Clinically important deterioration: a composite tool for managing patients with COPD.

Clinically important deterioration (CID) is a composite tool developed to measure COPD's progression. It is a promising concept that can improve treatment choices for COPD patients because it provides a more holistic assessment of their status in everyday clinical practice. The post hoc analysis of several trials that were important for improving COPD treatment provides increasing evidence of the importance of assessing CID. These retrospective evaluations suggest that dual bronchodilation should be preferred over a single bronchodilator if treatment aims to reduce a possible clinical deterioration of COPD. Should dual bronchodilation prove ineffective, evidence shows that triple therapy, including an inhaled corticosteroid, is effective in preventing CID, especially in the presence of high blood eosinophil counts. CID initially included changes in FEV1 ≥100 mL from baseline, an increase in total SGRQ score ≥4 units, or a moderate/severe exacerbation. These thresholds were chosen arbitrarily because they were considered clinically relevant. Therefore, this multidimensional tool is being improved by including outcomes and thresholds that consider the peculiarities of the COPD population and the duration of the assessment. However, at present, studies that have assessed the impact of CID on COPD are almost all retrospective. Therefore, prospective studies need to be conducted that allow the complete validation of this instrument and better define the most effective components in assessing the risk of deterioration of COPD.