Lung Function Course of Patients With Pulmonary Fibrosis After Initiation of Anti-Fibrotic Treatment: Real-World Data From the Dutch National Registry

Abstract

Background and objective: Real-world data on lung function course of patients with progressive pulmonary fibrosis (PPF) treated with anti-fibrotic medication are limited. We evaluated forced vital capacity (FVC) decline in patients with PPF and idiopathic pulmonary fibrosis (IPF) who started anti-fibrotic treatment.

Methods: This was a nationwide multi-centre registry study in 16 hospitals throughout the Netherlands. Patients treated with anti-fibrotic medication, with at least two in-hospital pulmonary function tests before and after the initiation of anti-fibrotic treatment, were included. Linear mixed-effects modelling was used to analyse lung function trajectories 1 year before and after the start of anti-fibrotic treatment.

Results: Data from 538 patients (n = 142 with PPF, n = 396 with IPF) were analysed. In PPF, the mean annualised FVC decline was 412 mL (95% confidence interval [CI]: 308-517 mL) before the initiation of anti-fibrotic treatment, and 18 mL (95% CI: 9-124 mL) in the first year after. The corresponding declines for IPF were 158 mL (95% CI: 78-239 mL) and 38 mL (95% CI: 24-101 mL). In both groups, treatment significantly slowed down FVC decline, although the change was larger in the PPF group (p = 0.0006). In the first year after treatment initiation, 23.9% of patients with PPF and 28.0% with IPF had disease progression.

Conclusion: The FVC decline significantly slowed after the initiation of treatment for both IPF and PPF. Nevertheless, a significant proportion of patients exhibited disease progression, despite the start of anti-fibrotic treatment. Early identification of these patients is crucial for treatment adaptations and inclusion in clinical trials.

Keywords: anti‐fibrotic medication; idiopathic pulmonary fibrosis; lung function; progressive pulmonary fibrosis.

FIGURE 1

Estimated average lung function trajectories, with corresponding 95% confidence intervals, in idiopathic and progressive pulmonary fibrosis before and after anti‐fibrotic treatment initiation. DLCO, diffusing capacity of the lung for carbon monoxide; FVC, forced vital capacity; IPF, idiopathic pulmonary fibrosis; PPF, progressive pulmonary fibrosis. Linear mixed‐effects model analysis of in‐hospital forced vital capacity (FVC) in both litres and percent predicted, and diffusion capacity of the lungs for carbon (DLCO) in percentage predicted from 1 year before and after treatment initiation. Black represents the patients diagnosed with idiopathic pulmonary fibrosis, and red demonstrates the patients with progressive pulmonary fibrosis. Annual changes in FVC, FVC percentage predicted, and DLCO percentage predicted are displayed before and during anti‐fibrotic treatment in the left, middle, and right panels, respectively. The dotted lines represent the anticipated disease course, without initiation of anti‐fibrotic treatment.