The governing principle of obstructive sleep apnea (OSA) evaluation has long held that polysomnography (PSG) is the gold standard for measuring physiological events that define the disease. In this issue of the Journal of Clinical Sleep Medicine Lipatov and colleagues have cast some doubt on the true nature of that gold standard.1 The authors, following the dictum that patients whose test failed to prove pathology should be restudied, performed type III home sleep apnea testing (HSAT) in a group of patients who were symptomatic but had a normal apnea-hypopnea index by PSG. The current standards specify that repeat PSG is required, whether the original study was PSG or HSAT, in cases with negative initial testing. The authors found a high rate of positive respiratory event index (REI) in the subsequent home study. The findings suggest that the PSG had missed the diagnosis in a number of patients, labeling them as false negative by PSG. Perhaps it is not that surprising because the laws of physics should have warned us, according to Heisenberg's Indeterminacy Principle,2 that the act of observation of an event, such as sleep and breathing, would likely alter that event. PSG in a laboratory setting may disturb the patient enough to give us false-negative measurements.
Like most preliminary studies, this study has some limitations, such as its retrospective nature; however, the authors' finding that more than 80% of patients who were suspected to have OSA, but had a negative PSG, were found to have OSA upon having a repeat HSAT is a pivot point for our field. This report reaches us 25 years after the first case series in which HSAT was used was published.3 Over the past several years HSAT has taken its place as a recognized tool after randomized controlled trials have proven non-inferiority.4,5 The study by Lipatov et al. further supports that key role.
Another key finding of this report is that most patients who were deemed false negative by PSG were in the mild category. Night-to-night variability in recorded REI at home appears to be most significant in the mild category.6 We have good data to guide clinicians on what constitutes a positive diagnosis of OSA, but few data exist to reassure patients when a diagnosis can be ruled out. Clearly a single night in a sleep center or a single night at home appear insufficient to exclude the diagnosis of OSA. Papers like the one by Lipatov et al. truly point out that we need to know much more about our approach to refine best practices and effect efficient care. Should initial testing for OSA be done preferentially in the home? Could more than a single night in the home be an ideal first approach?7 Finally, does making the diagnosis of mild OSA in symptomatic patients really matter?
Alchemists among us have claimed and no doubt will claim that in this scenario, diagnoses provided by HSAT are indeed false positives and further proof of the inferiority of the non-“gold” HSAT. Like our disbelief in alchemy, rational minds cannot accept that repetitive events consisting of absent or diminished airflow with oxygen desaturation are to be ignored. Physics and mathematics are the basis for all science and as such we should abandon beliefs not supported by the data. The field of sleep medicine has clung to the belief in PSG as the gold standard for long enough. Lipatov et al. have provided us compelling data to unseat this belief. Controlled trials of HSAT in those who have a negative PSG are needed along with a re-evaluation of the role of HSAT in value-based disease management.
Perhaps our quest for a gold standard is not a silly dream. As Paulo Coelho tells us in his best seller, The Alchemist, “when you want something, the whole universe conspires to help you.”8 It is time for the sleep field to come together to meld the data and the belief so that a true gold standard can be reached. You may just find that gold standard in your patient's own bedroom.
Dr. Coppola is Executive Vice President and CMO of NovaSom Inc, a national home sleep testing company.
Coppola MP. Physics and alchemy. J Clin Sleep Med. 2018;14(11):1839–1840.
Lipatov K, Hayek A, Ghamande S, Boethel C, Chen W, Jones S. Predictors of obstructive sleep apnea on home sleep apnea test after a negative attended polysomnography. J Clin Sleep Med. 2018;14(11):1889–1894
Uncertainty principle. Encyclopaedia Britannica website. https://www.britannica.com/science/uncertainty-principle. Updated October 5, 2018. Accessed October 8, 2018.
Coppola MP, Lawee M. Management of obstructive sleep apnea syndrome in the home: the role of portable sleep apnea recording. Chest. 1993;104(1):19–25. [PubMed]
Rosen CL, Auckley D, Benca R, et al. A multisite randomized trial of portable sleep studies and positive airway pressure autotitration versus laboratory-based polysomnography for the diagnosis and treatment of obstructive sleep apnea: the HomePAP study. Sleep. 2012;35(6):757–767. [PubMed Central][PubMed]
Kuna ST, Gurubhagavatula I, Maislin G, et al. Noninferiority of functional outcome in ambulatory management of obstructive sleep apnea. Am J Respir Crit Care Med. 2011;183(9):1238–1244. [PubMed]
Prasad B, Usmani S, Steffen AD, et al. Short-term variability in apneahypopnea index during extended home portable monitoring. J Clin Sleep Med. 2016;12(06):855–863. [PubMed Central][PubMed]
Coppola MP. Please, sir, I want some more. J Clin Sleep Med. 2016;12(06):787–788. [PubMed Central][PubMed]
Coelho P, Clarke AR. The Alchemist. New York, NY: HarperOne; 2014.