Clinical and molecular markers in COPD

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous disease, and there is a clinical need for validated markers and biomarkers that can contribute to the assessment of patients, risk prediction, treatment guidance, and assessment of response. Although according to the 2018 GOLD guidelines clinically useful biomarkers for COPD patients in stable condition have yet to be identified, several clinical markers and biomarkers have been proposed for COPD. These include isolated clinical markers, such as symptoms and Health Status assessment, exercise tests, function tests and imaging, and also composite scores and molecular markers. However, and despite strong efforts to identify useful markers in an attempt to improve prognostic and therapeutic approaches, results have not been consistent and expectations of relying on these markers in near future are faint. Current approaches to COPD have shifted from treating the disease to treating the individual patient. There is a clear need to identify treatable traits, focusing more on the patient and not on the disease, in order to implement an increasingly personalized treatment of COPD in the clinic, leading to true precision medicine. There is a need to identify combinations of clinical markers and biomarkers, genetic markers, and phenotypes that can guide the personalized therapy of COPD patients. This critical review will therefore focus not only on currently established markers and biomarkers in COPD but also on possible future approaches toward precision medicine.