ABSTRACT
The past two decades have seen a proliferation of clinical trials whose primary objective has been to provide evidence of effectiveness and help place drugs within national and international treatment guidelines. Increasingly, evidence is being sought to provide proof of the anti-inflammatory action of drugs and improve understanding of how drugs work. Asthma and chronic obstructive pulmonary disease (COPD) are both chronic inflammatory diseases of the airways in which inflammation is a prominent feature and is broadly associated with clinical disease. In both conditions, it is difficult to assess the nature or degree of airway inflammation from clinical parameters alone. Direct indices of airway inflammation can correlate with clinical parameters such as symptoms, degree and variability of airflow limitation, and airway responsiveness that are normally monitored during a clinical trial. However, the correlation is not good for all parameters, and changes in various inflammatory and clinical parameters of disease activity may not occur simultaneously.
