Treatment of overlapping asthma and COPD –can guidelines contribute in an evidence-free zone?

Asthma and chronic obstructive pulmonary disease (COPD) are often clearly distinguishable diseases. There are, however, many people who demonstrate features of both. This is often termed the asthma-COPD overlap syndrome (ACOS); it is clinically important since these patients have worse health outcomes than those with either disease alone do, and some existing guidelines for treatment of either disease conflict. ACOS patients have also been specifically excluded from major clinical trials related to either condition. There is thus at this time little evidence on how to treat them, many of whom present in primary care settings. Reddel highlights the urgent need for research in this area and summarizes the interim recommendations provided in a collaborative report by Global Initiative for Asthma (GINA) and Global Initiative for chronic Obstructive Lung Disease (GOLD) (J Allergy Clin Immunol 2015; 136(3): 546-552).

Patients with ACOS present widely varying clinical histories, from adult cigarette smokers with childhood-onset asthma to lifelong non-smokers with fixed airflow limitation to emphysema patients who also have allergic disease. ACOS cannot be thought of as a single disease or phenotype, yet primary care settings rarely permit in-depth diagnostic consultations, and forming clinical guidelines is challenging in the absence of relevant data from similar patient populations.

Some countries have recognized the overlap in recently published national asthma guidelines and COPD guidelines, but often only with the concept of two separate, coexisting diseases. The joint GINA/GOLD interim ACOS recommendations, first published in 2014, recognize that asthma and COPD form part of a spectrum of overlapping phenotypes of airways disease. They suggest targeting treatment on the basis of predictors of risk, which is useful given the lack of evidence for treatment efficacy or effectiveness for the ACOS-affected population, and they outline five pragmatic steps to diagnose and initially treat ACOS.

Interest in and recognition of the importance of overlapping asthma and COPD is rapidly escalating. It is urgently necessary to study broad populations with chronic respiratory disease in order to develop a precise definition for ACOS, characterize its phenotypes, and identify opportunities for targeted treatment.