The reported prevalence of obstructive sleep apnea (OSA) varies due to differing definitions of the condition, sampling bias and the year of study publication. A 2013 systematic review reported an estimated prevalence of 2 percent to 14 percent based on four community-level studies, while two studies conducted in the United States in the 1990s reported an estimated prevalence of 10 percent for mild OSA and 3.8 percent to 6.5 percent for moderate or severe OSA.
On June 14, the U.S Preventive Services Task Force (USPSTF) posted a draft recommendation statement(www.uspreventiveservicestaskforce.org) on screening for OSA in asymptomatic adults in primary care settings.
Following its first-ever draft evidence review(www.uspreventiveservicestaskforce.org) on the topic, the task force concluded there isn't enough evidence to assess the balance of benefits and harms of screening for OSA in adults without recognized symptoms of the condition -- an "I" statement.(www.uspreventiveservicestaskforce.org)
"The Task Force is calling for more research on whether screening in adults without known symptoms leads to improvements in health outcomes such as heart attacks, strokes, quality of life and mortality," said USPSTF member Alex Krist, M.D., M.P.H, in a news release.(www.uspreventiveservicestaskforce.org)
This draft recommendation doesn't apply to adults who have symptoms of or concerns about OSA, or who have an acute condition that could trigger the onset of OSA, such as a stroke. It also doesn't apply to children, adolescents or pregnant women.
- The U.S Preventive Services Task Force posted its first-ever draft recommendation statement June 14 on screening for obstructive sleep apnea (OSA) in asymptomatic adults in primary care settings.
- The task force concluded there isn't enough evidence to assess the balance of benefits and harms of screening for OSA in adults without recognized symptoms of the condition.
- This draft recommendation doesn't apply to adults who have symptoms of or concerns about OSA, or who have an acute condition that could trigger the onset of OSA, such as a stroke. It also doesn't apply to children, adolescents or pregnant women.
Symptoms of OSA include daytime sleepiness, fatigue, insomnia and problems from a lack of sleep such as issues with memory, concentration and mood changes. OSA also has been linked to cardiovascular disease and an increased risk of death.
Scope of Review
The USPSTF commissioned a systematic review to evaluate the evidence on the accuracy, benefits and potential harms of screening for OSA in asymptomatic adults seen in primary care, including those with unrecognized symptoms.
The systematic review also evaluated the evidence on the benefits and harms of treatment of OSA on intermediate outcomes (e.g., change in apnea-hypopnea index (AHI), sleepiness and blood pressure) and health outcomes (e.g., mortality, quality of life, cardiovascular and cerebrovascular events, and cognitive impairment). This review focused on studies in adults ages 18 and older.
Researchers found that OSA is more common in men than in women and that it increases with age through the sixth and seventh decade and then plateaus. Also, the prevalence difference between men and women narrows after menopause. In addition, observational studies found the prevalence of OSA progressively increases as body mass index increases in both men and women.
Using data from the Wisconsin Sleep Cohort Study, one study found a 10 percent increase in weight was associated with a six-fold increase in risk of incident OSA during four years of follow-up visits.
Accuracy of Screening Tests
The USPSTF examined two tools that are used to identify patients who are at higher risk of OSA: the Berlin Questionnaire and the Multivariable Apnea Prediction (MVAP) tool.
The Berlin Questionnaire was evaluated in a single cross-sectional study that sampled Norwegian residents from the National Population Register. Based on analyses that adjusted for oversampling of high-risk participants, the tool had a sensitivity of about 37 percent and a specificity of 84 percent when using an AHI cutpoint of 5 or greater. Using an AHI cutpoint of 15 or greater, the Berlin Questionnaire had a sensitivity of 43 percent and a specificity of about 80 percent. Overall, this study found poor accuracy for the Berlin Questionnaire.
Two studies evaluated the MVAP tool in primary care settings. And although both studies were published by the same research group from Philadelphia, one study was conducted in Medicare patients who had daytime sleepiness (n=452), while the other was conducted in patients with hypertension visiting internal medicine practices at a Department of Veterans Affairs medical center system and a university-based hypertension clinic (n=250).
With the Medicare patients in the first study who had daytime sleepiness, the MVAP had a sensitivity of 90 percent and a specificity of about 64 percent to predict severe obstructive sleep apnea syndrome (OSAS), which is defined as an AHI of at least 30 and an Epworth Sleepiness Scale score of more than 10. Among patients with hypertension, the MVAP had a sensitivity of about 92 percent and a specificity of about 44 percent to predict severe OSAS.
For the Medicare patients tested at home, portable monitor testing was added and the sensitivity and specificity of the MVAP to predict severe OSAS increased to about 91 percent and about 76 percent, respectively. For the patients with hypertension who were tested at home, the sensitivity decreased to about 88 percent and specificity increased to about 72 percent.
The two studies that evaluated the MVAP were both conducted in populations that had a high prevalence of OSAS (and thus were more likely to be symptomatic) and a high risk of spectrum bias.
The draft recommendation statement said that even though there were consistent findings establishing an association between severe OSA and increased mortality, the USPSTF didn't identify any studies that reported on change in AHI and an associated change in mortality. "Thus, it is unclear whether treatments that improve AHI would also improve mortality," the statement said.
Family Physician Expert's Take
Mandeep Ghuman, M.D., attending physician at the Dignity Health Family Medicine Residency Program at Northridge Hospital in Northridge, Calif., wrote about the clinical indicators of OSA in American Family Physician in 2011.
Although his research was focused on symptomatic patients with OSA, he told AAFP News that similar to the USPSTF team, he found it hard to compare studies as methodologies and definitions of OSA varied (i.e. different AHI cut-offs and using respiratory disturbance index as opposed to AHI).
"We still don't have great screening tools in primary care for symptomatic patients to make a diagnosis of OSA, so the benefit of screening asymptomatic patients is probably going to be minimal at best," Ghuman said.
When it comes to diagnosing symptomatic patients with OSA, he said the literature search for his study revealed that certain clinical characteristics increased the risk for patients having clinically significant OSA.
"The two most strongly associated were witnessed apnea from a sleep partner and moderate to severe snoring," Ghuman said. "In addition, other risk factors were advanced age, obesity, male gender and post-menopausal status. However, at the time, there were no clear cutoffs found for age or obesity that would prompt automatic consideration for the diagnosis."
For the treatment of diagnosed OSA, he said his patients who are able to tolerate continuous positive airway pressure (CPAP) have favorable results in alertness, reduced daytime fatigue and improved sleep patterns, with a more modest effect on their blood pressure control. "However, even with advances in CPAP masks, I still find a portion of my patients cannot tolerate using CPAP on a long-term basis," Ghuman said.
Ghuman pointed out that the most significant part of the USPSTF draft recommendation statement might have been the acknowledgement that at this time, there is a lack of clear evidence on the long-term health benefits of treating OSA, which he called disappointing.
"Since there is a lack of evidence on improvement in long-term health outcomes with treating OSA (both in symptomatic and asymptomatic patients) and no adequate screening tool for use in a primary care setting for asymptomatic patients, it would be difficult for me to institute the screening of asymptomatic patients within my primary care clinic setting," he said.
The USPSTF is providing an opportunity for public comment on this draft recommendation statement(www.uspreventiveservicestaskforce.org) and draft evidence review(www.uspreventiveservicestaskforce.org) until July 11.
The AAFP is reviewing the USPSTF's draft recommendation and will release its own recommendation after the task force publishes its final recommendation statement.
Related AAFP News Coverage
AHRQ Clinician, Patient Guides on Sleep Apnea Review Diagnosis, Management
Evidence Points to CPAP Devices as Most Effective Treatment
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American Family Physician: Sleep Disorders in Adults