Purpose: A recent study demonstrated that exertional desaturation is a predictor of rapid decline in lung function in patients with chronic obstructive pulmonary disease (COPD); however, the study was limited by its method used to detect exertional desaturation. The main purpose of this study was to explore whether exertional desaturation assessed using nadir oxygen saturation (SpO₂) during the 6-minute walk test (6MWT) can predict rapid lung function decline in patients with COPD.
Materials and methods: A retrospective analysis was performed on 57 patients with moderate to very severe COPD who underwent the 6MWT. Exertional desaturation was defined as a nadir SpO₂ of <90% during the 6MWT. Rapid decline was defined as an annual rate of decline in forced expiratory volume in 1 second (FEV₁)≥50 mL. Patients were divided into rapid decliner (n=26) and non-rapid decliner (n=31) groups.
Results: A statistically significant difference in exertional desaturation was observed between rapid decliners and non-rapid decliners (17 vs. 8, p=0.003). No differences were found between the groups for age, smoking status, BODE index, and FEV₁. Multivariate analysis showed that exertional desaturation was a significant independent predictor of rapid decline in patients with COPD (relative risk, 6.8; 95% CI, 1.8 to 25.4; p=0.004).
Conclusion: This study supports that exertional desaturation is a predictor of rapid lung function decline in male patients with COPD.
Keywords: Chronic obstructive pulmonary disease; exercise; hypoxemia; lung function.