The effect of pirfenidone on disease progression in asbestosis patients: a real-world Dutch cohort study

Our plain-English summary of The effect of pirfenidone on disease progression in asbestosis patients: a real-world Dutch cohort study, by I. Smesseim, A.E. Wind, J.R. Miedema, et al (ERJ Open Research, 2025).

The study

• Authors: I. Smesseim, A.E. Wind, J.R. Miedema, B. Boerrigter, I.A. Wiertz, V. van der Noort, J.C. Grutters, J.A. Burgers
• Journal: ERJ Open Research
• Published: 2025;11(6)
• Type of article: Letter
• Read it: PubMed · Publisher · Free full text

Abstract

Findings based on asbestosis patients treated between 2004 and 2024 reveal a modest reduction in the rate of FVC decline (mean (95% CI) difference 7.0 (-5.8-19.7) mL·month-1, p=0.22) and D LCO decline (0.11% (-0.19-0.41%), p=0.30) after starting pirfenidone https://bit.ly/45fZ5TR.

Copyright ©The authors 2025.

In plain English

This research letter reported a retrospective study at four hospitals in the Netherlands. It looked at adults with asbestosis who took pirfenidone, an antifibrotic drug, for at least 12 weeks between January 2014 and January 2024. Patients were drawn from a national database of people applying for compensation for asbestos-related disease. Of 479 applicants who met the asbestosis criteria, 22 were included. Their median age was 73.5 years and 90.9% were male. The authors compared how fast lung function fell before and after starting the drug. Average decline in forced vital capacity (FVC) went from 26 mL per month before pirfenidone to 19 mL per month on it. That is a difference of 7.0 mL per month (95% CI −5.8 to 19.7, p=0.22), which was not statistically significant. Decline in DLCO, a measure of gas transfer in the lungs, slowed by 0.11 percentage points per month (95% CI −0.19 to 0.41, p=0.30). Seven patients needed dose reductions for side effects. Citing the small sample and retrospective design, the authors concluded that their results did not show a significant reduction in decline, and they called for further research.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Multicentre retrospective cohort study (research letter) comparing lung function decline before and after starting pirfenidone
• Who was studied: 22 adults with asbestosis treated with pirfenidone for over 12 weeks at four Dutch hospitals, January 2014 to January 2024. They were selected from 479 people in a national compensation database who met asbestosis criteria. Median age was 73.5 years, 90.9% were male and 90.9% were former smokers. Only one had histology-proven asbestosis.
• Exposure: Treatment with pirfenidone at a target dose of 801 mg three times daily. Asbestosis diagnosis required at least five fibre-years of asbestos exposure, 15 or more years before symptom onset. Fiber types were not specified.
• Main results:
  • In the 22 patients, the rate of FVC decline was 7.0 mL per month smaller after pirfenidone (95% CI −5.8 to 19.7, p=0.22). It went from an average decrease of 26 mL per month before treatment to 19 mL per month on treatment.
  • The rate of DLCO decline was 0.11 percentage points per month smaller after pirfenidone (95% CI −0.19 to 0.41, p=0.30). It went from an average decrease of 0.48 points per month before treatment to 0.37 points per month after.
  • Seven of 22 patients (31.8%) had clinically significant drug-related adverse effects, including decreased appetite and diarrhoea, that required dose reduction.
  • Two patients (9.1%) stopped treatment because of intolerable toxicity. Fifteen (68.2%) stopped because of clinical deterioration. Five (22.7%) remained on treatment until death.
• The authors' conclusion: The authors concluded that, in this small cohort, their results did not show a significant reduction in FVC or DLCO decline in treated patients. They said this highlights the need for further research.
• Limitations the authors state:
  • The sample was small, partly because asbestosis is rare and off-label pirfenidone use is limited. It remains uncertain whether a significant effect could have been detected.
  • The retrospective design may have introduced selection or information bias.
  • Lung function tests were not done at fixed intervals and were done at various hospitals, introducing the risk of measurement variability.
  • Because of the retrospective design, self-reported adverse events were not reliably reported.

Topics

Medical terms in this study, explained in our Lexicon: Disease Progression, Cohort Study.

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