Predictors of acute exacerbations in COPD: a systematic review

Background: Acute exacerbations in COPD (AECOPD) contribute to decreased quality of life, increased functional impairment and mortality. Aim: To identify predictors of AECOPD that could facilitate early recognition and subsequent initiation of appropriate treatment. Methods: A systematic review including studies on predictors of AECOPD was conducted. Patient characteristics, biomarkers, lung function parameters, symptoms, and composites thereof were considered. Predictors were defined as variables having a statistically significant predictive value for AECOPD (p<0.05). Outcome measures of interest were moderate and severe AECOPD. Study quality was assessed using the QUIPS tool. Results: Out of 909 abstracts, 193 articles entered full text screening. 21 articles reporting 18 studies were included. There were 33 predictors out of 70 reported variables: 10 patient characteristics (e.g., daily physical activity, BMI, smoking), 6 biomarkers (e.g., sarcopenia index, eosinophil count, neutrophil-lymphocyte ratio), 6 lung function parameters (e.g., gas trapping, inspiratory capacity, exercise induced desaturation), 6 symptoms (e.g. chronic cough, mMRC, Pittsburgh Sleep Quality Index), and 5 composites (e.g., BODE, BODEx). Only 10 of the predictors were significant in >1 study: AECOPD in previous year, age, gender, 6MWD, FEV1% of predicted, GOLD A-D and GOLD I-IV classification, CAT, SGRQ-C and Clinically Important Deterioration. The reviewers judged 14 articles as having high, 3 moderate and 4 low risk of bias. Conclusion: This systematic review identified 33 predictors of AECOPD, only 10 were significant in >1 study. Future studies should focus on the validation of earlier observed predictors of AECOPD and study quality.