Authors: Ana Florica Chiș1,2, Ruxandra Mioara Râjnoveanu1,2, Milena Adina Man1,2, Doina Adina Todea1,2, Bogdan Augustin Chiș1, Carmen Monica Pop1,2
¹ “Iuliu Hațieganu” University of Medicine and Pharmacy, Department of Pneumology, Cluj-Napoca, Romania
² “Leon Daniello” Clinical Hospital of Pneumology, Cluj-Napoca, Romania
Background. In Chronic Obstructive Pulmonary Disease (COPD) patients, Six-Minute Walk Test (6MWT) represents a validated tool in evaluating the functional status.
Aims. Our study aims to establish the role of demographic features, COPD degree of severity and risk groups in the 6MWT results.
Methods. We conducted a randomized study on 60 COPD patients without major comorbidities, admitted to the “Leon Daniello” Clinical Hospital of Pneumology, Cluj-Napoca. We collected data regarding age, gender, Body Mass Index (BMI), smoking history, and we performed the 6MWT in accordance with the American Thoracic Society (ATS) guidelines. The investigated parameters of the effort capacity test were: the distance (meters), the percentage of the predicted values of 6MWT and the SpO2 (peripheral blood oxygen saturation) decrease.
Results. The BMI correlated with the number of years since smoking cessation (p=0.04, r=0.26). The walking distance decreased with higher severity stages (383.8±68.3 meters in stage 2 COPD versus 212.8±83.1 meters in stage 4 of the disease, p<0.0001). SpO2 decreased more in stage 4 (4%±0.6) than in stage 3 (2.6%±1.2) and stage 2 of COPD (1.6%±1.2) (p<0.001, F=18.560). When evaluating the outcomes of the 6MWT based on the risk group of COPD (A to D), we found correlations between the risk group and the walked distance (p=0.001), the percentage of the predicted value of the test (p=0.009), and the desaturation index (p<0.0001). No correlation was found between the outcomes of the 6MWT and gender, age, smoking history (p>0.05).
Conclusions. 6MWT is influenced by the COPD risk group, disregarding age or the smoking history, in the absence of comorbidities; thus, it could be used as a tool in the staging and monitoring of the evolution of the disease. BMI in COPD patients is positively correlated with the number of years since smoking cessation.
Keywords: COPD, smoking, obesity, Six-Minute Walk Test.