A Systematic Review and Meta-Analysis of Sputum Purulence to Predict Bacterial Infection in COPD Exacerbations

The 2020 Global Initiative for Obstructive Lung Disease (GOLD) Report highlights the importance of sputum purulence in the decision to prescribe antibiotics for acute exacerbations. The purpose of this systematic review and meta-analysis was to evaluate the strength of literature supporting inclusion of sputum purulence in criteria utilized to evaluate if antimicrobials are indicated in acute COPD exacerbation. A total of 6 observational studies met inclusion criteria for this meta-analysis. Sputum purulence was defined by visual assessment of color, either subjectively by providers and/or patients or by a colored chart, where green or yellow sputum was considered purulent. Four of the studies were primarily conducted in hospitalized patients, one in the emergency department, and one in the primary care setting. Five studies relied upon expectorated sputum and one used bronchoscopy to obtain sputum samples for bacterial cultures. Compared with mucoid sputum, purulent sputum had a significantly higher probability of positive bacterial culture results (RR = 2.14, 95%CI [1.25, 3.67], p = 0.006, moderate quality). For sensitivity analysis, after removal of studies losing 2 or more points from the New Castle-Ottawa scale, the effect value remained statistically significant. This systematic review and meta-analysis showed a moderate level of evidence that purulent sputum during COPD exacerbation, as defined by yellow or green color, is associated with a significantly higher probability of potentially pathogenic bacteria, supporting GOLD report and NICE recommendations.