Exercise-Induced Desaturation in COPD Patients Postexacerbation: Impact of Different Definitions on Prevalence Rates...

Exercise-induced oxygen desaturation (EID) refers to a significant decrease in oxygen saturation (SpO₂) during physical exertion, commonly observed in chronic obstructive pulmonary disease (COPD) patients. Definitions of EID vary widely between studies, leading to difficulties in comparing results and inconsistencies in clinical practice.

The objectives of this study were to evaluate (a) the different definitions of EID reported in the literature, (b) the prevalence of EID during the 6-min walking test (6MWT) in a cohort of COPD patients undergoing pulmonary rehabilitation (PR), and (c) the agreement between the definitions.

A scoping review was conducted to assess existing EID definitions. The prevalence of EID in a cohort of postexacerbation COPD patients performing the 6MWT at admission to PR was retrospectively evaluated based on selected definitions. Agreement between definitions was assessed using Fleiss' kappa.

Of the 244 articles reviewed, 62 met the inclusion criteria, and 23 definitions of EID were identified. The seven most cited definitions found were applied to 954 patients who completed the 6MWT at admission. The most common criterion was a ≥ 4% decrease in SpO₂ during walking. The prevalence of EID varied between 15.6% and 38.7% depending on the criterion used. The overall agreement between the definitions was good, with a Fleiss kappa of 0.718.

In a large COPD cohort recovering from exacerbation, EID prevalence varied significantly depending on the definition used. Although good agreement was found between the criteria, the most conservative definition identified EID in only 15% of patients. Future studies will be necessary to determine which definition is most appropriate, predictive for outcomes, and useful for prescribing oxygen under effort.