Subjects who withdrew from the study and/or did not provide full accelerometry data had lower diffusion capacity and we cannot explain this. In our post hoc analysis, we found no clear relationship between diffusion capacity and PA. The observed negative relationship between baseline diffusion capacity and LPA is not consistent with clinical expectations. Still, the positive relationship between baseline diffusion capacity and change in LPA is reasonable since the combined groups had a decline in LPA. It suggests that subjects who started with a lower diffusion capacity experienced a greater decline in LPA.