Between 10% and 17% of Americans have moderate to severe sleep apnea, according to recent estimates. The prevalence of the condition has been increasing in recent years, due in part to the escalating obesity rate in the United States. However, an estimated 80% of those with sleep apnea remain undiagnosed.
Addressing the Issue
“Polysomnographs are considered the reference standard for an obstructive sleep apnea (OSA) diagnosis, but it requires specialized facilities,” explains Dr. Qaseem, lead author of the recent guidelines on OSA from the American College of Physicians (ACP). “Polysomnographs are also resource intensive and expensive and require patients to stay overnight for observation. As an alternative to polysomnographs, portable monitors are increasingly being used because they are much cheaper and more convenient for patients.” Portable monitors are broken down into types II through IV, with polysomnographs being designated as type I (Table 1).
The ACP recommends that a sleep study be performed for patients with unexplained daytime sleepiness. “This is a weak recommendation based on low-quality evidence,” Dr. Qaseem says, “but we believe that there is a need to have a targeted approach to diagnosing OSA. This starts with evaluation of the risk factors and common symptoms. Patients with daytime sleepiness have been shown to be the most responsive to OSA treatment, whereas there is a lack of evidence supporting treatment benefits to improve other outcomes, such as hypertension, diabetes, or coronary disease, especially in patients without daytime sleepiness.”
To perform a sleep study in these patients, the ACP recommends polysomnographs for diagnostic testing. “If polysomnographs are available, they should be used,” adds Dr. Qaseem. “Portable sleep monitors are recommended in patients without serious comorbidities as an alternative if polysomnographs are not available. Polysomnographs, however, are considered the gold standard.” One of the issues with the portable monitors, according to Dr. Qaseem, is that they tend to have high positive likelihood ratios in general but low negative likelihood ratios for various Apnea Hypopnea Index cutoff points. Monitors with more channels perform better than those with fewer channels. Providers should ensure that patients who are unable or unwilling to undergo polysomnographs understand that portable monitors have reliability issues and that results obtained from using them should be considered carefully.
Among the portable monitors, determining the best option for diagnosing OSA is difficult because of a lack of comparative effectiveness studies. Still, portable monitors are preferable over the multiple questionnaires that are available for diagnosing OSA (Table 2). “Evidence was insufficient to determine the diagnostic accuracy of most questionnaires, whereas the evidence behind portable monitors is of moderate quality,” Dr. Qaseem says. “Questionnaires may be helpful in predicting risk for OSA, but the sensitivity and specificity had a wide range.”
A Need for More Research
Dr. Qaseem believes additional research is needed. “Preoperative screening for OSA is an important topic that has gained the interest of many healthcare providers and researchers,” he says. “However, whether it improves patient outcomes has yet to be determined. We also need to conduct more research that explores the utility of an OSA diagnosis in patients with comorbid conditions like congestive heart failure or neurologic disorders.” Dr. Qaseem adds that interest is growing in the use of phased testing—which involves a series of tests that may be done depending on the results of initial tests—in comparison with full, overnight polysomnograph testing; data are currently lacking in this area.
Evidence shows that patients with OSA have higher rates of healthcare use, more frequent and longer hospital stays, and greater healthcare costs before their diagnosis than after it. “Providers who have patients with tiredness, fatigue, and unrefreshing sleep should look for unexplained sleepiness and perform a sleep study in those who have yet to determine if they have OSA,” concludes Dr. Qaseem. “Providers can refer to the ACP guidelines to help diagnose OSA in their patients.”