A 6-minute walk distance (6MWD) is widely used to assess functional exercise capacity in patients with cardiac or pulmonary disease and is known to hold strong prognostic utility. However, previous studies have shown that bodyweight negatively affects the predictive accuracy of the 6MWD. 6-minute walk work (6MWORK = 6MWD X bodyweight) has been shown to be more strongly associated with clinical markers in patients with chronic obstructive pulmonary disease (COPD), however, this has not been investigated in patients with idiopathic pulmonary fibrosis (IPF). This study aims to determine whether 6MWORK has a stronger correlation with clinical parameters compared to 6MWD in male patients with IPF.


Clinical data was retrospectively analyzed from 22 male patients with IPF. Linear correlations between lung function, 6MWORK and 6MWD were performed.


There was a positive correlation between 6MWD and forced expiratory volume in the first second (FEV1) (r=0.488, p=0.021), while a strong positive correlation existed between 6MWORK and FEV1 (r=0.558, p=0.007). There was also a strong positive correlation between 6MWORK and FEV1/forced vital capacity (FVC) ratio (r=0.564, p=0.006), while there was no correlation between 6MWD and FEV1/FVC (r=0.320, p=0.146). Moreover, when performing a linear regression analysis, the FEV1 (β=0.411, p<0.033) and FEV1/FVC (β=0.420, p<0.030) were significant unique contributors to 6MWORK. The model was statistically significant check(R-square=0.47, F(2, 19)=8.31, p<0.003).


6MWORK appears to be more closely associated with clinical parameters in male patients with IPF compared to 6MWD. 6MWORK may better characterize the clinical status of patients with IPF. Further study is needed to investigate the ability of 6MWORK to predict clinical endpoints.

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