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

Abstract Introduction Studies verifying the performance of antifibrotic drugs for the treatment of ANCA positive fibrotic ILD (ANCA-fILD) are lacking. Materials and methods 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. Results 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. Conclusion 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.