Abstract
Background: Analysis of data from the GIPF-007 trial of IFNγ-1b suggested that FVC decline may be confounded by the extent of emphysema (EE) on HRCT in patients with IPF. IPF progression may, therefore, not be captured using FVC. This finding was further investigated in a combined analysis of data from the GIPF-007 trial and another IFNγ-1b trial, GIPF-001.
Methods: The study sample included 455 patients from GIPF-001 and -007. EE and extent of fibrosis were assessed on HRCT. The relationship between EE (no emphysema/EE <15% vs EE ≥15%), fibrosis extent and ΔFVC (baseline to Week 48) was evaluated within a bivariate and multivariate framework, with the latter controlling for potential differences in age, gender, smoking status, FVC, FEV1 and DLco at baseline.
Results: 281 patients (61.8%) did not have evidence of emphysema on HRCT. Among 174 patients with evidence of emphysema, 56 (12.3%) had EE ≥15% and 118 (25.9%) had EE <15%. In bivariate analysis, mean decline in absolute FVC (% predicted) over 48 weeks was 0.7% in patients with EE ≥15% vs 4.0% in patients with no emphysema or EE <15% (p=0.037). In multivariate analysis, EE ≥15% and fibrosis were found to be significant predictors of ΔFVC (Figure).
Conclusion: Patients with IPF and EE ≥15% had, on average, less decline in FVC over 48 weeks than those with no emphysema or EE <15%.
- Copyright ©the authors 2016