Phenotypic heterogeneity in COPD and asthma

It has come as small comfort for pulmonary clinicians that the two most prevalent obstructive lung diseases, COPD and asthma, are being characterized as phenotypically heterogeneous.  While it sheds light on the challenging clinical management of patients with these diagnoses, it dredges up more concerns about how exactly this variability in presentation should and could be addressed to mitigate the disease-related impairment.

This month’s Clinical Review from Carolan and Sutherland [Journal of Allergy & Clinical Immunology 2013; 131(3): 627-634] compiles important advances in understanding COPD phenotypes, current knowledge of asthma phenotypes, where they overlap and the focus of therapies.  The authors cover guidelines, clinical phenotypes, exacerbations and morbidity in both diseases.  They also discuss radiologic phenotypes in COPD and the promising predictive tool, the BODE index, which applies BMI, obstruction, dypsnea, and exercise capacity to predict disease progression with greater accuracy than decline in FEV₁. 

Carolan and Sutherland note that COPD, unlike asthma, has not yet been sensitively correlated to any inflammatory biomarker, which has impaired programs for targeted drug development in COPD.  Phenotypic cluster analyses for both diseases are also covered in the authors’ review.  They comment that these efforts are creating alternative perspectives that may be useful for improving management of the variable clinical presentations.  Improved characterization of phenotype variability would permit development of personalized treatment regimens for both COPD and asthma.