The 12-min walk test as an assessment criterion for lung transplantation in subjects with cystic fibrosis☆

Abstract 

Timing for the evaluation and listing of patients with cystic fibrosis who are candidates for lung transplantation is still uncertain. Our study goal was to determine the value of the 12-min walk test as a simple and easy-to-use adjunctive assessment tool for pre-transplant evaluation. A total of 34 cystic fibrosis patients (17 male, mean age 22 years) with end-stage lung disease were evaluated in this retrospective analysis. The 12-min walk test was carried out according to an established protocol. Before walking, body plethysmography was performed and a capillary sample was taken for blood gas analysis. Walking distance and SaO₂ via continuous pulse oximetry were recorded online. There was a strong correlation between survival time and walking distance (r=0.7, P=0.003). No other single parameter, such as FEV₁, SaO_2, pCO₂ or BMI, showed a statistically significant correlation with survival time. Subjects who walked ≤700 m had a lower cumulative survival (P=0.02). There was a statistically significant positive correlation between walking distance and SaO₂ at rest and after 12 min of walking (r=0.5, P=0.001; and r=0.5, P=0.04, respectively). There was no correlation between walking distance and pCO₂ at rest, BMI, FEV₁, or degree of change in SaO₂ during the walk test. This study demonstrates that in CF patients with end-stage lung disease, walking distance during a 12-min walk test is more informative with respect to survival than single parameters such as SaO_2, pCO₂, FEV₁ or BMI.

Keywords: Cystic fibrosis, Lung transplantation, Walk test