Sleep Apnea at the American Thoracic Society Annual Meeting
In recent years, there has been a greater recognition of the cardiovascular and other health-related effects of breathing-related sleep disorders, particularly obstructive sleep apnea (OSA). At the same time, the disorder is being recognized and diagnosed more often. Today, about one in five adults has a high risk of OSA. The diagnosed prevalence is 2% to 20% depending on how the condition is defined.12,13
Thus, it is not surprising that more than 100 abstracts to be presented at ATS will deal with sleep-disordered breathing. A major focus is the link between metabolic disorders and OSA. One study, for instance, found that more than 25% of 255 OSA patients studied had impaired glucose tolerance, a major risk factor for diabetes and other metabolic disorders.14 Others found that the severity of OSA predicted diabetes risk, impaired pancreatic beta cell function, and insulin resistance, and was also associated with a significantly higher incidence of arterial hypertension.15, 16, 14 Take-home message: Patients who have been diagnosed with OSA, or who are at risk for OSA, most likely have other cardiometabolic symptoms that should be addressed.
Conversely, clinicians may want to evaluate patients with cardiometabolic and OSA risk factors for OSA. That is particularly important given evidence that treating OSA can improve metabolic markers. In one meta-analysis being presented at ATS, researchers evaluated 9 studies with a total of 220 subjects and found a favorable effect of continuous positive airway pressure (CPAP) on insulin resistance, although they noted that the studies were mostly observational.17
However, a double-blind randomized, crossover clinical trial published in The New England Journal of Medicine ahead of the meeting, which will also be presented orally at ATS, found that CPAP treatment for 3 months significantly reduced blood systolic and diastolic blood pressure, total cholesterol, non HDL cholesterol, LDL cholesterol, triglycerides, and glycated hemoglobin, compared to sham treatment. It reversed the metabolic syndrome in 11 of the 86 treated patients (13%) compared to only 1 who had the sham treatment.18
Just because your patients are diagnosed with OSA doesn’t mean you have to turn them over to a sleep specialist for treatment. A study that will be presented at ATS found that after 6 months of management in a primary care setting, patients with symptomatic, moderate-to-severe OSA managed in a primary care setting had comparable outcomes (change in Epworth Sleepiness Scale, Functional Outcomes of Sleep questionnaire, and CPAP compliance) to a similar group receiving usual care in a sleep center.19 The primary care intervention that involved home-based auto-titrating of CPAP.
Clinicians should also be aware of “overlap syndrome,” in which patients have comorbid OSA and COPD. An analysis of 4,116 individuals with COPD ranging from mild to very severe found that 15% also had physician-diagnosed OSA. These patients were more likely to be males who had a history of heavy smoking. They were also more likely to have cardiovascular disease (CVD), diabetes, and hypertension, with a much higher risk of heart failure. The more severe their COPD, the more likely they were to have OSA.20 Take-home message: To reduce the risk of comorbid heart failure, identify OSA in COPD patients and COPD in OSA patients and treating both conditions simultaneously.