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. 2024 Mar 1;20(3):461-468.
doi: 10.5664/jcsm.10918.

Large variability in definitions of sleep apnea indices used in clinical studies

Ethan M Balk  1 , Gaelen P Adam  1 , Carolyn M D'Ambrosio  2
Affiliations

Large variability in definitions of sleep apnea indices used in clinical studies

Ethan M Balk et al. J Clin Sleep Med. .

Abstract

Study objectives: We explored the variability of sleep apnea indices and definitions of obstructive sleep apnea in clinical studies of continuous positive airway pressure.

Methods: In a systematic review of the long-term clinical effects of continuous positive airway pressure, we noted variability across studies in how sleep apnea was defined. We, thus, sought to quantify the heterogeneity.

Results: Across 57 comparative studies of long-term clinical outcomes of continuous positive airway pressure, only 40% fully and explicitly reported their definitions of apnea and hypopnea. Most studies defined apnea as 100% airflow cessation, but a minority used 90% or even down to 75% thresholds. Almost half of the studies defined hypopnea as ≥ 50% airflow cessation, but the majority used 30% or even 25% thresholds. Similarly, about half of the studies used a 4% desaturation threshold to define oxygen desaturation and about half used a 3% threshold, with 2 studies using both thresholds for different purposes. Randomized trials were no more consistent or better-reported than observational studies. Studies that cited published criteria generally reported definitions that were different from the cited criteria.

Conclusions: The criteria used to define sleep apnea indices (apnea, hypopnea, and oxygen desaturation) were highly variable, even among studies stating that definitions were based on the same standard criteria. It was often difficult to discern the actual criteria used. The great variability across studies and lack of transparency about their sleep study methods hampers the interpretability and utility of the studies and calls into question whether studies are generalizable from one setting to another.

Citation: Balk EM, Adam GP, D'Ambrosio CM. Large variability in definitions of sleep apnea indices used in clinical studies. J Clin Sleep Med. 2024;20(3):461-468.

Keywords: continuous positive airway pressure device; obstructive sleep apnea; sleep apnea indices; systematic review.

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Conflict of interest statement

All authors have seen and approved the manuscript. This project was funded under contract no. 290-2015-00002-I/75Q80119F32017 from the Agency for Healthcare Research and Quality (AHRQ), US Department of Health and Human Services (HHS). Representatives from AHRQ served as the Contracting Officer’s Technical Representatives and provided technical assistance during the conduct of the full evidence report and provided comments on protocol development and draft versions of the full evidence report. AHRQ did not directly participate in the literature search, determination of study eligibility criteria, data analysis or interpretation, or preparation, review, or approval of the manuscript for publication. The Centers for Medicare and Medicaid Services (CMS) nominated the systematic review to AHRQ, which selected the topic for systematic review by an Evidence-based Practice Center. Representatives from CMS provided extensive input during protocol development and the conduct of the full evidence report and provided comments on draft versions of the full evidence report that formed the basis for this article. CMS did not directly participate in the literature search, determination of study eligibility criteria, data analysis or interpretation, or preparation, review, or approval of the manuscript for publication. Carolyn D’Ambrosio is a triage leader for Dynamed Inc. and holds a patent for a circadian programming device (patent no. 8,979,913). The authors of this article are responsible for its content. Statements in this article do not necessarily represent the official views of or imply endorsement by AHRQ or HHS. The authors report no conflicts of interest.

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