Evidence Lacking on Screening for Sleep Apnea: USPSTF

By Will Boggs MD

June 17, 2016

NEW YORK (Reuters Health) - Current evidence is insufficient to determine the balance of benefits and harms of screening asymptomatic adults for obstructive sleep apnea (OSA), according to a draft recommendation statement from the U.S. Preventive Services Task Force (USPSTF).

The panel focused solely on primary care patients with no symptoms or unrecognized symptoms, noted Dr. Alex Krist, Task Force member from Virginia Commonwealth University, Richmond, in email to Reuters Health. "There may be reasons to consider testing in other settings that are outside the scope of the Task Force, such as in an occupational health clinic caring for commercial truck drivers or airline pilots."

An estimated 10% of Americans have mild OSA, and 3.8% to 6.5% have moderate to severe OSA, but whether asymptomatic individuals should be screened for OSA remains unclear.

Dr. Krist and colleagues on USPSTF investigated whether the use of screening questionnaires in asymptomatic adults could accurately identify individuals who would benefit from further testing for OSA.

They found no studies that evaluated the effect of screening for OSA on health outcomes, although there was adequate evidence that continuous positive airway pressure (CPAP) and mandibular advancement devices (MAD) can improve apnea-hypopnea index (AHI) in individuals referred for treatment.

USPSTF also found inadequate evidence on the direct harms of screening for OSA.

"In theory, screening for OSA could improve mortality by identifying OSA early and providing treatment before it can adversely influence mortality," the report says. "However, despite the observed association between severe AHI and increased mortality, no studies have demonstrated an improvement in mortality with treatment of OSA."

The draft statement goes on to say, "The identification of valid and reliable clinical prediction tools that could accurately determine which asymptomatic persons (or persons with unrecognized symptoms) would benefit from further evaluation and testing for OSA is needed. In addition, studies that evaluate the effect of OSA treatments or interventions on health outcomes (e.g., all-cause and cardiovascular mortality, cardiovascular disease and cerebrovascular events, motor vehicle accidents, and cognitive impairment) that are adequately powered and have an appropriate length of follow-up are needed. Studies are also needed that evaluate whether improvement in AHI (for mild, moderate, and severe OSA) leads to improvement in health outcomes. These represent critical gaps in the current evidence base."

Other organizations recommend OSA screening in various situations. The American College of Physicians weakly recommends conducting a sleep study for patients with unexplained daytime sleepiness, and the American Academy of Sleep Medicine recommends that routine health maintenance evaluations include questions about OSA and evaluation for risk factors (obesity, retrognathia, and hypertension), followed by a comprehensive sleep evaluation for individuals with positive findings.

The National Institute for Health and Care Excellence says moderate to severe obstructive sleep apnea/hypopnea syndrome can be diagnosed from patient history and a sleep study using oximetry or other monitoring devices conducted in the patient's home.

"While there is insufficient evidence to recommend for or against OSA screening in patients without known symptoms, clinicians should use their best judgment when determining whether or not to evaluate an individual patient for OSA," Dr. Krist said. "Not only is more research needed to better understand the effect of treating OSA on important health outcomes, but we need research to determine which groups of patients with unrecognized symptoms might or might not benefit from screening."

Dr. Walter McNicholas, director of University College Dublin's pulmonary and sleep disorders unit, Dublin, Ireland, told Reuters Health by email, "OSA is so highly prevalent that every practicing physician will regularly encounter patients with OSA. Thus, physicians should be alert for the possibility and include relevant symptoms such as snoring, witnessed apnea, and daytime fatigue/sleepiness in routine clinical assessment."

"A very interesting finding in the report is the very low proportion of patients who volunteer sleep-related symptoms to their primary care physician and the uncertainty among these primary care physicians regarding appropriate investigation and management," he said. "This aspect identifies a substantial knowledge deficit requiring improved education in primary care."

"The clinical significance of mild OSA is uncertain," Dr. McNicholas said. "Whereas severe OSA is relatively easy to diagnose and treat (usually with CPAP), those with milder disease are paradoxically more difficult to confidently diagnose, and management decisions can be more complex."

Dr. Michael Le Grande from Deakin University's Australian Center for Heart Health, North Melbourne, Victoria, told Reuters Health by email, "I generally agree with most of the conclusions regarding screening for OSA in the general population in asymptomatic adults. However, there are strong cases for screening in secondary prevention settings."

"There are now strong cases for routine screening in preoperative and surgical patients but more research is required in primary setting," he said. "The research in this area is rapidly developing (there are over 1,000 abstracts presented at the current Sleep 2016 Conference, for example: http://bit.ly/24OAf4h) and physicians should keep an open mind about future research in this area, which may demonstrate a case for screening in certain populations."

The USPSTF draft recommendation statement and draft evidence review have been posted for public comment through July 11, 2016.

SOURCE: http://bit.ly/1Pri7q0

USPSTF 2016.