The correlation between 6-min walk test and respiratory parameters in children with cystic fibrosis

Background: The 6-min walk test (6MWT) is a sub-maximal exercise test and has been widely used for evaluating of exercise capacity of patients with cystic fibrosis (CF) in recent years. Few studies have examined the relationship between 6MWT and parameters used to assess the severity of the disease in children with CF. In this study, we have examined this relationship to find out if 6MWT can be a marker of the severity of cystic fibrosis.

Methods: A cross-sectional study was done to analyze the correlations among spirometry parameters, body mass index (BMI), chest tomography (CT), and 6MWT. CF patients, aged 7-14 years, were involved.

Results: Seventy-six patients, 32F/44M, mean age 10.49 ± 3.18 years, were studied. The mean distance in 6MWT was 447 ± 84.1. The following correlations versus distance were found: FEV1 (r = 0.255, p = 0.026), FVC(r = 0.285, p = 0.013), FEF25-75% (r = 0.546, p < 0.001), BMI (r = 0.163, p = 0.160), and CT (r = 0.075, p = 0.520).The following correlations versus O₂ saturation (SpO₂) decline were found: FEV1 (r = -0.393, p < 0.001), FVC (r = -0.431, p < 0.001), FEF25-75% (r = -0.296, p = 0.010), BMI (r = 0.042, p = 0.721), and CT (r = -0.196, p = 0.090). There was a significant correlation between 6MWT (distance and SpO₂ decline) and pulmonary function test. There was no significant correlation between BMI, chest CT, and 6MWT.

Conclusions: 6MWT can be applied beside spirometry and chest CT for CF patients follow up.