PFT trajectory improves on pirfenidone. This figure illustrates the changes in spirometry metrics over time, comparing data from 24 months before the trial to measurements after starting pirfenidone. Red circles represent pretreatment values, and blue circles represent values while on pirfenidone. A regression line is fitted to the aggregate data, with the gray band indicating the 95% confidence interval. (A) ppFEV₁ over time for all participants on pirfenidone (P = .00267). (B) ppFVC over time for all participants on pirfenidone (P = .170). (C) ppFEV₁ over time for responders to pirfenidone (P = .060). (D) ppFVC over time for responders to pirfenidone (P = .122). Regression line equations display intercept and slope.