Introduction: People with asthma-COPD overlap (ACO) have higher respiratory symptom burden, lower health status, and poorer pulmonary function than people with COPD alone. It is unclear whether people with ACO vs. COPD alone have greater abnormalities in cardiopulmonary exercise test (CPET) outcomes.

Aim: To compare detailed physiological responses at the symptom-limited peak of incremental CPET between people with ACO and COPD.

Methods: Participants included 411 ever smokers (63.5% male) with a FEV1/FVC <0.70 who completed CPET on a cycle ergometer at baseline of the CanCOLD study. ACO was defined using three clinical definitions: presence of atopy (n=103); physician diagnosed asthma (n=125); and combination of atopy and physician diagnosed asthma (n=65). People with COPD alone did not report atopy and/or physician diagnosed asthma (n=248).

Results: Compared to people with COPD, all ACO groups had lower respiratory-related health status, higher respiratory symptom burden, worse baseline pulmonary function, greater bronchodilator reversibility, and greater use of respiratory medications (all, p<0.05). Nevertheless, people with ACO (regardless of clinical definition) had similar physiological responses to CPET without evidence of greater pathophysiological abnormalities in peak exercise capacity (e.g., mean peak V?O2 of 78-82 vs. 80% predicted in ACO vs. COPD, respectively) compared to people with COPD alone (all, p>0.05).  

Conclusion: Above and beyond the established negative effect of COPD on CPET outcomes, the co-existence of asthma had no added detrimental effect.