The asthma-obstructive sleep apnea overlap: pathophysiological links, clinical impact, and implications for integrated management

The asthma-obstructive sleep apnea (OSA) overlap is a clinically important phenotype, especially in patients with severe or difficult-to-control asthma. Rather than a simple coexistence of independent conditions, this overlap represents a distinct clinical entity modulated by shared pathobiological pathways. This review integrates epidemiologic data, critically balancing association and causation across shared risk factors (obesity, GERD, upper airway disease). We construct an integrated mechanistic framework encompassing mechanical/neuroreflex interactions, intermittent hypoxia–driven inflammation/oxidative stress, and metabolic dysfunction. The overlap is associated with poorer asthma control, increased nocturnal symptoms, reduced quality of life, and higher healthcare utilization. Current evidence is largely observational; randomized controlled trials with respiratory endpoints and prospective cohorts with repeated polysomnography and biomarker panels are needed to establish strict bidirectional causality and identify responders to targeted therapies. A multidisciplinary, treatable-traits approach addressing OSA, obesity, rhinitis, GERD, and inhaler optimization is recommended while awaiting mechanistic and interventional data on CPAP, weight-loss therapies, and biologics.