Family members with pulmonary fibrosis showed correlations for predicted forced vital capacity trajectories and computed tomography patterns, based on data from 101 individuals in 45 families.
Patients with familial pulmonary fibrosis (FPF), defined as fibrotic interstitial lung disease among two or more first-degree or second-degree relatives, have worse survival than that of patients with sporadic pulmonary fibrosis, wrote Tinne Goos, MD, of KU Leuven, Belgium, and colleagues. Diagnosis of FPF diagnosis is mainly based on family history, and data on intrafamilial correlations are lacking, they said.
In a study published in the journal Chest, the researchers identified FPF patients treated at a single center. The study population included 101 patients from 45 families; most of these (34) were siblings. Overall, 61.4% of the participants were men, 69.3% were ever-smokers, and 84.2% had idiopathic pulmonary fibrosis.
The analysis included data on computed tomography (CT) scanning and predicted forced vital capacity (FVC%), as well as age at diagnosis, treatment type, gender, smoking history, and date of diagnosis.
Overall, FVC%predicted was significantly correlated within families, with a correlation of 0.75. The annual change in FVC was –158.2 mL, and the annual change in FVC%predicted was –6.3%.
Sixty-five patients received antifibrotic treatment, and 18 received immunosuppressive treatment. Immunosuppressive treatment remained significantly correlated among families in a multivariate analysis, with a correlation of 0.77.
“Age at diagnosis correlated within a generation, while patients from a second generation were diagnosed younger,” the researchers noted. The current study findings and results from other studies suggest a genetic basis for FPF age of onset, and determining an age range for screening unaffected relatives based on the age at diagnosis of affected relatives might be useful, they said.
In addition, 42.2% of families showed concordance of CT scan patterns. Typical usual interstitial pneumonia (UIP) appeared in 35 patients, atypical UIP in 36 patients, UIP with emphysema in 9 patients, and findings incompatible with UIP in 21 patients.
The study findings were limited by several factors including the retrospective design and use of data from a single center, as well as by the changes in clinical practice guidelines between 2004 and 2019, with increases in genetic testing, the researchers noted.
However, the current study is the first known to report on FVC evolution within families in FPF, they said. Future studies of both intra- and interfamilial correlation and variability are needed to identify the genetic and environmental factors that may affect disease manifestation and progression, they concluded.
The study was supported by Research Foundation-Flanders. Dr. Goos had no financial conflicts to disclose.