Background: Whether the practical assessment of interstitial pneumonia, such as spirometry, mMRC, or 6-minute walk test, can reflect physical activity in daily life is not clear. We investigated the association of physical activity using ePRO with mMRC, FVC and prognosis in patients with interstitial pneumonia.

Methods: Patients treated or followed for interstitial pneumonia were enrolled and prospectively followed in this study. Physical activities were estimated using amue link (SONY, Tokyo) as an ePRO device for up to 14 days. The measurements were the sum and mean of three estimated values from ePRO, (1) METS, (2) walking distance, and (3) walking steps. The AUC for classification of mMRC or %FVC according to physical activities was estimated by ROC analysis. The prognostic value was also investigated, using the log-rank test for comparisons.  (UMIN000047834)

Results: A total of 53 enrolled patients were analyzed. Among the ePRO measures, mean distance walked (MDW) was identified as a candidate for predicting mMRC and %FVC. The AUC for classification into mMRC ?3 and %FVC?50% based on MDW was 0.810 [95%CI, 0.639 to 0.982] and 0.735 [95%CI, 0.486 to 0.983], respectively. Exploratory analysis showed a significant difference in survival curves based on MDW threshold according to ROC analysis (p=0.027), but survival curves based on mMRC or %FVC were also significantly separated (mMRC, p<0.001; %FVC, p=0.092).

Conclusions: Among the measures of physical activity estimated by amue link, MDW can be an alternative indicator to mMRC or %FVC, with potential to be a prognostic predictor similar to mMRC or %FVC.