Normal and Abnormal AHI Scores
Understanding AHI Measurement
- The American Academy of Sleep Medicine recommends that an Apnea-Hypopnea Index (AHI) score below 5 events per hour is considered normal, while scores of 5 or above indicate obstructive sleep apnea (OSA) with increasing severity levels 1
- AHI represents the average number of apneas and hypopneas per hour of sleep measured during polysomnography, as defined by the American Academy of Sleep Medicine 1
- Different scoring criteria for hypopneas can significantly affect AHI values and diagnosis thresholds, according to the American Academy of Sleep Medicine 2, 3
AHI Severity Classification
- The American Academy of Sleep Medicine defines a normal AHI as less than 5 events per hour 1
Important Considerations in AHI Interpretation
Scoring Method Variations
- The American Academy of Sleep Medicine notes that different hypopnea definitions can result in substantially different AHI values for the same patient 2, 4
- Using the American Academy of Sleep Medicine-recommended 30% flow reduction with ≥4% oxygen desaturation criteria results in AHI values approximately 70% lower than when using Chicago criteria 2, 3
- An AHI of 5 using the American Academy of Sleep Medicine-recommended criteria would correspond to approximately 10 using the alternative criteria and 15 using Chicago criteria, as reported by the American Academy of Sleep Medicine 2
Population Differences
- The American Academy of Sleep Medicine suggests that AHI interpretation may need adjustment for specific populations, such as lean patients who may have clinically significant hypopneas with minimal desaturation 3
- Adolescents scored using adult criteria may have significantly lower AHI values than when scored using pediatric criteria, according to the American Academy of Sleep Medicine 3
- Different scoring methods can result in significantly different diagnosis rates, especially in borderline cases, as noted by the American Academy of Sleep Medicine 2, 4