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Am J Respir Crit Care Med. 2012 May 15;185(10):1044-8. doi: 10.1164/rccm.201201-0006PP. Epub 2012 Apr 13.

Idiopathic pulmonary fibrosis: clinically meaningful primary endpoints in phase 3 clinical trials.

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Division of Pulmonary and Critical Care Medicine, Campus Box 356175, University of Washington, Seattle, WA 98195, USA.


Definitive evidence of clinical efficacy in a Phase 3 trial is best shown by a beneficial impact on a clinically meaningful endpoint-that is, an endpoint that directly measures how a patient feels (symptoms), functions (the ability to perform activities in daily life), or survives. In idiopathic pulmonary fibrosis (IPF), we believe the endpoints that best meet these criteria are all-cause mortality and all-cause nonelective hospitalization. There are no validated measures of symptoms or broader constructs such as health status or functional status in IPF. A surrogate endpoint is defined as an indirect measure that is intended to substitute for a clinically meaningful endpoint. Surrogate endpoints can be appropriate outcome measures if validated. However, validation requires substantial evidence that the effect of an intervention on a clinically meaningful endpoint is reliably predicted by the effect of an intervention on the surrogate endpoint. For patients with IPF, there are currently no validated surrogate endpoints.

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