A comparative assessment of the relationship between measurements made in an incremental shuttle walk test and an incremental cycle ergometry test in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) causes lung function decline, exercise limitation and ultimately death. The rate of disease progression is variable but accurate prognosis aids clinical management. Cardiopulmonary exercise testing (CPET) is the gold standard prognostic test for IPF; peak oxygen consumption (VO2 peak) and blood oxygen (PO2) at peak exercise are known to be good indicators of prognosis. However, CPET is not routinely used to assess IPF. Incremental shuttle walk testing (ISWT) is quicker, cheaper and more widely available than CPET. Our previous work found a statistically significant relationship between distance walked in an ISWT (ISWTD) and VO2 peak during CPET in patients with IPF. Disease-related functional impairment has limited recruitment. Patients with a confirmed diagnosis of IPF were asked to undertake each test after which a blood gas sample was measured and a questionnaire was completed. Six participants have completed both tests. Interim analysis indicates no difference between the VO2 peak-ISWTD relationships in this study and the previous one. Therefore provisional results support a positive and reproducible relationship between VO2 peak and ISWTD. This suggests that ISWT could be used more widely to assess patients with IPF in order to improve prognostic predictions and patient care.