AHI severity scale for adult sleep apnea
The apnea-hypopnea index (AHI) is the average number of apneas and hypopneas per hour of sleep. The American Academy of Sleep Medicine grades adult obstructive sleep apnea by AHI as below.
| Severity | AHI (events per hour) |
|---|---|
| Normal | Fewer than 5 |
| Mild OSA | 5 to 15 |
| Moderate OSA | 15 to 30 |
| Severe OSA | More than 30 |
Notes
- The AASM fact sheet writes the bands as 5 to 15, 15 to 30 and more than 30, so the exact boundary values are assigned slightly differently by different sources.
- Severity on a diagnostic sleep study is different from the residual AHI your CPAP reports during treatment. A residual AHI that stays high is something to raise with your clinician.
- Medicare covers CPAP when the AHI or RDI is 15 or more (with at least 30 events), or 5 to 14 (with at least 10 events) plus documented symptoms such as excessive daytime sleepiness, or conditions such as hypertension, ischemic heart disease or history of stroke.
- Medicare's hypopnea definition requires a 4% oxygen drop; scoring rules that accept a 3% drop or an arousal can produce a higher AHI for the same night.
- These bands apply to adults. Children are assessed with different criteria.
Sources
More reference tables
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