherence to treatment. When access to PSG is inadequate, the ambulatory approach can be used to expedite management of patients most in need of treatment.

Editors' Notes Context Overnight polysomnography in a sleep laboratory is normal practice for diagnosing obstructive sleep apnea (OSA) but it is expensive and can delay diagnosis. Contribution The authors combined standard clinical scales and overnight home oximetry to ensure a pretest probability of OSA of 90% or greater. Sixty-eight patients were randomly assigned to usual care (polysomnography obtained before continuous positive airway pressure [CPAP]) or ambulatory management (start CPAP without doing polysomnography). After 3 months, the 2 groups had the same results on overnight polysomnography. Cautions The study was done in a single tertiary care center. Implications Most patients with a probability of OSA of 90% or greater do not require polysomnography before starting CPAP. —The Editors

 

Author and Article Information

From University of British Columbia and Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada.

ClinicalTrials.gov identifier: NCT00254059.

Acknowledgments: The authors thank their colleagues, staff, and patients of the University of British Columbia Hospital Sleep Disorders Program for their help in the conduct of this study. They also thank Drs. Penny Brasher and Michael Schulzer for their help with the statistical analysis.

Grant Support: By way of a Grant-in-Aid from ResMed Corp., Poway, California, and Vitalaire Canada Inc., Mississauga, Ontario, Canada; and a Michael Smith Foundation for Health Research Infrastructure Grant (Sleep-Disordered Breathing). One Remmers Sleep Recorder (formerly SnoreSat, Sagatech Electronics Inc., Calgary, Alberta, Canada) was provided on loan for the duration of the study. Dr. Mulgrew is supported by a BC Lung Fellowship and by the CIHR/HSFC IMPACT training program. Dr. Ayas is supported by a Michael Smith Foundation for Health Research Scholar Award, a CIHR/BC Lung Association New Investigator Award, and a Departmental Scholar Award from the University of British Columbia.

Potential Financial Conflicts of Interest: Grants received: N.T. Ayas (Respironics Inc.), C.F. Ryan (ResMed Corp., Vitalaire Canada, Inc.).

Requests for Single Reprints: Frank Ryan, MB, The Lung Centre, 7th Floor, Diamond Health Care Centre, 2775 Laurel Street, Vancouver, British Columbia, V5Z 1M9, Canada; e-mail, fryan{at}interchange.ubc.ca.

Current Author Addresses: Drs. Mulgrew, Fox, Ayas, and Ryan: The Lung Centre, 7th Floor, Diamond Health Care Centre, 2775 Laurel Street, Vancouver, British Columbia V5Z 1M9, Canada.

Author Contributions: Conception and design: C.F. Ryan.

Analysis and interpretation of the data: A.T. Mulgrew, C.F. Ryan.

Drafting of the article: A.T. Mulgrew, C.F. Ryan.

Critical revision of the article for important intellectual content: A.T. Mulgrew, N.T. Ayas.

Final approval of the article: A.T. Mulgrew, N. Fox, N.T. Ayas, C.F. Ryan.

Provision of study materials or patients: N.T. Ayas, C.F. Ryan.

Statistical expertise: A.T. Mulgrew, N.T. Ayas.

Obtaining of funding: C.F. Ryan.

Administrative, technical, or logistic support: A.T. Mulgrew, N. Fox.

Collection and assembly of data: N. Fox.

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