Small changes in six-minute walk distance are important in diffuse parenchymal lung disease.
The aim of this study was to determine the minimal important difference for the six-minute walk distance in people with diffuse parenchymal lung disease.


METHODS
Forty-eight subjects (24 idiopathic pulmonary fibrosis) undertook the six-minute walk test before and after an 8-week exercise program. The minimal important difference was calculated using a distribution-based and an anchor-based method. A global rating of change scale was used as the external criterion to judge patients as clinically unchanged or changed.


RESULTS
The mean change in six-minute walk distance in improved subjects was 50.0 m, compared to 4.0 m in unchanged subjects and a reduction of 64.3 m in those classified as worse (p<0.001). The receiver operating characteristic curve indicated a cut-off value for meaningful change of 30.5 m (area under the curve 0.89, 95% confidence interval 0.81-0.98) whilst the standard error of the mean method indicated a value of 33 m. Similar values were obtained when only subjects with idiopathic pulmonary fibrosis were included (29 and 34 m, respectively).


CONCLUSIONS
Small differences in six-minute walk distance, in the range 29-34 m, may be clinically significant for people with diffuse parenchymal lung disease.
Holland
Anne E
AE
School of Physiotherapy, La Trobe University, Bundoora 3086, Australia. a.holland@alfred.org.au
Hill
Catherine J
CJ
Conron
Matthew
M
Munro
Prue
P
McDonald
Christine F
CF
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D019540:Area Under Curve; D005080:Exercise Test / Q000379:methods; D005081:Exercise Therapy; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D013997:Time Factors; D016138:Walking / Q000502:physiology*