Digital clubbing predicts the efficacy of antifibrotic drugs in patients with idiopathic pulmonary fibrosis.

Abstract

Background: The introduction of antifibrotic drugs elicited a significant paradigm shift in the treatment of fibrosing interstitial lung diseases such as idiopathic pulmonary fibrosis (IPF). However, it remains unclear which clinical characteristics of IPF patients predicts therapeutic efficacy, and there has been limited investigation of the relationship between physical findings. The aim of this study was to investigate whether various clinical factors, including physical findings at the initiation of antifibrotic therapy, had an impact on the clinical response to treatment.

Methods: We retrospectively examined baseline clinical characteristics of IPF patients to identify features associated with better responses to antifibrotic drugs. We identified 257 consecutive patients with progressive pulmonary fibrosis who received antifibrotic therapy between March 2009 and May 2021, including 153 patients treated with pirfenidone and 104 patients treated with nintedanib. Of these, 66 patients with IPF had comprehensive baseline data recorded at the time of therapy initiation, including gender, age, smoking history, symptoms, physical findings including digital clubbing, biomarkers, and pulmonary function. Based on pulmonary function at 6 months after initiation of treatment, these patients were classified into a non-deterioration group and a deterioration group. Baseline data at the initiation of antifibrotic therapy were compared between these two groups.

Results: Twenty-two patients were classified into the deterioration group and 44 into the non-deterioration group. The annualized change in forced vital capacity (FVC) was -385.8±363.3 mL in the deterioration group and 94.1±207.0 mL in the non-deterioration group. The only significant difference in baseline characteristics between the groups was the presence of digital clubbing, observed in 5 of 22 patients (22.7%) in the deterioration group and in 22 of 44 patients (50.0%) in the non-deterioration group (P=0.04). Our findings indicate that IPF patients with digital clubbing experienced a smaller annual decline in FVC following antifibrotic therapy compared to those without digital clubbing.

Conclusions: These findings suggest that the presence or absence of digital clubbing in IPF patients may predict the annual rate of FVC decline following antifibrotic therapy. Antifibrotic drugs may be more effective in IPF patients who present with digital clubbing.