Patient-reported outcome (PRO) measures for clinical trials of COPD: the EXACT and E-RS

Abstract

The precise assessment of treatment efficacy in clinical trials requires scientific instruments that are not only relevant to the target population and treatment, but have been shown to be reliable, valid, and sensitive to change within the intended context of use. This paper describes the background, procedures, and current status of 2 patient-reported outcome (PRO) instruments developed for use in clinical trials of chronic obstructive pulmonary disease (COPD). The first measure, the EXAcerbations of Chronic pulmonary disease Tool (EXACT), was developed under the EXACT-PRO Initiative, a multi-year, multi-sponsor project involving experts in pulmonary medicine, instrument development, and drug development regulatory issues, dedicated to the development of a single, standardized instrument for evaluating the effects of treatment on acute exacerbations of COPD. The second measure, the EXACT-Respiratory Symptoms (E-RS) scale, is a derivative instrument comprising a subset of EXACT items to test the effect of treatment on the severity of respiratory symptoms in stable COPD. The EXACT-PRO Initiative was the first PRO instrument development consortia, and the EXACT and E-RS are the first PRO measures to undergo qualification review by the United States Food and Drug Administration (FDA).