COPD–asthma overlap heightens exacerbation risk

Oct 28 2013

Patients with chronic obstructive pulmonary disease (COPD) and concomitant asthma have significantly more exacerbations and hospitalizations than patients with COPD alone, research shows.

Ana Maria Menezes (Federal University of Pelotas, Brazil) and colleagues examined data from the Latin American Project for the Investigation of Obstructive Lung Disease (PLATINO) study. They found that out of 5044 participants who underwent pre- and post-bronchodilator spirometry, 12% had COPD alone, 1.7% had asthma alone, and 1.8% had COPD–asthma overlap.

Out of all affected patients, those in the overlap group had the highest percentage of cough and phlegm symptoms, the highest use of respiratory medication, were the most likely to have previously undergone spirometry, and to have had a physician diagnosis of asthma. Additionally, they had the lowest values for several lung function parameters, including pre- and post-bronchodilator forced expiratory volume in 1 second (FEV1), and FEV1 to forced vital capacity ratio.

The rate of exacerbations in the past year was lowest in the COPD-only group at 5.2%. Compared with these patients, those with COPD–asthma overlap were 2.1-fold more likely to have had at least one exacerbation in the past year, at a rate of 15.7%, after adjusting for confounders. Patients with asthma alone were also more likely to experience exacerbations than those with COPD, at 13.1%, but in multivariate analysis this did not reach statistical significance.

Additionally, patients in the overlap group were 4.1 times more likely to have been hospitalized in the past year than those with COPD (5.6 vs 1.2%), while there were no hospitalizations among asthma patients.

And, while a similar proportion of patients from each group experienced limitations due to their physical health, at around 30%, patients with COPD–asthma overlap were nearly 50% more likely to report their general health status as fair or poor compared with patients with COPD alone (53.9 vs 34.0%).

Writing in Chest, Menezes and colleagues say that their study “suggests that coexisting COPD–Asthma is possibly associated with increased disease severity, as well as worse health status.”

“However,” they add, “it remains unclear which are the pathogenic characteristics of this group, the stability of the phenotype over time, the best treatment and the long-term prognosis of these individuals.”

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