The concept of control in chronic obstructive pulmonary disease: Development of the criteria and validation for use in clinical practice

Abstract

Guidelines of treatment of chronic obstructive pulmonary disease (COPD) identify symptom reduction and prevention of exacerbations as the main goals of therapy. Initial pharmacological treatment must be guided by these parameters, and effectiveness must be assessed at each clinical visit. However, there is no clear guidance as to how this assessment must be performed. The concept of control has been well developed in asthma, but it has been elusive in COPD. Patients with COPD may not be completely free from symptoms or exacerbations even under optimized therapy; therefore, control in COPD does not mean cure or absence of symptoms, but rather reaching the best clinical status possible according to the level of disease severity. A control tool has been developed based on a cross sectional evaluation of the impact of the disease and a longitudinal evaluation of stability. Low impact is a disease status defined by at least 3 of the following: low levels of dyspnoea, absence of or white sputum, low use of rescue medication and self-declared walking time of more than 30 minutes a day, and stability is the absence of moderate or severe exacerbations in the previous 3 months. Control can also be defined by COPD Assessment Test (CAT) scores ≤ 10 units for patients with FEV1 ≥ 50% and 16 for patients with FEV1 < 50% and stability as a change in CAT ≤ 2 units. Control of COPD is then defined as a status of low impact and stability. The control tool has been validated prospectively in several studies and has demonstrated to be sensitive to clinical changes and to have a good predictive value for poor outcomes. Clinical criteria are more reliable than CAT scores for the evaluation of control. The control tool is a quick and inexpensive method to evaluate clinical status and future risk of exacerbations that can be used at all levels of healthcare.