Biomarkers that predict and guide therapy for exacerbations of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease. COPD exacerbations have a major impact on morbidity and mortality. The etiology of COPD exacerbations is largely due to viral and bacterial infections in combination with underlying inflammation that is typically neutrophilic, although it is eosinophilic in 10 to 25% of cases. We review the recent studies that have defined novel biological clusters at exacerbation events and consequently identified important biomarkers to direct therapy. These biomarkers include C-reactive protein, procalcitonin, and peripheral blood eosinophil count, which are readily available. We are therefore at a point of making personalized antibiotic and corticosteroid therapy in COPD exacerbations a reality. Integration of the wealth of emerging data to further define the complexity of exacerbations also promises to identify new targets and biomarkers to treat COPD exacerbations.