Apnea-hypopnea index in sleep studies and the risk of over-simplification

Abstract

According to recent reports, sleep disorders affect 30% of the adult population and 5-10% of children. Obstructive Sleep Apnea Hypopnea Syndrome (OSA) has a considerable epidemiological impact and demand for consultation is growing in our community. Therefore, it is necessary to know the principles of interpretation of diagnostic methods. A suspicion of OSA requires confirmation. According to the guidelines of the Argentine Association of Respiratory Medicine, polysomnography (PSG) is the gold standard for OSA diagnosis, while home sleep testing (HST) can be accepted as a comparatively effective method depending on the clinical situation of the patient. This article questions the use of AHI (apnea-hypopnea index) as the only measurement needed to diagnose OSA and assess its severity. In fact, it is surprising that, despite the large mass of data analyzed during sleep studies, current practices only focus on AHI. More than four decades have passed since OSA was first described. Our tendency to oversimplify complex conditions may prevent us from gaining a deeper and more thorough understanding of OSA. The development and validation of OSA severity scoring systems based on multiple parameters is still a pending issue.

Correlates of Endothelial Function in Older Adults With Untreated Obstructive Sleep Apnea and Cardiovascular Disease

“…While AHI remains the basis for the diagnoses and management of OSA, it is not without limitations or controversy. 41–43 Specifically, AHI does not correlate well with excessive daytime sleepiness (EDS) and, when adjusted for other variables, certain clinical manifestations. 42,43 Our finding that AHI was not associated with endothelial function in older adults after adjusting for covariates supports this finding.…”

“…The use of new approaches to assess the severity of OSA, such as the utilization of measures other than AHI like oxygen-desaturation index and the examination of accompanying symptoms and comorbid conditions, may result in improved OSA phenotypes to guide treatment. 41–43 For example, growing evidence supports a no-EDS OSA phenotype. 43 Furthermore, individuals with the no-EDS OSA phenotype may have a different response to PAP compared to individuals with the EDS phenotype.…”

PSG-Audio, a scored polysomnography dataset with simultaneous audio recordings for sleep apnea studies

“…As expected by the prevalence of central apnea syndrome, the frequency of central and mixed apnea episodes is concentrated in the range between 0–5 and 0–20 apneas per sleeping hour, respectively, independently of the severity group in which the patient is classified. The obstructive apnea events represent the major contributor to the final AHI and consequently to the overall diagnosis for the patient 87 , 88 , with the variation in the frequency of appearance resembling the AHI distribution. The hypopnea events of this dataset are particularly frequent in the case of moderately apneic individuals, though such a deduction should also take into account the restricted number of moderate apneic subjects participating in the dataset and it requires further investigation.…”

Preoperative identification of children at high risk of obstructive sleep apnea

“…The severity of OSA is defined as mild if an OAHI is between 1 and 5 (events/h), moderate if the OAHI is between 5 and 10 events/h, and severe if the OAHI is >10 events/h . Snoring without OSA (ie, OAHI <1 event/h) would be considered “primary snoring.” While OAHI is a widely used measure of OSA severity clinically, it has limitations . For example, OAHI only provides a simple count of obstructive episodes per hour of sleep regardless of the duration and the depth of the desaturation or gas exchange abnormality.…”

“…Further, estimation of OSA severity by a limited channel PSG study may underestimate OAHI when based on total recording time (ie, without an EEG‐based measure of sleep), rather than total sleep time . In addition, while home sleep studies are less expensive than in‐lab PSG, they still require the setup of technically complex diagnostic equipment as well as expert interpretation of the acquired data.…”