Abnormal breathlessness during cardiopulmonary exercise testing - validation in people with chronic airflow limitation

BackgroundExertional breathlessness is the cardinal symptom in cardiorespiratory disease. We aimed to validate recently developed normative reference equations to evaluate breathlessness abnormality during cardiopulmonary exercise testing (CPET) in people with chronic airflow limitation. MethodsAnalysis of people aged [≥]40 years with chronic airflow limitation undergoing CPET in the Canadian Cohort Obstructive Lung Disease (CanCOLD) study. Breathlessness intensity ratings (Borg 0-10 category ratio scale [CR10]) were evaluated in relation to power output (W), rate of oxygen uptake (VO2), and minute ventilation (VE) at peak exercise using normative reference equations as: 1) probability of breathlessness normality, defined as the predicted probability of the Borg CR10 rating among healthy references, with lower probability reflecting more severe breathlessness; and 2) presence of abnormal breathlessness, defined as a Borg CR10 intensity rating above the upper limit of normal (ULN). Validity of breathlessness severity (lower probability of normality) and abnormality (>ULN) was evaluated as correlations with relevant participant-reported and physiologic outcomes. ResultsWe included 330 participants (44% women): mean{+/-}SD age 64{+/-}10 years (range 40- 89), FEV1/FVC 57.3{+/-}8.2%, FEV1 75.6{+/-}17.9%predicted. Relative to peak W, VO2 and VE, abnormal breathlessness was present in 22.7%, 21.5%, and 15.2% of participants, respectively. For all equations, people with abnormal breathlessness had worse lung function, exercise capacity, self-reported symptom burden, physical activity, health-related quality of life, and physiological abnormalities during CPET. ConclusionEvaluation of breathlessness abnormality using CPET normative reference equations was valid in people with chronic airflow limitation.