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Nov 74 min read

3. Latest Real World Evidence -Obstructive (OSA) and co-existing Central and Obstructive sleep apnea (CSA-OSA) phenotypes in real-world data


In blog 2 of this series we explored the current understanding of OSA and CSA reported prevalence, software management detection of these events and tailoring treatment parameters based on remote monitoring data. In this 3 rd. blog of these series we want to share with you the results of this "Real World Study" by Key Opinion Leader's (KOL's) Pepin et al 2024 1.


The prevalence of CSA in our previous blog was reported to be 5-10% in the ERJ by Randerath et al 2024, however, the authors acknowledged that the prevalence of CSA may be underestimated as epidemiological data are largely based on the AASM reporting criteria 2.


This large real world study was conducted in > 2400 patients referred with suspicion of sleep apnea. The authors systematically distinguished central versus obstructive hypopneas to define OSA, CSA and coexisting CSA-OSA. Their results report that when CSA was defined by the proportion of central apneas (and hypopneas were considered obstructive by default), the prevalence of CSA was 4.59 % (co-existing CSA-OSA: 11.03 %, and OSA: 84.37 %).

When the distinction between obstructive and central hypopneas was used to classify the sleep disordered breathing, the prevalence of CSA was fourfold higher at 19.69 %, indicating that 1 in 5 of these individuals may have CSA, which is a higher prevalence than previously reported. This raises the issue of how important is this for sleep medicine clinicians and how they manage residual central hypopnoeas in their patients.

Pepin et al 2024 highlight crucial differences between reporting of CSA, OSA, and the combined condition CSA-OSA. Does this research, based on a large real-world patient dataset, underscore the importance of accurately differentiating central and obstructive hypopneas during polysomnography (PSG) scoring?

Then following on from this, when patients commence CPAP therapy with remote monitoring, current devices vary significantly on their reporting of residual central apnoeas and hypopnoeas as has been shown by Lebret et al at the ERS 2024, who found that only a limited number of devices were able to categorise hypopnoeas with poor detection of central hypopnoea in the four of the five CPAP devices tested (Article in Press).


The differences between CPAP device reporting central apnoea and hypopnoeas may be explained by different algorithms present in various manufacturers devices. "Is what is being reported what is actually happening in real life". Do all therapy devices detect and report central apnoea and hypopnoeas?


Graphical abstract of Pepin et al 2024 show that OSA and CSA are treated differently highlighting that CSA have a higher burden of comorbidities.


These findings may have implications for manufacturers of sleep apnoea devices and sleep clinicians. Firstly, CPAP/APAP device algorithms report residual central apnoea and hypopnoeas differently as has been demonstrated in a recent study by Midelet et al 2021 in 3102 patients 3. and the Lebret et al 2024 study ( In Press). Midlet et al 2021 found that the residual AHI reported by one CPAP brand was significantly lower than the residual AHI reported by other CPAP brands. They confirmed that statistically significant differences exist between CPAP brands when reporting residual AHI (Including central hypopnoeas) and this discrepancy may be clinically relevant in a subgroup of individuals. The recent data presented by Lebret et al 2024 (In Press) also found wide variation between devices reporting residual central apnoea and hypopnoeas.


A recent publication by Kundel et al 2024 provides and expert panel review on CSA. The panel emphasises the need for comprehensive studies on the clinical implications of CSA, distinguishing between central and obstructive hypopneas, and developing standardised diagnostic protocols. They advocate for improved endo-phenotyping and further research on combination therapies and nocturnal supplemental oxygen, along with comparative effectiveness trials to enhance therapeutic outcomes in CSA 4.


Clinicians should consider CPAP/APAP devices that accurately report residual central apneas and hypopneas, as highlighted by Pepin et al's study. A nuanced treatment approach is necessary, considering sleep apnea type, comorbidities, and patient experiences. The study advocates for precise, personalised diagnosis and management of sleep apnea 1.


Modern CPAP devices provide advanced features like improved event detection, accurate leakage compensation, refined event classification, automatic pressure adjustments, and remote monitoring for more precise management. They can detect subtle breathing irregularities and optimise therapy automatically. The issue lies not in technological capability but in consistent clinical implementation. Finally, recently published French recommendations suggest that CPAP devices censoring central events and/or reports censoring central hypopneas should not be used in patients with central events on the initial diagnostic test 5.



In blog 4 of these series we will discuss that CSA is more prevalent in the real-life setting.  Pepin et al 2024 exposes a significant disconnect: we possess the technology to precisely diagnose different types of sleep apnea, yet we aren't consistently using it. This can lead to a significant undercounting of CSA, a condition often misdiagnosed as OSA or a mixed apnea type. This misdiagnosis may have clinical consequences, as treatment effectiveness may vary significantly in people with CSA phenotypes.






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