Clinical Determinants of the Six-Minute Walk Test (6MWT) in Stable Non-Cystic Fibrosis Bronchiectasis Patients

Abstract

BACKGROUND: The six-minute walk test (6MWT) is a suitable tool for the assessment of functional capacity in patients with chronic pulmonary diseases. This study aimed to assess the clinical determinants of the six-minute walk distance (6MWD), exercise-induced desaturation (EID), and pretest saturation of arterial oxygen (Sat(a)O(2)) in patients with diffuse non-cystic fibrosis (CF) bronchiectasis. MATERIALS AND METHODS: In this cross-sectional study, a total of 57 clinically stable patients with diffuse non-CF bronchiectasis were enrolled. Anthropometric measurements (body mass index BMI, mid-arm muscle circumference MAMC, and triceps skinfold thickness TSF), spirometric indices (forced expiratory volume in one second FEV1, forced vital capacity FVC, and FEV1/FVC ratio), imaging assessment (CT scan), and bacteriological sputum studies were performed, and then, 6MWT was carried out. RESULTS: The mean 6MWD was measured to be 447.11±94.59 m. The average walked distance in patients with severe, moderate, and mild bronchiectasis was 427.73±92.07, 439.63±102.65, and 485.87±80.47 m, respectively, with no significant difference. The pretest Sat(a)O(2) was 88.92±5.59%, 93.75±3.36%, and 94.87±2.88% in the severe, moderate, and mild bronchiectasis groups (P<0.001). A significant inverse correlation was observed between the distance walked and BMI (r=-0.434, P=0.001). CONCLUSION: The predictors of 6MWD in stable non-CF bronchiectasis patients were FVC, Sat(a)O(2) at rest, BMI, and MAMC. The FEV1, FEV1/FVC, and BMI were independent predictors of Sat(a)O(2) at rest. The extension of bronchiectasis was the only predictor of EID during the test.