The Chronic Lung Disease Biomarker and Clinical Outcome Assessment Qualification Consortium (CBQC) evaluates the potential of biomarkers and outcome measures as drug development tools. Exercise endurance is an objective indicator of treatment benefit, closely related to daily physical function. Therefore, it is an ideal candidate for an outcome for drug development trials. Unfortunately, no exercise endurance measure is qualified by regulatory authorities for use in trials of chronic obstructive pulmonary disease (COPD) and no approved COPD therapies have claims of improving exercise endurance. Consequently, it has been challenging for developers to consider this outcome when designing clinical trials for new therapies. Endurance time during constant work rate cycle ergometry (CWRCE), performed on an electronically braked stationary cycle ergometer, provides an exercise endurance measure under standardized conditions. Baseline individualized work rate for each participant is set using an incremental test. During CWRCE the patient is encouraged to continue exercising for as long as possible. Although not required, physiological and sensory responses (e.g., pulmonary ventilation, heart rate, dyspnea ratings) are frequently collected to support interpretation of endurance time changes. Exercise tolerance limit is reached when the individual is limited by symptoms, unable to maintain pedaling cadence or unable to continue safely. At exercise cessation, exercise duration is recorded. An CWRCE endurance time increase from the pre-treatment baseline is proposed as a key efficacy endpoint in clinical trials. In COPD, improved exercise endurance has a direct relationship to the experience of physical functioning in daily life, which is a patient-centered, meaningful benefit.

Introduction

The COPD Biomarkers Qualification Consortium (CBQC) was formed under COPD Foundation management, with the goal of qualifying biomarkers and clinical outcome assessments through established regulatory processes for chronic obstructive pulmonary disease (COPD). Within CBQC, a working group evaluated opportunities for qualification of an exercise endurance measure. In a recent publication (Chronic Obstr Pulm Dis. 2022; 9[2]:252-265), we described a conceptual framework establishing exercise endurance's direct relationship to an individual with COPD's experience of physical functioning in daily life, and that increase in exercise endurance is a patient-centered, meaningful treatment benefit. We further proposed endurance time during constant work rate cycle ergometery (CWRCE) as a useful efficacy endpoint in clinical therapeutic intervention trials. In this current publication, we describe the process of assembling an integrated database of endurance time responses to interventions in COPD.

Methods

We sought participant-level data from published studies incorporating CWRCE as an outcome measure. A literature search screened 2993 publications and identified 553 studies for assessment. Two interventions had sufficient data across studies to warrant data extraction: bronchodilators and rehabilitative exercise training. Investigators were contacted and requested to provide participant-by-participant data from their published studies.

Results

The final dataset included data from 8 bronchodilator studies (2166) participants and 15 exercise training studies (3488 participants). The database includes 71 variables per participant, comprising demographic, pulmonary function, and detailed physiologic response data. This paper provides a detailed description of the analysis population, while analysis supporting the validation/qualification process and addressing other scientific questions will be described in subsequent publications.