Early versus non-early desaturation during 6MWT in COPD patients: A follow-up study

INTRODUCTION: Six-minute walk test (6MWT) has a significant prognostic value in chronic obstructive pulmonary disease (COPD). Those who desaturate early during 6MWT are likely to have frequent exacerbations. AIMS AND OBJECTIVES: To follow-up and compare exacerbations and hospitalisations of COPD patients having early desaturation versus nonearly desaturation determined during baseline 6MWT. METHODS: It was a longitudinal follow-up study conducted in a tertiary care institute from November 1, 2018 to May 15, 2020 involving 100 COPD patients. A decrease in SpO(2) by ≥4% in baseline 6MWT was considered a significant desaturation. If the desaturation occurred within first minute of the 6MWT, the patient was called early desaturator (ED); if it occurred later, the patient was called nonearly desaturator (NED). If the saturation did not fall, then the patient was called nondesaturator. During the follow-up, 12 patients dropped out and 88 remained. RESULTS: Of 88 patients, 55 (62.5%) were desaturators and 33 were nondesaturator. Of 55 desaturators, 16 were ED and 39 were NED. EDs had significantly higher number of severe exacerbations (P <.05), higher hospitalisation (P <.001), and higher BODE index (P <.01) compared to NEDs. The receptor operating characteristic curve and multiple logistic regression analysis showed that previous exacerbations, presence of early desaturation, and distance saturation product during the 6MWT were significant predictors for predicting hospitalizations. CONCLUSION: Early desaturation can be used as a screening tool for assessing the risk of hospitalization in COPD patients.