The multicentre study was conducted within the European chILD-EU network, with contributions from the DZL sites BREATH, CPC-M and UGMLC. DZL researchers Professor Matthias Griese from CPC-M and PD Dr Nicolaus Schwerk from BREATH played a leading role in the publication as first and senior authors, respectively. The registry includes children and adolescents from 23 countries and comprises more than 1,000 cases collected over a period of up to 20 years. For every patient entered into the registry, the diagnosis is reviewed by a panel of experts according to standardised criteria, using CT images and, where available, tissue samples. This systematic approach is important because the term “fibrosis” has not always been used consistently in clinical practice.

Significantly poorer lung function

“The results of the study show more clearly than expected that pulmonary fibrosis in chILD is not a marginal phenomenon. Depending on the definition applied, approximately one in five children shows corresponding changes; even when stricter criteria are used, the figure is still around one in nine,” says PD Dr Nicolaus Schwerk, summarising the findings. The paediatrician specialises in interstitial lung diseases in his outpatient clinic at the Department of Paediatric Pneumology, Allergology and Neonatology at Hannover Medical School. The findings demonstrate that fibrotic remodelling processes play a greater role in childhood than previously assumed.

Even more important, however, is what this fibrosis means for the subsequent course of the disease. Children with fibrotic changes consistently have poorer outcomes. Their lung function, measured by forced vital capacity, remains approximately 15 to 20 per cent lower than that of children without fibrosis. This is not a short-term effect, but one that remains stable over several years.

Higher risk of death or lung transplantation

Differences are also evident in survival. Children with fibrosis have a significantly higher risk of dying during the course of the disease or requiring a lung transplant. This association remains even after factors such as age, sex and body weight are taken into account. Notably, a higher body mass index was associated with a more favourable prognosis, a finding similar to observations made in other chronic lung diseases.

The results point in the same direction regardless of whether the broader registry definition or the stricter criteria used in clinical trials are applied. This suggests that the observed effect is robust and does not depend on a particular definition.

What do the findings mean for clinical practice?

The study findings have several implications for clinical practice. First, they demonstrate the importance of specifically and systematically documenting fibrotic changes in children with chILD. Second, these changes provide valuable prognostic information, as they identify patients who are likely to experience a less favourable course of disease. Third, the findings bring the question of treatment into sharper focus.

One antifibrotic medication is approved for children aged six years and older. Other antifibrotic treatments are currently used only in adults, but may also have potential for affected children in the future and should urgently be investigated in paediatric clinical trials.

The study provides three clear messages:

• Detect fibrosis early: Standardised criteria help to identify affected children reliably.
• Improve the assessment of disease progression: Fibrosis is an important marker of poorer lung function and a less favourable prognosis.
• Rethink treatment: Children with fibrosis may benefit from antifibrotic therapies, an approach that has already been successfully established in adults.

Original publication: Griese M, Reu-Hofer S, Ley-Zaporozhan J et al. chILD-EU collaborators; Schwerk N, Seidl E. Prevalence and disease trajectories of pulmonary fibrosis of childhood interstitial lung disease: a register-based, multicentre observational study. Lancet Respir Med. 2026 Jun 24:S2213-2600(26)00052-4. doi: 10.1016/S2213-2600(26)00052-4. Epub ahead of print. PMID: 42341791.