Home Sleep Testing as Good as Laboratory Testing for Apnea

Nicola M. Parry, DVM

January 23, 2017

Data from home sleep testing are as good as those from laboratory-based testing for the diagnosis and management of obstructive sleep apnea (OSA), a new study shows.

Ching Li Chai-Coetzer, MBBS, PhD, from Repatriation General Hospital, Adelaide, South Australia, and colleagues published the results of their multicenter, randomized, noninferiority study online January 24 in the Annals of Internal Medicine.

"Outcomes for patients managed with manually scored, multichannel respiratory information ([level 3; L3] study) were not clinically inferior to outcomes in those managed with full PSG [polysomnography] data, which supports the use of L3 studies in clinical practice," the authors write.

The rising prevalence of OSA has increased demand for diagnostic sleep services. Whereas laboratory-based PSG is the gold standard tool for assessing OSA, it is labor-intensive, time-consuming, and expensive. As a consequence, interest in the use of home-based sleep studies to diagnose OSA has grown. According to the authors, in-home devices "record full PSG data (level 2 [L2] studies) or have fewer recording channels (level 3 [L3] and level 4 [L4] studies) without electroencephalography, electrooculography, or electromyography to score sleep stages."

Although studies have shown that limited-channel testing can be as effective as PSG for assessing OSA and guiding its management, it has not been clear whether these findings apply to real-world settings and across a broad range of patients.

The researchers therefore conducted the trial in 406 sleep clinic patients with suspected OSA. They aimed to compare patient outcomes and physician decision making among patients who received limited-channel testing with those who received full PSG.

The researchers performed the study at seven academic sleep centers across Australia. Patients underwent full laboratory-based PSG for 1 night and were then randomly assigned to one of three groups for assessment based on full PSG (L1), cardiorespiratory data only (to simulate home sleep testing; L3), or oximetry and heart rate data only (to simulate overnight oximetry testing; L4).

The study's primary outcome was change in Functional Outcomes of Sleep Questionnaire (FOSQ) score at 4 months from baseline. Secondary outcome measures included changes in the Epworth Sleepiness Scale (ESS) score, the Sleep Apnea Symptoms Questionnaire, continuous positive airway pressure compliance, and physician decision making. The researchers used an intention-to-treat analysis including all patients to better reflect the real-world effect of replacing PSG with home-based testing.

Dr Chai-Coetzer and colleagues found that the FOSQ score improved significantly in all groups (P < .001) from baseline to 4 months. However, they also found that the change in FOSQ score was not inferior for patients in the L3 (mean difference [MD], 0.01 [95% confidence interval (CI), −0.46 to 0.49; P = .96]) or L4 (MD, −0.46 [CI, −0.94 to 0.02; P = .058]) groups when compared with the change for the L1 group (noninferiority margin [NIM], −1.0).

ESS score also improved significantly in all groups (P < .001) from baseline to 4 months. When compared with the L1 group, the change in ESS score was not inferior for the L3 group (MD, 0.08; CI, −0.98 to 1.13; P = .89), but was inconclusive for the L4 group (MD, 1.30; CI, 0.26 to 2.35; P = .015; NIM, 2.0).

The researchers also found a smaller improvement in Sleep Apnea Symptoms Questionnaire score when comparing the L4 and L1 groups (−17.8 vs −24.7; P = .018), as well as less continuous positive airway pressure use (4.5 vs 5.3 hours per night; P = .04) and lower physician diagnostic confidence (P = .003). However, they found no statistically significant difference in these measures between the L3 and L1 groups.

Although these results reassure clinicians about the clinical use of L3 study data in the management of patients with suspected OSA, the authors stress that clinicians should take extra care when using L4 data because the data showed that some secondary outcomes were worse in the L4 group.

"Further studies are needed to compare clinical outcomes and cost-effectiveness for the 3 levels of sleep study testing when conducted in the unattended home environment and perhaps after specific training in the use of L4 studies," they conclude.

In an accompanying editorial, Lucas M. Donovan, MD, from the University of Washington, Seattle, and Sanjay R. Patel, MD, from the University of Pittsburgh, Pennsylvania, welcome the study's findings.

"These results support the contention that a home-based diagnostic and treatment strategy leads to outcomes that are as good as" a laboratory-based strategy, they write.

With respect to the finding that OSA treatment decisions based on oximetry alone resulted in worse outcomes, the editorialists link this to lower physician diagnostic confidence. "This may reflect a lack of training in the use of oximetry, given that no professional society has developed standards for the scoring or reporting of overnight oximetry testing."

The editorialists also acknowledged some weaknesses of the study, including the lack of assessment of treatment-associated cardiovascular effects and exclusion of patients with active cardiovascular disease. They stress that because OSA and cardiovascular disease often coexist, future studies should include these patients. Also, because all testing was performed in a sleep laboratory, signal quality was probably better than it would have been with home-based testing.

Nevertheless, they emphasize that the results of this study have shown the value of using home-based testing in a broad range of patients with suspected OSA.

"This is welcome news to providers and other stakeholders interested in delivering cost-effective care," they conclude. Clinicians' use of home-based testing can help to reduce patients' wait times for testing, and can expand access to underserved populations, such as patients in rural areas or those who lack transportation or overnight childcare.

This study was funded by the National Health and Medical Research Council of Australia and the Repat Foundation. Several coauthors and Dr Patel have reported various financial and nonfinancial relationships with various companies and organizations: Air Liquide Healthcare; American Sleep Foundation; AstraZeneca; Biotech Pharmaceuticals; Fisher & Paykel; GlaxoSmithKline; Medtronic, Inc; Philips Respironics; and ResMed. The remaining authors and editorialist have disclosed no relevant financial relationships.

Ann Intern Med. Published online January 24, 2017. Article abstract, Editorial extract

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