Chest
Volume 129, Issue 1, January 2006, Pages 67-75
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Original Research: Sleep Medicine
A Continuous Positive Airway Pressure Trial as a Novel Approach to the Diagnosis of the Obstructive Sleep Apnea Syndrome

https://doi.org/10.1378/chest.129.1.67Get rights and content

Objectives

Treatment of obstructive sleep apnea syndrome (OSA) is often delayed because polysomnography, the recommended standard diagnostic test, is not readily available. We evaluated whether the diagnosis of sleep apnea could be inferred from the response to a treatment trial with nasal continuous positive airway pressure (CPAP).

Design

Study on diagnostic accuracy.

Setting

Sleep-disorders clinic of a university hospital.

Patients

Seventy-six sleepy snorers consecutively referred for sleep apnea evaluation.

Interventions

CPAP treatment trial over 2 weeks as an initial diagnostic test in comparison with polysomnography, and treatment success over ≥ 4 months.

Measurements and results

The main outcome was diagnostic accuracy of the CPAP trial. The trial result was positive if the patient had used CPAP for > 2 h per night and wished to continue therapy. This suggested sleep apnea. The trial was evaluated in terms of predicting an obstructive apnea/hypopnea index (AHI) > 10/h during polysomnography performed for validation, and in terms of identifying sleep apnea patients treated successfully over ≥ 4 months. Forty-four of 76 patients (58%) had sleep apnea as confirmed by an AHI > 10/h. The CPAP trial predicted sleep apnea with a sensitivity of 80%, a specificity of 97%, and positive and negative predictive values of 97% and 78%, respectively. In 35 of 76 sleep apnea patients (46%) with positive CPAP trial results, polysomnography could have been avoided. These patients were prescribed long-term CPAP therapy. After 4 months, 33 of 35 patients (94%) still used CPAP, and their symptoms remained improved. These patients were identified by the CPAP trial with positive and negative predictive values of 92% and 100%, respectively.

Conclusions

In a selected population, a CPAP trial may help to diagnose OSA, to identify patients who benefit from CPAP, and to reduce the need for polysomnography.

Section snippets

Patients

Successive patients referred by primary care physicians to the sleep-disorder center for evaluation of suspected OSA were enrolled if they were habitual snorers, complained of daytime sleepiness, had an Epworth sleepiness scale (ESS) score ≥ 8,1213 and gave informed consent to the study protocol, which was approved by the hospital ethics committee. Exclusion criteria were as follows: a contraindication for CPAP or auto-adjusting CPAP (ie, unstable congestive heart failure, significant lung

Baseline Patient Characteristics

Of 195 successive patients referred for evaluation of sleep apnea, 76 patients (39%, 15 women and 61 men) fulfilled inclusion criteria and participated in the study. Seven patients (4%) refused participation, 10 patients (5%) had to be excluded because of inability to understand German, and 102 patients (52%) had one or several medical exclusion criteria (known sleep disorder or previous CPAP therapy, medical, neurologic or psychiatric disorder explaining some of the symptoms).

The 76 patients

Discussion

We evaluated a novel approach to the diagnosis of patients with clinically suspected OSA. This approach is based on observing the response to a CPAP treatment trial over 2 weeks as the initial diagnostic step rather than on polysomnography, the standard test. The outcome of the CPAP trial was assessed in a simple way by the response to two questions reflecting the benefit perceived by the patients, their propensity to continue treatment, and the objectively measured compliance with CPAP during

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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

    Unconditional grant support was provided by the Lung Leagues of Zurich and Schaffhausen, Switzerland.

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