Obstructive Sleep Apnea in Chronic Obstructive Pulmonary Disease: A Prospective Observational Study

Background: Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) frequently coexist as overlap syndrome a condition associated with severe nocturnal hypoxemia, increased exacerbations, higher cardiopulmonary morbidity and mortality. Despite its clinical impact, overlap syndrome remains underrecognized due to overlapping symptoms and limited routine screening. Objectives: To determine the prevalence of OSA in COPD patients and assess its association with disease severity, exacerbations, hospitalizations and cardiopulmonary outcomes. Methodology: This prospective observational study was conducted in a tertiary care hospital from September to November 2025. A total of 160 stable COPD patients were enrolled and classified into obese (BMI ≥30 kg/m²; n=80) and non-obese (BMI ≤29.9 kg/m²; n=80) groups. All participants underwent clinical evaluation, spirometry, validated questionnaires, echocardiography and overnight polysomnography. OSA was diagnosed using the apnea–hypopnea index. Statistical analysis included nonparametric tests, correlation, and multivariate regression. Results: OSA was identified in 61.9% of patients with moderate-to-severe OSA in 33.7%. Obese patients had significantly higher neck circumference, sleepiness scores and apnea -hypopnea index (p<0.001). OSA was associated with increased exacerbations, hospitalizations, pulmonary hypertension and right ventricular dysfunction. Apnea - hypopnea index correlated positively with body mass index and daytime sleepiness and negatively with FEV₁. Obesity, increased neck circumference, excessive daytime sleepiness and reduced lung function independently predicted moderate-to-severe OSA. Conclusion: OSA is highly prevalent in COPD, particularly among obese patients and is associated with adverse clinical outcomes. Early screening may improve diagnosis and management of overlap syndrome.