The American College of Physicians (ACP) issued a clinical practice guideline in August (see doi:10.7326/M12-3187), which basically supports performing a sleep study for patients with unexplained daytime sleepiness. There are many adverse outcomes associated with sleep apnea (OSA), including cardiovascular disease (with the degree of risk associated with the degree of disordered breathing), hypertension, cognitive decline, metabolic abnormalities including type 2 diabetes, increased peri-operative mortality, all-cause mortality (esp. with higher levels of disordered breathing) etc. However, some clinicians have been ordering sleep studies in anticipation of improving these associated conditions, which is problematic both because of the remarkable baseline frequency of OSA in the population (on the order of 10-17%) which increases with age, and the data are lacking that finding OSA and treating it leads to any improvement in these associated conditions (e.g. CPAP does not reduce mortality or coronary heart disease in those without daytime sleepiness; there was small reduction in blood pressure in those with daytime sleepiness and using CPAP, but unclear if true in those who are asymptomatic).
The ACP’s specific recommendations:
— ACP recommends a sleep study for patients with unexplained daytime sleepiness (weak recommendation low-quality evidence)
— ACP recommends formal polysomnography in a sleep lab for diagnostic testing in patients suspected of OSA. they recommend portable sleep monitors in patients without serious comorbidities (e.g. chronic pulmonary disease, heart failure, neurologic disorders, where portable monitors have not been evaluated) as an alternative to polysomnography, when polysomnography is not available for diagnostic testing (weak recommendation, moderate-quality evidence). Studies are limited with direct comparisons between the different types of portable monitors, though it makes sense not to use ones that cannot differentiate between central and obstructive sleep apnea, since CPAP may be contraindicated if central. [Although ACP recommends home monitors “when polysomnography not available”, many insurers are requiring the home based monitors unless there are significant comorbidities.]
A couple of comments. First, I really agree with their conclusions. Lacking clear data on clinical benefit, we should be focusing the use of sleep studies on those with functional impairment which might be related to OSA and where CPAP does improve outcomes: i.e., those with daytime somnolence. In this regard it is important to keep in mind that, on the one hand, only 37% of patients with severe OSA had daytime somnolence, and on the other, mortality associated with severe sleep apnea is unrelated to daytime somnolence (but, again, intervention studies are lacking, with no difference in cardiovascular mortality, as noted above). Second, and most importantly, we should continue to focus our attention on the prevention and treatment of obesity, the best-documented risk factor for OSA (though, 15% of OSA diagnoses are in non-obese people –another study confirmed that 32% of men with documented OSA were non-obese with 11% having normal weight, and 12% of women were non-obese with 3% being of normal weight).
Geoff