a. Distribution of CAT scores by DLco category. Mantel-Haenszel test was used to test for a linear trend between CAT scores and DLco category [Ptrend Ptrend b. Distribution of SGRQ scores by DLco category. Kruskal-Wallis test was used to test for a linear trend between SGRQ scores and DLCO category [Ptrend Ptrend < 0.001 (**)].</p