What defines obstructive sleep apnea in terms of the Apnea-Hypopnea Index (AHI)?

Obstructive sleep apnea (OSA) is defined clinically by the presence of obstructive respiratory events during sleep, characterized by the Apnea-Hypopnea Index (AHI). The AHI measures the number of apneas (complete cessations of breathing) and hypopneas (partial obstructions leading to reduced airflow) that occur per hour of sleep.

An AHI greater than 5 signifies that the individual experiences more than five such episodes per hour, which meets the clinical criteria for diagnosing obstructive sleep apnea. In a clinical context, an AHI of 5 or more is considered indicative of mild OSA, while higher thresholds, such as an AHI greater than 15 or 30, indicate moderate to severe forms of the condition. However, the threshold of 5 is the minimum required to establish the diagnosis of OSA.

Understanding this framework is essential for recognizing how sleep apnea is categorized and the severity of the disorder, as it informs treatment options and management strategies for affected individuals. This makes the AHI a crucial metric in both diagnosis and ongoing evaluation of obstructive sleep apnea.