Asthma COPD overlap versus COPD alone in Australian primary care

Introduction: Many older adults with a history of smoking and asthma develop clinical features of both asthma and COPD, an entity now named Asthma-COPD Overlap (ACO) syndrome. People with ACO are at higher risk of poor health outcomes than patients with asthma or COPD alone. However understanding of ACO is limited, and more information is needed about its clinical and physiological characteristics to better inform patient management. Aim: We aimed to compare the demographic characteristics, self-reported dyspnoea, quality of life and lung function between ACO and COPD, in adult long-term smokers or former smokers (≥10 pack years) from Australian general practices participating in a trial of an interdisciplinary community-based model of care.Methods: We used data from the RADICALS (Review of Airway Dysfunction and Interdisciplinary Community-based care of Adult Long-term Smokers) trial. Baseline characteristics, pre- and post-bronchodilator spirometry, dyspnoea scores and St. George's Respiratory Questionnaire scores were compared between 60 ACO patients and 212 with COPD alone. ACO was defined by bronchodilator reversibility.Results: Pre-bronchodilator values of FEV1 (mean±SD 58.4 ± 14.3 vs 67.5 ± 20.1 %predicted) and FVC (mean 82.1 ± 16.9 vs 91.9 ± 17.2 %predicted) were significantly lower in the ACO group (P < 0.001), but no difference was found in post-bronchodilator spirometry. Demographic and clinical characteristics, dyspnoea, quality of life, comorbidities and treatment prescribed did not differ significantly between groups.Conclusion: This study has described ACO in Australian general practices. Our finding of lower pre-bronchodilator lung function in ACO patients compared to COPD, provides further reinforcement to the importance of spirometry in primary care to inform the selection of pharmacotherapy/ management.