Comprehensive characterisation of individuals with fibrotic interstitial lung disease: baseline insights from the INJUSTIS study

Our plain-English summary of Comprehensive characterisation of individuals with fibrotic interstitial lung disease: baseline insights from the INJUSTIS study, by F. Khan, I. Stewart, L. Howard, et al (BMJ Open Respiratory Research, 2026).

The study

• Authors: F. Khan, I. Stewart, L. Howard, C.M. Barber, R. Borton, R. Braybrooke, G. Hearson, S. Jones, T. Maher, L. Matthews, G. Saini, N. Thompson, A.M. Wilson, S.R. Johnson, G. Jenkins
• Journal: BMJ Open Respiratory Research
• Published: 2026;13(1)
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Interstitial lung disease (ILD) represents a group of complex parenchymal conditions characterised by varying clinical trajectories. The It's Not JUST Idiopathic Pulmonary Fibrosis Study seeks to identify genetic, proteomic and clinical biomarkers that distinguish rapidly progressive fibrotic phenotypes from stable phenotypes irrespective of aetiology. This manuscript presents baseline insights from the recruited cohort.

Methods: In this prospective, longitudinal study, participants with fibrotic ILDs, including idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis, rheumatoid arthritis-associated ILD, asbestosis and unclassifiable ILD, were enrolled from 24 UK sites. Participants underwent comprehensive baseline evaluation including demographics, exposure history, lung function testing, 6-min walk tests, blood sampling and standardised questionnaires to assess symptoms and quality of life.

Results: A total of 272 participants were recruited, predominantly older white males with a smoking history. Baseline lung function showed comparable forced vital capacity (mean 89.0% predicted), diffusion of carbon monoxide (mean 57.9% predicted) and 6-min walk distance (mean 302 m) across ILD subtypes. Hypertension was the most prevalent comorbidity, affecting 40.8% of participants, with no significant differences across subtypes. Anxiety and depression were notably lower in IPF than non-IPF (4.5%; 21.0%). Previous occupational exposure was reported in 68.8% of participants, with asbestos exposure the most prevalent (36%). Bird exposure was reported by 40.4% of participants, with no significant differences across subtypes. No significant differences in health-related quality of life scores were observed across subtypes.

Conclusions: Despite varied aetiologies, fibrotic ILDs exhibit demographic and functional similarities, including lung function and health-related quality of life suggesting commonalities in disease mechanisms.

Trial Registration Number: NCT03670576.

© Author(s) (or their employer(s)) 2026. Re-use permitted under CC BY. Published by BMJ Group.

In plain English

This paper reported baseline data from INJUSTIS, an ongoing prospective study at 24 UK sites that aims to find markers that tell worsening lung scarring apart from stable disease. Between November 2018 and May 2023 it recruited 272 people with fibrotic interstitial lung disease: idiopathic pulmonary fibrosis (67), asbestosis (54), fibrotic hypersensitivity pneumonitis (54), rheumatoid arthritis-related lung disease (47) and unclassifiable disease (50). Exposures were reported by the participants themselves. Asbestos exposure was reported by 36% of all participants, by every participant with asbestosis, and by 20.2% of those without asbestosis, with 9.2% of that group reporting significant exposure. Participants with asbestosis were older on average (75.9 years), 98.1% male, had the shortest six-minute walk distance (276 m), and had lower white cell and neutrophil counts than the other groups. Lung function was broadly comparable across groups. Bird exposure (40.4% overall) did not differ significantly between groups. The authors concluded the data offered insights into similarities and differences across subtypes. They noted the study was not large enough for detailed subtype comparisons and that self-reported exposure histories were open to recall bias.

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: Prospective, longitudinal multicentre cohort study. This paper is a descriptive analysis of baseline data only.
• Who was studied: 272 adults with fibrotic interstitial lung disease recruited at outpatient clinics at 24 UK sites between November 2018 and May 2023: IPF (n=67), asbestosis (n=54), fibrotic HP (n=54), RA-ILD (n=47) and uILD (n=50).
• Exposure: Self-reported occupational and environmental exposures, including asbestos (fiber type not specified), mineral dust, metal dust, welding fumes, wood dust and birds. 'Significant' asbestos exposure was defined as 1 year of heavy exposure or 5 to 10 years of moderate exposure.
• Main results:
  • Asbestos was the most commonly reported exposure: 36% of the whole cohort, 22.4% of the IPF group and 40.5% of the non-IPF group. All 54 participants with asbestosis reported it.
  • Among participants without asbestosis, 20.2% reported asbestos exposure, and 9.2% reported significant exposure.
  • Participants with asbestosis were older on average than the other subtypes (75.9 years, SD 6.3) and had the highest proportion of men (98.1%).
  • Six-minute walk distance was shortest in the asbestosis group (mean 276 m, SD 114 m), compared with 311 m in IPF and 299 m in non-IPF participants.
  • Baseline percent-predicted lung function was comparable between the IPF group (FVC 90.6, DLCO 58.3) and the non-IPF group (FVC 88.5, DLCO 57.7).
  • White cell and neutrophil counts were lower in the asbestosis group than in the other subtypes (p=0.02 and p=0.005).
  • The physical domain of the Leicester Cough Questionnaire differed across subtypes (p=0.04). It was lowest in asbestosis (median 5.1), where a lower score indicates more cough-related impact.
  • Hypertension was the most common other condition, affecting 40.8% of all participants.
  • Anxiety and depression were reported by 16.9% of participants: 4.5% of the IPF group and 21% of the non-IPF group.
  • Bird exposure did not differ significantly between ILD subtypes.
• The authors' conclusion: The authors concluded that this baseline evaluation offered insights into the similarities and differences across fibrotic ILD subtypes and provides a foundation for planned biomarker research.
• Limitations the authors state:
  • The cohort was mostly older white men with a smoking history, which may limit how far the findings apply to more diverse populations.
  • The sample size was designed to compare progressive with stable disease over follow-up, not to make detailed comparisons between ILD subtypes.
  • Recruitment delays during the COVID-19 pandemic may have caused survivor bias.
  • The extended recruitment period may have introduced bias over time, for example from changes in treatment practice.
  • Exposure histories and family histories were reported by the patients and are subject to recall bias.
  • The IPF group was generally milder than other cohorts.

Topics

Medical terms in this study, explained in our Lexicon: Interstitial Lung Disease, Idiopathic, Pulmonary Fibrosis, Biomarker, Pneumonitis, Exposure History, Quality of Life, Occupational Exposure.

Related studies

• The Its Not JUST Idiopathic pulmonary fibrosis Study (INJUSTIS): description of the protocol for a multicentre prospective observational cohort study identifying biomarkers of progressive fibrotic lung disease — F. Khan, I. Stewart, et al. (2019)
• Prognosis and causes of death of patients with acute exacerbation of fibrosing interstitial lung diseases — J. Salonen, M. Purokivi, et al. (2020)
• Differential diagnosis of usual interstitial pneumonia: when is it truly idiopathic? — W.A. Wuyts, A. Cavazza, et al. (2014)
• The evidence of benefits of exercise training in interstitial lung disease: a randomised controlled trial — L.M. Dowman, C.F. McDonald, et al. (2017)
• Causes of acute respiratory hospitalizations predict survival in fibrosing interstitial lung diseases — J. Salonen, H. Vähänikkilä, et al. (2020)
• Validation of the Brazilian Portuguese version of the University of California San Diego Shortness of Breath Questionnaire in patients with interstitial lung disease — H. Silva, L.C. Mantoani, et al. (2021)

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