Patterns of progression in non-IPF fibrotic interstitial lung disease

Purpose of review To characterize patterns of disease progression in the designation of progressive pulmonary fibrosis (PPF), including their relative prevalence and subsequent prognostic significance, in patients with fibrotic interstitial lung disease (ILD), including key patient sub-groups. Recent findings In recent large clinical cohorts, PPF criteria suited to early PPF identification, based on their prevalence and short time to progression, include a relative forced vital capacity (FVC) decline exceeding 10% and various combinations of lower thresholds for FVC decline, symptomatic worsening and serial progression of fibrosis on imaging. Amongst numerous candidate PPF criteria, these progression patterns may have the greatest prognostic significance based on subsequent mortality, although there are conflicting data based on subsequent FVC progression. The prevalence of patterns of progression is similar across major diagnostic sub-groups with the striking exception of patients with underlying inflammatory myopathy. Summary Based on prevalence and the prognostic significance of PPF criteria, and the need for early identification of disease progression, recent published data in large clinical cohorts provide support for the use of the INBUILD PPF criteria. The patterns of disease progression used to designate PPF in a recent multinational guideline are mostly not based on data in previous and subsequent real-world cohorts.