Validity of the 6-Minute Walk Test in Patients with End-Stage Lung Diseases Wearing an Oronasal Surgical Mask in Times of the COVID-19 Pandemic

Background and Objectives: The 6-minute walk test (6MWT), as a clinical assessment tool for functional exercise capacity, is an integral component of lung allocation scores (LASs). In times of the coronavirus disease (COVID-19) pandemic, patients underwent 6MWTs wearing a surgical mask in ambulatory care. We investigated the impact of wearing a mask on 6-minute walk distances (6MWDs). Method: 6MWDs of 64 patients with end-stage lung diseases wearing an oronasal surgical mask were retrospectively compared to previously investigated 6MWDs of the same cohort, in a pre-COVID-19 pandemic era, without wearing a mask. Four patients were excluded due to a primary vascular disease, 29 patients due to clinically unstable pulmonary functions, and 1 patient due to a psychiatric disorder. Results: The median age of the patients included was 55 (46-58) years; 15 (48%) were male. Ten (32.2%) were on the Eurotransplant lung transplant waiting list with a median LAS of 34.3 (31.9-36.2). Twenty (64.5%) patients had chronic obstructive pulmonary diseases, 7 (22.6%) had interstitial lung diseases, and 4 (12.9%) had other end-stage lung diseases. The mean 6MWD without versus with wearing a mask was 306.9 (101.9) versus 305.7 (103.8) m, with a mean difference of -1.19 m (95% confidence interval -13.4 to 11.03). The observed difference is statistically equivalent to zero (p < 0.001). No significant differences in 6MWDs were observed between the clinical groups. Conclusion: Wearing an oronasal surgical mask did not affect the 6MWDs of patients with advanced lung diseases. Therefore, a masked 6MWT appears to provide a reliable examination of functional exercise capacity in this cohort.