Algorithm incorporating cardiopulmonary exercise testing to identify symptoms and disability in COPD: Proof of concept

Abstract

Identifying individuals with symptoms or disability informs optimal chronic obstructive pulmonary disease (COPD) management. We evaluated an algorithm incorporating questionnaires (modified Medical Research Council [mMRC] and COPD Assessment Test [CAT]) and standardized incremental cardiopulmonary exercise testing (CPET) to identify people with symptoms/disability in COPD. Analysis of 304 people (36% women) with spirometry-defined COPD aged 42–89 years in the Canadian Cohort Obstructive Lung Disease study. The 3-step algorithm categorized people as having symptoms/disability if meeting any of: step 1) CAT-total≥10, mMRC≥2 or CAT breathlessness [CAT-B] item≥3; and/or step 2) abnormally high exertional breathlessness intensity (>upper limit of normal by peak exercise); and/or step 3) abnormally low exercise capacity (peak power output<lower limit of normal). Reclassification and associations with physiological impairments, future risk of moderate/severe exacerbations and all-cause mortality were evaluated. A CAT-B≥3 could replace mMRC≥2 with high accuracy (80%) and similar performance in the algorithm. Step 1 classified 64% as asymptomatic , of whom 13% and 27% were reclassified as having symptoms/disability by having abnormally high breathlessness (step 2), or abnormally low exercise capacity (step 3), respectively. People categorized by the algorithm as having symptoms/disability versus not had worse physiological impairments, increased risks of moderate/severe exacerbations ([hazard ratio] 2.60; [95% confidence interval] 1.96–3.47), and tended to have increased all-cause mortality (2.06; 0.93–4.59). In COPD, a stepwise algorithm using CAT and standardized CPET improves identification of adults with symptoms or disability with worse health outcomes and more treatable traits.