Clinical Indicators for Asthma-COPD Overlap: A Systematic Review and Meta-Analysis
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Junjie Peng1, Min Wang1, Yanqiu Wu1
1Department of Respiratory and Critical Care Medicine, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, People's Republic of China.
Background:
Some clinical indicators have been reported to be useful in differentiating asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) from pure asthma/COPD, but the results were inconsistent. This study aims to evaluate the diagnostic value of these indicators for ACO.
Methods:
Databases of PubMed, EMBASE, Ovid and Web of Science were retrieved. Pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated in random-effects models.
Results:
48 eligible studies were included. The pooled results indicated, compared with pure asthma, ACO patients had lower levels of forced expiratory volume in the first second (FEV1)% predicted (pred) (SMD=-1.09, 95% CI -1.3 to -0.87), diffusion lung capacity for carbon monoxide (DLCO)% pred (SMD=-0.83, 95% CI -1.24 to -0.42), fractional exhaled nitric oxide (FeNO) (SMD=-0.23, 95% CI -0.36 to -0.11), and higher levels of induced sputum neutrophil (SMD = 0.51, 95% CI 0.21 to 0.81), circulating YKL-40 (SMD = 0.96, 95% CI 0.27 to 1.64). However, relative to COPD alone, ACO patients had higher levels of FEV1% pred (SMD = 0.15, 95% CI 0.05 to 0.26), DLCO% pred (SMD = 0.38, 95% CI 0.16 to 0.6), FeNO (SMD = 0.59, 95% CI 0.40 to 0.78), serum total immunoglobulin (Ig)E (SMD = 0.42, 95% CI 0.1 to 0.75), blood eosinophil (SMD = 0.44, 95% CI 0.29 to 0.59), induced sputum eosinophil (SMD = 0.62, 95% CI 0.42 to 0.83), and lower levels of induced sputum neutrophil (SMD=-0.48, 95% CI -0.7 to -0.27), circulating YKL-40 (SMD=-1.09, 95% CI -1.92 to -0.26).
Conclusion:
Compared with pure asthma/COPD, ACO patients have different levels of FEV1% pred, DLCO% pred, FeNO, serum total IgE, blood eosinophil, induced sputum eosinophil/neutrophil, and circulating YKL-40, which could be helpful to establish a clinical diagnosis of ACO.
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