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Home Diagnosis of Sleep Apnea

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Sleep specialists can sometimes diagnose and manage obstructive sleep apnea (OSA) with home-based tests instead of in-lab polysomnography, new research suggests.

In a randomized trial prepublished online in Chest on February 19, Canadian investigators showed that both approaches led to similar four-week outcomes in daytime sleepiness, sleep quality, blood pressure, and adherence to treatment.

Guidelines recommend overnight polysomnography for OSA diagnosis, but the authors note that testing at a patient’s home may be more accessible and cost-effective.

“In our region (and many others in North America), the wait times for OSA testing are quite long,” lead author Dr. Robert P. Skomro told Reuters Health by email. “We recognized that with rapid developments in the technology we could use home monitors to test breathing, oxygen levels and other parameters, thereby shortening the wait times for testing.”

Dr. Skomro, from the University of Saskatchewan in Saskatoon, and his colleagues randomized 102 adults to home monitoring or in-lab testing. For home testing, patients used an Embletta device (Medcare Co.), which recorded nasal airflow, thoracic and abdominal respiratory effort, oxygen saturation, heart rate and body position. In the lab, technicians monitored the same parameters using the Sandman PSG diagnostic system, and patients also had electroencephalography, electro-oculography, chin and anterior tibialis electromyography, and electrocardiograph.

Subjects in the home testing group also spent one night in the lab for polysomnography, and the in-lab group had one night of home monitoring, so the two procedures could be compared.

Overall, 89 patients had OSA, including 44 in the home-tested group and 45 in the laboratory group. The OSA threshold in the lab group was an apnea/hypopnea index above 5. For diagnosis in the home-tested group, the researchers used a score above 5 on the respiratory disturbance index, which they calculated as the sum of recorded apneas and hypopneas divided by the recording time.

For lab-diagnosed patients, a technician titrated continuous positive airway pressures (CPAP) for therapy. Patients in the home-testing group received auto-CPAP therapy for one week followed by three weeks of fixed-pressure CPAP based on the 95% of auto-CPAP pressure.

Ten patients rejected CPAP therapy outright, and another 9 were lost to follow-up, leaving 33 home test patients and 37 polysomnography patients for analysis at four weeks.

Dr. Skomro and his colleagues report that both groups had improvements on the Epworth Sleepiness scale, the Pittsburgh Sleep Quality Index, and SF-36 scores, and in systolic and diastolic blood pressures, with no significant differences between groups. CPAP compliance was also similar (5.6 hr/night in the lab group vs 5.4 hr/night in the at-home group).

Seventy-six percent of subjects preferred home monitoring testing to polysomnography. However, 17% of patients had to repeat the home monitoring because of technical factors, which could affect cost efficacy. The researchers estimate the costs of a home-based program to range from CAN$400-$450 (roughly, USD$388-$437), plus physicians’ fees and costs incurred by patients. (Guidelines from the American Academy of Sleep Medicine for use of portable devices to diagnose OSA — published in 2007 – note that cost savings of 22-33% have been reported for home testing compared to in-lab polysomnography.)

The investigators say their findings may not be generalizable since their study was performed at a single tertiary sleep center in a population without serious medical comorbidities but with a high likelihood of OSA.

They recommend that home management be restricted “to a subset with high clinical suspicion of OSA and no contraindication to either level III testing or AutoCPAP.” Indeed, the American Academy of Sleep Medicine guidelines state that home diagnosis should be used only “in patients with a high pretest probability of moderate to severe OSA” and not when patients have “significant comorbid medical conditions,” unless “in-laboratory polysomnography is not possible by virtue of immobility, safety, or critical illness.”

“No test is perfect and has to be interpreted in appropriate context and clinical scenario,” Dr. Skomro said. “Previous work has demonstrated that home-based testing is not accurate enough in subjects who are not likely to have moderate to severe OSA.”

He said that there are many reasons not to use level III testing, including patients’ ability to apply the monitor and physicians’ lack of expertise in using the device and interpreting the data.

“There are contraindications to AutoCPAP as well,” he continued, “such as presence of heart failure, lung disease, neurological disease, and previous upper airway surgery.”

“These technologies should be used by qualified staff and interpreted by qualified sleep medicine physicians,” he said.

Chest 2010.