Criteria for Diagnosing the Severity of Obstructive Sleep Apnea (OSA)

Diagnostic Parameters

The American Academy of Sleep Medicine defines OSA severity as mild for Respiratory Disturbance Index (RDI) ≥ 5 and < 15, moderate for RDI ≥ 15 and ≤ 30, and severe for RDI > 30/hr 1
OSA is diagnosed when the Apnea-Hypopnea Index (AHI) is ≥ 5 events per hour with associated symptoms or when AHI ≥ 15 regardless of symptoms 1
AHI is calculated as the sum of apneas and hypopneas per hour of sleep 2, 3
Respiratory Disturbance Index (RDI) may include respiratory effort-related arousals (RERAs) in addition to apneas and hypopneas 1

Portable monitoring (PM) should include at minimum: airflow, respiratory effort, and blood oxygenation, and should be performed under the auspices of an accredited sleep medicine program 1
The American Academy of Sleep Medicine recommends that portable monitoring be used as an alternative for patients with high pre-test probability 1

Severity classification guides treatment decisions and predicts health outcomes, according to the American Academy of Sleep Medicine 1
The American Academy of Sleep Medicine suggests that while AHI/RDI thresholds provide standardized criteria for OSA severity, the clinical significance should be interpreted in the context of symptoms, comorbidities, and other physiological parameters for optimal patient management 1