Nocturnal Hypoxemia As A Marker Of Disease Severity In Chronic Obstructive Pulmonary Disease: A Cross-Sectional Study

Abstract

Background: Nocturnal oxygen desaturation (NOD) is a common but underrecognized phenomenon in chronic obstructive pulmonary disease (COPD), contributing to disease progression and adverse clinical outcomes. Its association with disease severity and clinical predictors remains inadequately explored in resource-limited settings. Methods: A hospital-based cross-sectional analytical study was conducted from August 2025 to January 2026 among 100 clinically stable COPD patients. Data on demographic and clinical variables were collected, and COPD severity was classified using GOLD criteria. Nocturnal oxygen desaturation was assessed using overnight pulse oximetry, while exercise-induced desaturation was evaluated using the six-minute walk test (6-MWT). Statistical analysis was performed using SPSS version 26.0. Associations were assessed using chi-square test, and predictors were identified using univariate and multivariate logistic regression. Results: The prevalence of nocturnal oxygen desaturation was 58%. NOD increased significantly with COPD severity, from 16.7% in GOLD I to 90.9% in GOLD IV (p<0.001). On multivariate analysis, independent predictors of NOD included age >60 years (AOR 1.8, p=0.03), smoking (AOR 2.6, p=0.004), BMI <18.5 kg/m² (AOR 2.1, p=0.02), COPD duration ≥5 years (AOR 1.9, p=0.04), GOLD stage III–IV (AOR 3.5, p<0.001), and 6-MWT desaturation (AOR 5.2, p<0.001). Conclusion: Nocturnal oxygen desaturation is highly prevalent in COPD and strongly associated with disease severity and key clinical factors. Early identification using simple screening tools such as pulse oximetry and 6-MWT may facilitate timely intervention and improve clinical outcomes.