More attention should be given to patients who have chronic obstructive pulmonary disease (COPD) and concomitant asthma, after a study showed that nearly one-fifth of patients with COPD fall into this subtype.
Patients with overlap of the two conditions experienced poorer symptom control, had lower quality of life (QoL), and took part in less physical activity compared with other patients with COPD, despite having similar forced expiratory volume in 1 second (FEV1) values and less exposure to smoking.
"Clear diagnostic criteria and management guidelines for this phenotype must be developed and prospectively validated, and this phenotype should be incorporated in phenotype-guided management of COPD," say authors Marc Miravitlles (Vall d'Hebron University Hospital, Barcelona, Spain) and colleagues.
The study included data on 3885 participants aged 40-80 years who were part of the population-based EPI-SCAN study. Overall, 385 participants had COPD, defined as a post-bronchodilator FEV1/forced vital capacity ratio of less than 0.7, of whom 67 (17.4%) had also been diagnosed with asthma.
The authors found that patients with overlap COPD-asthma were more likely to be women (55.2 vs 24.2%), to never have smoked (56.7 vs 19.5%), and have a significantly higher body mass index (29.1 vs 27.8 kg/m2) than non-overlap patients. However, spirometry and 6-minute walking test results were similar between the two groups.
Additionally, overlap patients had a higher Charlson comorbidity index than non-overlap patients, and were more likely to have dyspnea (67.2 vs 16.0%) and wheezing (92.5 vs 58.2%). Overlap patients also had significantly more exacerbations than non-overlap patients (average of 1.8 vs 0.5/year), had significantly impaired respiratory-related QoL, and took part in less physical activity.
Writing in Respiratory Medicine, the authors explain that COPD-asthma overlap has not been well characterized and that controversy over the definition of the phenotype remains. However, they note that previous research has indicated that patients with coexisting COPD and asthma may have a higher risk for death than those with either condition alone.
"These results indicate the importance of proper diagnosis and management of this particular subset of mixed-disease patients," the authors conclude.
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