PT  - JOURNAL ARTICLE
AU  - Holland, Anne E
AU  - Hill, Catherine J
AU  - Dowman, Leona
AU  - Glaspole, Ian
AU  - Goh, Nicole
AU  - Lee, Annemarie L
AU  - McDonald, Christine F
TI  - Short- and Long-Term Reliability of the 6-Minute Walk Test in People With Idiopathic Pulmonary Fibrosis
AID  - 10.4187/respcare.05875
DP  - 2018 Jun 26
TA  - Respiratory Care
PG  - respcare.05875
4099  - http://rc.rcjournal.com/content/early/2018/06/26/respcare.05875.short
4100  - http://rc.rcjournal.com/content/early/2018/06/26/respcare.05875.full
AB  - BACKGROUND: The aim of this work was to investigate the short- and long-term test-retest reliability of the 6-min walk distance (6MWD), peak heart rate, and nadir oxygen desaturation in idiopathic pulmonary fibrosis (IPF).METHODS: A reliability study of 70 adults with IPF was undertaken within out-patient pulmonary rehabilitation programs at 2 tertiary hospitals. Participants completed 2 baseline 6-min walk tests using a standard protocol, with continuous measures of percutaneous SpO2 and heart rate via pulse oximetry. The 6-min walk test was completed immediately following an intervention period and 6 months after. Reproducibility was assessed by intraclass correlation coefficient and Bland-Altman analysis.RESULTS: Participants with a mean ± SD diffusing capacity of the lung for carbon monoxide of 48 ± 14% were included. The reliability of the 6MWD was high (intraclass correlation coefficient = 0.96) with a mean learning effect of 21 m (95% CI 12-30 m). The learning effect persisted at 8 weeks (mean 14 m, 95% CI 5-23 m) but not 6 months (mean 15 m, 95% CI −1 to 30 m). Using the best (greatest) 6MWD significantly reduced the proportion of participants who were classified as having a clinically important response to rehabilitation compared with using the first 6MWD (40% vs 54%, P = .002). Nadir SpO2 was reproducible, with a mean difference of 0.7 ± 2.2%, and limits of agreement of −4 to 5%. Peak heart rate was more variable, with mean difference 5 ± 9 beats/min and limits of agreement of −12 to 20 beats/min.CONCLUSIONS: The 6MWD is a reproducible measure of exercise capacity in people with IPF. Whereas the nadir SpO2 may be accurately determined from one test, evaluating change in 6MWD with interventions may require 2 tests on each occasion.