eAHI Interpretation Guidelines

Diagnostic Criteria

The American Academy of Sleep Medicine defines normal diagnostic AHI as <5 events/hour, while OSA diagnosis requires AHI ≥5 with symptoms or ≥15 without symptoms 2, 3, 4
Mild OSA is characterized by an AHI of 5-14 events/hour, according to the American Academy of Sleep Medicine 1, 2
Moderate OSA is defined as an AHI of 15-29 events/hour by the American Academy of Sleep Medicine 1, 2
Severe OSA is indicated by an AHI ≥30 events/hour, as defined by the American Academy of Sleep Medicine 1, 2

The American Academy of Sleep Medicine suggests that an eAHI cutoff of 6-8 events/hour can distinguish adequately treated patients from those with residual obstructive sleep apnea, although the exact cutoff may vary depending on the study 1, 2
An eAHI >6 events/hour may indicate residual sleep-disordered breathing, requiring clinical evaluation and possible CPAP adjustment, as recommended by the American Academy of Sleep Medicine 2
For detecting more severe residual OSA (PSG AHI ≥10), an eAHI cutoff of 8 events/hour provides optimal accuracy with sensitivity 0.94 and specificity 0.90, according to the American Academy of Sleep Medicine 2

eAHI cannot detect arousals since auto-CPAP devices lack EEG monitoring, potentially underestimating sleep fragmentation compared to polysomnography, as noted by the American Academy of Sleep Medicine 3, 5
The American Academy of Sleep Medicine recommends that patients with persistent symptoms despite eAHI <6 require full polysomnography to assess for arousal-based events (RERAs), central apneas, or other sleep disorders not captured by CPAP algorithms 3, 5
Scoring method variations significantly affect interpretation, with different hypopnea definitions altering AHI values by up to 70%, although this primarily affects diagnostic rather than treatment monitoring, as reported by the American Academy of Sleep Medicine 4

The American Academy of Sleep Medicine suggests that for patients on auto-CPAP therapy with eAHI >6 events/hour or persistent symptoms, clinicians should check for excessive mask leak, inadequate pressure settings, and poor adherence patterns, and consider in-laboratory PSG on CPAP to assess for residual events, arousals, or alternative diagnoses 2, 3
The American Academy of Sleep Medicine recommends that an eAHI >8 events/hour indicates a high likelihood of significant residual OSA requiring intervention 2, 3

The American Academy of Sleep Medicine notes that eAHI accuracy was validated in patients with varying OSA severity, supporting its use across the disease spectrum, although it may miss arousal-predominant disease 5, 6
The American Academy of Sleep Medicine reports that Bland-Altman analysis demonstrates good agreement between auto-CPAP eAHI and polysomnography AHI, with a positive likelihood ratio of 9.6 for detecting residual disease, although the exact value may vary depending on the study 5, 6