Idiopathic pulmonary fibrosis: lung function is a clinically meaningful endpoint for phase III trials.

Idiopathic pulmonary fibrosis causes progressive morbidity and has a worldwide incidence that is increasing. There are a number of promising therapies, one of which has been approved in Europe, parts of Asia, and India, and others that are at various stages of development. Despite this, there continues to be debate about the most appropriate clinical endpoint that should be used in future randomized controlled clinical trials of novel therapies in idiopathic pulmonary fibrosis. In a recent Pulmonary Perspective in this journal, the case for the use of a variety of clinical endpoints was analyzed, and the article concluded that FVC, the endpoint most commonly used recently and in ongoing studies, was not an appropriate option. In this Pulmonary Perspective we present a counterpoint in which we explore the basis on which this conclusion is drawn and present data that strongly and logically support the use of FVC as a valid and robust measure that fulfils the criteria for an ideal clinical endpoint and that is meaningful to patient and clinician alike.