ERS technical standard on reference values for cardiopulmonary exercise testing: summary report and a call for action

Abstract

Background Cardiopulmonary exercise testing (CPET) assesses physiological responses to incremental exercise and identifies potential causes of exercise limitation. There have been several population-specific reference equations published, but none that span the human age range. It would be advantageous to have all-age global reference ranges. This task force aimed to derive Global Lung Function Initiative reference equations for peak oxygen uptake (VO2peak) and peak work rate (Wpeak) in healthy individuals. Methods CPET data were collected retrospectively. Generalised additive models of location, shape and scale were used to develop reference ranges, including age, sex, height and weight as explanatory variables. The influence of geographic region, equipment, testing protocols and averaging methods for peak exercise data were also examined. Results Data from 5956 healthy individuals aged between 6 and 83 years across 17 sites in Europe, North and South America and Asia were analysed. There was substantial between-subject variability in both VO2peak and Wpeak, with wide confidence intervals across age groups. Heterogeneity in VO2peak was related to geographic region, metabolic cart type, and averaging methods for peak exercise values. Controlling for these variables improved model fit, but not sufficiently to be reliable predictors for reference ranges. Conclusion Significant heterogeneity in CPET testing methodology and outcomes between sites precluded the development of reference ranges for VO2peak and Wpeak. This task force has developed a framework for prospective data collection with strictly standardised protocols and centralised data analysis to reduce variability and establish robust, clinically meaningful reference ranges for CPET outcomes.