RT Journal Article
SR Electronic
T1 Interpretation of treatment changes in 6-minute walk distance in patients with COPD
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP 637
OP 643
DO 10.1183/09031936.00140507
VO 32
IS 3
A1 M. A. Puhan
A1 M. J. Mador
A1 U. Held
A1 R. Goldstein
A1 G. H. Guyatt
A1 H. J. Schünemann
YR 2008
UL http://erj.ersjournals.com/content/32/3/637.abstract
AB There is uncertainty about the interpretation of changes in the 6-min walk distance (6MWD) in chronic obstructive pulmonary disease (COPD) patients and whether the minimal important difference (MID) for this useful outcome measure exists. Data were used from nine trials enrolling a wide spectrum of COPD patients with 6MWD at baseline and follow-up and used to determine threshold values for important changes in 6MWD using three distribution-based methods. Anchor-based methods to determine a MID were also evaluated. Data were included of 460 COPD patients with a mean±sd forced expiratory volume in one second (FEV1) of 39.2±14.1% predicted and 6MWD of 361±112 m at baseline. Threshold values for important effects in 6MWD were between 29 and 42 m, respectively, using the empirical rule effect size and the standardised response mean. The threshold value was 35 m (95% confidence interval 30–42 m) based on the standard error of measurement. Correlations of 6MWD with patient-reported anchors were too low to provide meaningful MID estimates. 6-min walk distance should change by ∼35 m for patients with moderate to severe chronic obstructive pulmonary disease in order to represent an important effect. This corresponds to a 10% change of baseline 6-min walk distance. The low correlations of 6-min walk distance with patient-reported anchors question whether a minimal important difference exists for the 6-min walk distance.