Prevalence of progressive fibrosing interstitial lung disease

Background: There is an important group of patients with a progressive fibrosing form of interstitial lung disease (PF-ILD) (Flaherty, K.R. et al. BMJ Open Respir Res 2017;4:e000212) who do not meet idiopathic pulmonary fibrosis (IPF) diagnostic criteria but have a similar natural history and prognosis. Compared to IPF, the relative prevalence of PF-ILD is unknown. Aims and objectives: To estimate the prevalence of PF-ILD in Europe and the USA. Methods: Systematic literature review in Medline and Embase (1990–2017) focused on the prevalence of ILD and the forms of ILD known to be at risk for a progressive fibrosing phenotype. Supplemented by data from physician surveys and interviews, prevalence estimates were generated for each subtype and then combined to estimate overall PF-ILD prevalence. Sensitivity analyses were performed to determine the upper bounds of the estimate. Results: The overall prevalence of ILD (per 10,000 persons) was reported as 0.63–7.6 in 4 studies in Europe and 7.43 in the USA. Prevalence estimates for individual progressive fibrosing ILDs and PF-ILD overall are presented in the Table. PF-ILD prevalence (per 10,000 persons) ranged from 0.22–2.0 in Europe and was 2.80 in the USA. Conclusions: PF-ILD affects fewer than 5 in 10,000 persons in Europe and the USA, a patient population with an unmet need for treatment. Funding: Boehringer Ingelheim. Editorial assistance: Complete HealthVizion.