COPD Patients with Exertional Desaturation Are at a Higher Risk of Rapid Decline in Lung Function

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 (SpO(2)) 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 SpO(2) of <90% during the 6MWT. Rapid decline was defined as an annual rate of decline in forced expiratory volume in 1 second (FEV(1)) ≥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 FEV(1). 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.