What is the primary difference between the Respiratory Disturbance Index (RDI) and the Apnea-Hypopnea Index (AHI)?

The primary difference between the Respiratory Disturbance Index (RDI) and the Apnea-Hypopnea Index (AHI) lies in the components that each index includes. The RDI includes apneas, hypopneas, and respiratory effort-related arousals (RERAs), which are brief interruptions in breathing that lead to an arousal from sleep, even if they are not full apneas or hypopneas. This means that RDI provides a broader assessment of respiratory disturbances during sleep by factoring in these additional events that can affect sleep quality and overall health.

On the other hand, the AHI is more focused and only takes into account apneas and hypopneas, thus offering a narrower perspective on sleep-disordered breathing. By incorporating RERAs, the RDI reflects a more comprehensive picture of how respiratory disturbances can disrupt sleep, making it particularly valuable in assessing patients who experience these subtle disruptions.

The understanding of this difference is critical in clinical practice as it can influence diagnosis and treatment decisions for individuals experiencing sleep-related conditions.