Physiologic and biological markers to assess the progression of chronic obstructive pulmonary disease [Quali parametri funzionali e biologici per la valutazione della progressione della broncopneumopatia cronica ostruttiva]

Chronic obstructive pulmonary disease (COPD) is a multi-component disease characterised by a range of pathological changes, which include mucus hypersecretion, airway narrowing and loss of alveoli in the lungs, and loss of lean body mass and cardiovascular effects at a systemic level. COPD patients are also heterogeneous in terms of clinical presentation, disease severity and rate of disease progression. Their degree of airflow limitation, as measured by FEV1, is known to be poorly correlated to severity of symptoms, which adds to the difficulties of researchers who are trying to improve the definition of COPD and current disease staging systems. Since the relationship between spirometry and symptoms appears to be poor, measures of lung physiology may not adequately describe alone both the social impact of COPD and the effectiveness of therapeutic interventions in individual patients. Most researchers regard patient-centred outcomes such as symptoms, exacerbations, exercise capacity and health-related quality of life as important as changes in lung function. At this time, no surrogate marker of COPD or its exacerbations has been identified other than FEV1, but the value of FEV1 as a surrogate marker is limited. Mortality dyspnea and health-related quality of life remain the most important clinical outcomes in COPD research. Other potential surrogate markers should be included as secondary endpoints in future clinical trials. This may lead to the identification of biomarkers that correlate with patient-centred outcomes. Generation of such data may also help in the development of new hypotheses for future clinical trials.