Barbara Phillips, MD, MPH, FCCP: The Problem with Sleep Apnea Diagnoses

OCTOBER 17, 2018
Kevin Kunzmann
At least 1 in 10 US residents are inflicted with sleep apnea—or at least, the broad definition of sleep apnea.

In an interview with MD Magazine® while attending the 2018 CHEST Annual Meeting in San Antonio, TX, Barbara Phillips, MD, MPH, FCCP, of the University of Kentucky College of Medicine, sat down to discuss the prevalence of the condition in the US. Unfortunately, the patient population is large, diverse, and differing in symptoms and clinical characteristics. As a former president of CHEST, Phillips expressed disappointment with the minimal clinical development towards answering a critical question: what is sleep apnea?



MD Mag: How prevalent is sleep apnea in the US?

Phillips: A conservative estimate would be about 10%. The problem with answering that question is—wait for it: we still don't know what sleep apnea is. One of the most interesting sessions that I went to at CHEST was about the phenotypes of obstructive sleep apnea, and what that means is there are all different kinds of people who are diagnosed with sleep apnea.

There's little kids with big tonsils; they're skinny old ladies that have droopy soft palates, so the back of their throat closes off; there's a stereotypic big, heavy middle-aged man; there's the Chinese individual who has a short mandible or short lower jaw. And all of those people could be diagnosed with sleep apnea in a sleep laboratory. But it's becoming increasingly clear that not all of those people are at the same risk for bad things to happen.

I have to say that I'm a little discouraged after this meeting, because we still don't know what sleep apnea is, and we still don't know who will benefit from treatment. We have yet to demonstrate in a randomized controlled trial that treating sleep apnea with CPAP reduces death rates, car crashes, cardiovascular risk, or anything else. And I think the reason for that is because we are not identifying sleep apnea correctly, and we don't know how. And that's what this talk was all about.

It's increasingly clear that the apnea plus hypopnea index—which is the number of times you stop breathing (an apnea) or struggle to breathe (a hypopnea) per hour of sleep—is a simplistic, overused, not very replicable measure that doesn't predict much of anything. So when you try to identify people, ‘Well, we'll just say that everybody with an apnea plus hypopnea index of over 15 has sleep apnea,’ in that group, you're getting people who don't have sleep apnea.

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