Beyond the Apnea–Hypopnea Index: Circulating Biomarkers and Device-Based Metrics for Cardiometabolic Risk Stratification in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is increasingly recognized not merely as a localized anatomical airway disorder, but as a complex systemic condition. While the apnea-hypopnea index (AHI) remains the traditional standard for diagnosis, it possesses inherent limitations in adequately predicting downstream adverse outcomes, necessitating the adoption of novel, comprehensive markers for refined risk stratification. This narrative review summarizes recent evidence on circulating biomarkers and device-based metrics that may complement the AHI for risk stratification in OSA. Beyond traditional metrics, emerging biomarkers in obstructive sleep apnea offer a multifaceted view of the disease, utilizing inflammatory, vascular, metabolic and novel molecular indicators to enhance clinical characterization. These biomarkers reflect key pathophysiological mechanisms, including systemic inflammation, endothelial dysfunction, metabolic imbalance and altered gut microbiota. Commonly studied markers show associations with disease severity and adverse health outcomes. In addition, novel molecular markers, such as microRNAs and advances in sleep study metrics, provide further insight into disease burden, prognosis and cardiovascular comorbidities. A multidimensional framework integrating accessible laboratory markers with device-based metrics may improve identification of patients with OSA who are at highest risk for cardiovascular and metabolic complications.