Home Benefits and Drawbacks
Validated, established home tests play an important diagnostic role and offer other benefits, according to Edward M. Weaver, MD, MPH, professor of otolaryngology-head and neck surgery and chief of sleep surgery at the University of Washington School of Medicine in Seattle. “Patients sleep in their own bed. They’re less cumbersome to set up, so patients often sleep more naturally.”
Explore This IssueSeptember 2020
The main limitation of home sleep apnea tests is the lack of a direct sleep measure, or EEG, which impacts some sleep apnea parameters, or underestimates them, said Dr. Weaver. “For example, the apnea-hypopnea index is defined as the number of breathing pauses per hour of sleep, so the duration of sleep is part of the definition. Home sleep apnea tests use proxies for measurement of sleep, such as the recording time or actigraphy [measure of activity]. Some proxies are better than others. In-lab polysomnography directly measures sleep by EEG, so it has an accurate measure of sleep time, providing greater accuracy. In-lab testing is also more reliable because it’s monitored, so if something goes haywire during the test, it gets fixed quickly, whereas a home test may just show a technical failure,” he said.
Most home sleep apnea tests still require direct visual review of the raw data that are collected. There’s some physician review, but the amount of review may vary, because the scoring of these home sleep apnea tests can be automated. —Eric J. Kezirian, MD, MPH
Home sleep tests have obvious benefits for appropriate patients, agreed Eric J. Kezirian, MD, MPH, professor of sleep medicine and vice chair of the Caruso Department of Otolaryngology-Head and Neck Surgery at the University of Southern California in Los Angeles. “The general advantages include lower costs, greater convenience, and the possibility of a more natural assessment because there are fewer monitors attached to the body, and the patient is sleeping in their own bed,” he said. “The disadvantages include the fact that there can be displacement of monitoring devices, making the study of inadequate quality and needing to be repeated, and the fact that fewer monitors collect less information.”
The AASM guideline acknowledges that “measurement error is inevitable” in the technology because EEG, electro-oculogram (EOG), and electromyogram (EMG) typically aren’t monitored. It also states that because of cost and lack of proximity to a sleep clinic, home testing may be “less costly and more efficient” for appropriate patients.
Home sleep testing measures limited parameters by comparison: usually oxygen saturation, pulse, respiratory flow, and respiratory effort. Because in-lab polysomnography provides a fuller set of measures for sleep apnea and other sleep issues, such as sleep-stage abnormalities, said Dr. Weaver, patients with complicated sleep apnea should spend the night in a clinic to confirm diagnosis—as should anyone with suspected sleep apnea who receives a negative result from a home test.
Why do some patients with highly suspected OSA get a negative result on their home test? Technical failure, such as unreadable or missing data or incorrectly attached monitors, can happen at home, said Dr. Weaver. Other potential pitfalls of home tests include a mismatch between actual sleep time and proxy sleep time, which may happen if a patient has difficulty falling asleep or cannot stay asleep during the night, and other sleep issues that throw off the results, such as a limb movement disorder.
If a patient’s home test is negative, but they still have suspected sleep apnea due to their symptoms, most insurance policies will cover a follow-up in-lab test. “I don’t think home sleep apnea testing is causing people to be misdiagnosed,” said Dr. Weaver. “It may in fact be increasing access to testing, so more people are getting diagnosed.”
“An at-home sleep study can only tell if a patient has obstructive or central sleep apnea; it’s most effective to diagnose moderate to severe apnea. Mild OSA can result in a false negative result, but typically a sleep lab would be able to pick it up,” said Dr. Takashima. “There are many other sleep disorders that wouldn’t be picked up by a home sleep study, such as narcolepsy or sleepwalking.”
Home sleep tests may underestimate OSA severity and miss other sleep disorders because they cannot detect events that cause patients to awaken without drops in oxygen levels and cannot always detect if a patient is awake for prolonged periods during the night, noted Dr. Kezirian. “Most home sleep apnea tests still require direct visual review of the raw data that are collected. There’s some physician review, but the amount of review may vary, because the scoring of these home sleep apnea tests can be automated,” he said.