Predictive Value of Decreased Pulse Wave Amplitude Index for Cardiovascular

Obstructive sleep apnea (OSA) elevates cardiovascular risk, but existing biomarkers fail to capture sleep-specific hemodynamic changes. This study evaluates the pulse wave amplitude decrease (PWAD) index, a photoplethysmography-derived measure of vascular/autonomic reactivity during respiratory events, in 1,034 OSA patients (AHI ≥ 15). Each 1-unit PWAD increase reduced major adverse cardiovascular events (MACE) risk by 2.6% (HR 0.974, 95%CI 0.953–0.995), with PWAD > 23.5 (median) showing 50.8% risk reduction (HR 0.508, 95%CI 0.291–0.885). The combination of low PWAD (≤ 23.5) and high AHI synergistically increased MACE risk by 116% (HR 2.161, 95%CI 1.049–4.454, P < 0.001) versus double-negative group. Low PWAD correlated with older age, higher LDL, and elevated cardiovascular risk (all P < 0.05), suggesting endothelial dysfunction and autonomic dysregulation as mechanisms. The PWAD index independently predicts cardiovascular risk in OSA and can be automatically measured via standard pulse oximetry, offering a practical tool for identifying high-risk patients needing intensive treatment.​