# Efficacy of antifibrotic treatment for ANCA-positive fibrosing interstitial lung disease: a retrospective case‒control study

## TL;DR

This study found that adding antifibrotic drugs to treatment for a specific lung disease (ANCA-fILD) may help preserve lung function without increasing side effects.

## Contribution

This is the first large-scale retrospective case-control study to evaluate antifibrotic treatment in ANCA-positive fibrosing interstitial lung disease.

## Key findings

- Add-on antifibrotic therapy significantly slowed the decline in vital capacity and diffusion capacity over one year.
- No significant differences in adverse events or acute exacerbations were observed between groups.
- The study is the first large-scale analysis to examine antifibrotic use in ANCA-fILD with baseline FVC%pred matching.

## Abstract

Studies verifying the performance of antifibrotic drugs for the treatment of ANCA positive fibrotic ILD (ANCA-fILD) are lacking.

This study assessed the clinical features of ANCA-fILD patients with or without add-on treatment with antifibrotic drugs. A retrospective study involving ANCA-positive patients treated from January 2012 to December 2023 at Peking Union Medical College Hospital was conducted, and a case‒control analysis was performed accordingly.

A total of 105 ANCA-fILD patients were identified from 18,617 ANCA-positive patients treated from January 2012 to December 2023 at Peking Union Medical College Hospital; these patients were further divided into an add-on group (31 patients) and a non-add-on group (74 patients). On the basis of baseline FVC%pred matching (± 10%), 30 and 60 patients were ultimately included in the add-on and non-add-on groups, respectively. The decreases in pFVC (p = 0.03), FVC (p = 0.02), DLCO (p = 0.01), and pDLCO (p < 0.01) were less significant in the add-on group than in the non-add-on group. In the related sample analysis, the add-on group did not present significant differences in FVC (p = 0.47), pFVC (p = 0.53), DLCO (p = 0.90), and pDLCO (p = 0.43) between baseline and at the end of the 1-year follow-up, whereas the non-add-on group presented significant decreases in FVC (p < 0.01), pFVC (p < 0.01), DLCO (p < 0.0001) and pDLCO (p < 0.0001). The incidence rates of adverse events and acute exacerbations were similar between the two groups.

Add-on antifibrotic medications seem to effectively slow the deterioration of lung function in patients with ANCA+ fILD without causing any obvious new-onset adverse reactions.

The online version contains supplementary material available at 10.1186/s12890-026-04109-1.

1) Preserved lung function: add-on antifibrotic therapy significantly attenuated the decline in vital capacity and diffuse function over 1 year compared to the non-add-on group.

2) Safety Profile: No significant differences in adverse events or acute exacerbations were observed between groups, supporting the safety of antifibrotics in ANCA-fILD.

3) Clinical Relevance: This is the first large-scale retrospective analysis (n = 105) to specifically examine antifibrotic use in ANCA-fILD, with case-control matching for baseline FVC%pred.

The online version contains supplementary material available at 10.1186/s12890-026-04109-1.