The USPSTF and screening for obstructive sleep apnea: Dispelling misconceptions

CRITERIA FOR A GOOD SCREENING TEST

Principles for screening outlined by Wilson and Jungner¹⁰ were:

• The condition we are trying to detect should be important
• There should be an accepted treatment for it
• Facilities for diagnosis and treatment should be available
• Testing should be acceptable to the population
• There should be cost benefit to the expense of case-finding
• There should be an agreed-upon policy on whom to treat as patients.

Screening for obstructive sleep apnea meets many of these criteria.

Obstructive sleep apnea is important

Solid evidence exists that obstructive sleep apnea exerts a bad effect on health and quality of life. Population-based studies that enrolled participants irrespective of symptoms indicate that the risk of death is about twice as high in those with severe obstructive sleep apnea as in those without, and treatment exerts benefit especially in those with cardiovascular risk.^13,14 Therefore, the criterion for screening that says the disease must be important is met.

Pathophysiologic pathways by which obstructive sleep apnea causes harm include intermittent hypoxia, hypercapnia, intrathoracic pressure swings, and autonomic nervous system fluctuations. 

Treatment is beneficial

The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recognized obstructive sleep apnea as a cause of hypertension.¹⁵

Treating obstructive sleep apnea lowers blood pressure, which in turn improves cardio­vascular outcomes. Effects are most pronounced in those with resistant hypertension. The reduction in blood pressure is only about 2 to 3 mm Hg, but this translates to a 4% to 8% reduction in future risk of stroke and coronary heart disease.^16,17

The Continuous Positive Airway Pressure Treatment of Obstructive Sleep Apnea to Prevent Cardiovascular Disease multicenter randomized clinical trial investigated the impact of treating obstructive sleep apnea with continuous positive airway pressure (CPAP) compared with usual care.¹⁸ Although no statistically significant difference was seen in the composite cardiovascular outcome, propensity-score analysis in the subgroup adherent to CPAP demonstrated a lower composite of cerebral events in those who used CPAP for at least 4 hours a day.

The findings from this trial are difficult to interpret for several reasons. Adherence to CPAP was suboptimal, the severity of obstructive sleep apnea might not have been bad enough to permit observation of a significant treatment effect, and the generalizability of the findings is unclear, given that many of the participants were from underresourced regions.¹⁹

In a meta-analysis of cohort studies comprising more than 3 million participants, Fu et al found that the cardiovascular mortality rate was 63% lower in those with obstructive sleep apnea using CPAP than in untreated patients.²⁰

APPLY CLINICAL JUDGMENT

Overall, the USPSTF report is intended to guide healthcare decision-makers. However, it includes a caveat to not substitute the findings for clinical judgment and to interpret the findings in the context of collateral pertinent information.²

Although no high-quality data exist to support or refute global screening for obstructive sleep apnea in the primary care setting, the high prevalence of this disease and its detrimental effects on health and quality of life if left untreated should not be dismissed.

Arguably, most patients who present to primary care clinics are not healthy, are not free of symptoms, and are at risk of obstructive sleep apnea because they are obese. Testing for it is therefore more like case-finding than screening.

In view of the serious consequences of obstructive sleep apnea, we should view the situation as an opportunity to examine the impact of screening. Perhaps using electronic medical records, we could collect sleep-specific measures, implement case-finding strategies, and perform pragmatic clinical trials to inform and guide optimal and cost-effective screening approaches.

Patients with common disorders such as obstructive sleep apnea are often considered asymptomatic until asked about symptoms. Therefore, careful review of systems incorporating sleep health is important, particularly as patients do not typically volunteer this information. Obtaining this history does not necessarily fall under the USPSTF’s recommendation not to screen.

Future efforts should focus on leveraging the electronic medical record platform to collect sleep-specific measures, implementing case-finding strategies, and performing pragmatic clinical trials in the primary care setting to inform and guide optimal and cost-effective approaches to screening.