Gender differences in clinical features, comorbidities and prognostic outcomes in idiopathic pulmonary fibrosis—a retrospective cohort analysis from the British Thoracic Society Interstitial Lung Disease Registry

Background Idiopathic pulmonary fibrosis (IPF), an unknown aetiology type of interstitial lung disease (ILD), carries the poorest prognosis and is more common in males and the elderly. Gender differences in baseline presentation, lung function and comorbidities may have an impact on prognostic outcomes. Objective The aim of this study was to explore gender differences in clinical features, comorbidities and outcomes in IPF in a UK cohort. Method This was a retrospective cohort study analysing data from the British Thoracic Society UK IPF ILD Registry from January 2013 to February 2024. We compared baseline characteristics between males and females, and a survival analysis in both genders was performed using the Cox proportional hazards model. Results We identified 6666 IPF patients with a mean age at diagnosis of 74.1±8.1. Our cohort was predominantly male (5197, 78%), with a higher proportion of current and ex-smokers compared with females (69.9% vs 59.9%, p<0.001) and higher rates of comorbidities such as ischaemic heart disease (IHD) and diabetes (19.7% vs 14.6% and 19.9% vs 11.2%, respectively, p<0.001). Baseline forced vital capacity (FVC) % predicted was 77.76±17.4 in males and 81.83±19.7 in females (p=0.001), while diffusing capacity for carbon monoxide (DLCO) was similar between the two groups. In multivariate analysis, after adjusting for age, IHD and lower baseline FVC, DLCO was a poor survival predictor in males. Hiatus hernia is a protective factor. Conversely, disease duration of <12 months, gastro-oesophageal reflux disease, not requiring oxygen at baseline and higher baseline DLCO predicted better survival in females. Conclusion Gender differences in baseline characteristics and prognostic factors were observed in IPF. A gender-based approach in managing IPF is warranted, and further studies are needed to clarify these differences and their impact on IPF management.