Antifibrotic treatment response and prognostic predictors in patients with idiopathic pulmonary fibrosis and exposed to occupational dust

Our plain-English summary of Antifibrotic treatment response and prognostic predictors in patients with idiopathic pulmonary fibrosis and exposed to occupational dust, by V. Casillo, S. Cerri, A. Ciervo, et al (BMC Pulmonary Medicine, 2019).

The study

• Authors: V. Casillo, S. Cerri, A. Ciervo, M. Stendardo, L. Manzoli, M.E. Flacco, M. Manno, M. Bocchino, F. Luppi, P. Boschetto
• Journal: BMC Pulmonary Medicine
• Published: 2019;19(1):170
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Idiopathic Pulmonary Fibrosis (IPF) is an aggressive interstitial lung disease with an unpredictable course. Occupational dust exposure may contribute to IPF onset, but its impact on antifibrotic treatment and disease prognosis is still unknown. We evaluated clinical characteristics, respiratory function and prognostic predictors at diagnosis and at 12 month treatment of pirfenidone or nintedanib in IPF patients according to occupational dust exposure.

Methods: A total of 115 IPF patients were recruited. At diagnosis, we collected demographic, clinical characteristics, occupational history. Pulmonary function tests were performed and two prognostic indices [Gender, Age, Physiology (GAP) and Composite Physiologic Index (CPI)] calculated, both at diagnosis and after the 12 month treatment. The date of long-term oxygen therapy (LTOT) initiation was recorded during the entire follow-up (mean = 37.85, range 12-60 months).

Results: At baseline, patients exposed to occupational dust [≥ 10 years (n = 62)] showed a lower percentage of graduates (19.3% vs 54.7%; p = 0.04) and a higher percentage of asbestos exposure (46.8% vs 18.9%; p 0.002) than patients not exposed [< 10 years (n = 53)]. Both at diagnosis and after 12 months of antifibrotics, no significant differences for respiratory function and prognostic predictors were found. The multivariate analysis confirmed that occupational dust exposure did not affect neither FVC and DLCO after 12 month therapy nor the timing of LTOT initiation.

Conclusion: Occupational dust exposure lasting 10 years or more does not seem to influence the therapeutic effects of antifibrotics and the prognostic predictors in patients with IPF.

In plain English

This was an observational prospective cohort study of 115 consecutive patients newly diagnosed with idiopathic pulmonary fibrosis (IPF), a scarring lung disease, at hospitals in Modena and Naples, Italy, between 2014 and 2018. Patients were grouped by whether they had worked 10 or more years with dusts linked to IPF: 62 exposed and 53 not exposed. Reported asbestos exposure was more common in the dust-exposed group (46.8% vs 18.9%). There were 89 patients who took the antifibrotic drugs pirfenidone or nintedanib and were tested at diagnosis and after 12 months. In them, the two groups showed no significant differences in lung function or in two prognostic scores (GAP and CPI). Dust exposure was not linked to lung function after treatment, or to starting long-term oxygen therapy (hazard ratio 0.63, 95% CI 0.28 to 1.40). There were too few deaths (21) to analyse. The authors concluded that 10 or more years of occupational dust exposure does not seem to influence the effects of antifibrotics or the prognostic predictors. They noted that work histories were self-reported and the sample was small.

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: observational prospective cohort study
• Who was studied: 115 consecutive patients with a new diagnosis of idiopathic pulmonary fibrosis referred to the Center for rare lung disease of the University Hospital of Modena and the Pneumological clinic of the Federico II University Hospital of Napoli, Italy, January 2014 to December 2018. Of these, 89 were treated with pirfenidone or nintedanib and had lung function tests at diagnosis and after 12 months. Mean follow-up was 37.85 months (range 12 to 60).
• Exposure: Occupational exposure to dusts related to IPF (organic dusts; stone, sand or metal dusts; wood dust) lasting 10 or more years before diagnosis ('exposed', n = 62) versus less than 10 years ('not exposed', n = 53). Mean duration of dust exposure was 36.74 years in the exposed group and 1.2 years in the not exposed group. Asbestos exposure was also recorded. Of the asbestos-exposed patients in the dust-exposed group, 17 had occupational asbestos exposure and the others household or neighbourhood exposure. Only 3 patients in the not exposed group had occupational asbestos exposure.
• Main results:
  • At baseline, the dust-exposed group had a lower percentage of university graduates (19.3% vs 54.7%; p = 0.04) than the not exposed group. It also had a higher percentage reporting asbestos exposure (46.8% vs 18.9%; p 0.002).
  • Both at diagnosis and after 12 months of antifibrotic treatment, there were no significant differences in respiratory function or in the prognostic indices (GAP and CPI) between exposed and not exposed patients. This analysis was restricted to the 89 treated patients with complete tests.
  • In multivariate regression of the 89 treated patients, exposed vs not exposed was not significantly related to FVC % predicted at 1 year (coefficient 0.06, 95% CI -0.06 to 0.19, p 0.3). It was also not related to DLCO % predicted at 1 year (coefficient 1.17, 95% CI -3.01 to 5.17, p 0.6). Asbestos exposure was likewise not significantly related to FVC (coefficient -0.04, 95% CI -0.17 to 0.09, p 0.6) or to DLCO (coefficient -2.76, 95% CI -7.25 to 1.73, p 0.2).
  • During follow-up, 38 of the 115 patients (33%) started long-term oxygen therapy. Occupational dust exposure did not differ significantly between those who started it and those who did not (57.9% vs 52%). In the Cox model, being exposed vs not exposed was not a significant predictor of starting oxygen therapy (HR 0.63, 95% CI 0.28 to 1.40, p 0.3).
  • Higher baseline GAP score (HR 1.89, 95% CI 1.30 to 2.76) and CPI score (HR 1.07, 95% CI 1.02 to 1.12) predicted starting long-term oxygen therapy. Higher FEV1 lowered the risk (HR 0.38, 95% CI 0.17 to 0.85).
  • There were 21 deaths (18.2%), too few for a proper statistical analysis. Eleven deaths were from progression or exacerbation of IPF.
• The authors' conclusion: The authors concluded that occupational dust exposure lasting 10 years or more does not seem to influence the therapeutic effects of antifibrotics or the prognostic predictors in patients with IPF.
• Limitations the authors state:
  • Occupational history was self-reported, so recall bias is possible. Data on the intensity of dust exposure and on the time between the end of exposure and diagnosis were not available.
  • Complete lung function data at diagnosis and 12 months were available for only 89 patients, all treated. The authors stated there are no data to demonstrate that dust exposure does not affect the benefit of antifibrotic therapy at 1 year.
  • The sample was too small to evaluate each type of dust separately. It also gave too few deaths to perform a mortality analysis.
  • The GAP index has been validated at diagnosis, not at 1 year.

Topics

Medical terms in this study, explained in our Lexicon: Idiopathic, Pulmonary Fibrosis, Interstitial Lung Disease, Prognosis, Occupational History, Pulmonary Function Test (PFT), Supplemental Oxygen, Asbestos Exposure.

Related studies

• Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study — M.J. Abramson, T. Murambadoro, et al. (2020)
• The Role of Occupational and Environmental Exposures in the Pathogenesis of Idiopathic Pulmonary Fibrosis: A Narrative Literature Review — S.P. Trethewey, G.I. Walters (2018)
• Occupational exposures and idiopathic pulmonary fibrosis — G.I. Walters (2020)
• Exploring efficacy and safety of oral Pirfenidone for progressive, non-IPF lung fibrosis (RELIEF) - a randomized, double-blind, placebo-controlled, parallel group, multi-center, phase II trial — J. Behr, P. Neuser, et al. (2017)
• Smoking, occupational exposures, and idiopathic pulmonary fibrosis among Swedish construction workers — M. Andersson, P.D. Blanc, et al. (2021)
• Possible value of antifibrotic drugs in patients with progressive fibrosing non-IPF interstitial lung diseases — S.E. Torrisi, N. Kahn, et al. (2019)

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