The characteristics of the frequent exacerbators with chronic bronchitis phenotype and the asthma-chronic obstructive pulmonary disease overlap syndrome phenotype in chronic obstructive pulmonary disease patients: A meta-analysis and system review

To investigate the difference of clinical characteristics between chronic obstructive pulmonary disease (COPD) patients with the frequent exacerbators with chronic bronchitis (FE-CB) phenotype and those with the asthma-COPD overlap syndrome (ACO) phenotype. We searched CNKI, Wan Fang, Chongqing VIP, China Biology Medicine disc, PubMed, Cochrane Library, and EMBASE databases for studies published as of April 30, 2019. All studies that investigated COPD patients with the FE-CB and ACO phenotypes and which qualified the inclusion criteria were included. Cross-sectional/prevalence study quality recommendations were used to measure methodological quality. RevMan5.3 software was used for meta-analysis. Ten studies (combined n = 4568) qualified the inclusion criteria. The FE-CB phenotype of COPD was associated with significantly lower forced vital capacity percent predicted (mean difference [MD] −9.05, 95% confidence interval [CI] [−12.00, −6.10], P < .001, I(2) = 66%), forced expiratory volume in 1 second (FEV(1)) (MD −407.18, 95% CI [−438.63, −375.72], P < .001, I(2) = 33%), forced expiratory volume in 1 second percent predicted (MD −9.71, 95% CI [−12.79, −6.63], P < .001, I(2) = 87%), FEV(1)/forced vital capacity (MD −5.4, 95% CI [−6.49, −4.30], P < .001, I(2) = 0%), and body mass index (BMI) (MD −0.81, 95% CI [−1.18, −0.45], P < .001, I(2) = 44%) as compared to the ACO phenotype. However, FE-CB phenotype was associated with higher quantity of cigarettes smoked (pack-years) (MD 6.45, 95% CI [1.82, 11.09], P < .001, I(2) = 73%), COPD assessment test score (CAT) (MD 4.04, 95% CI [3.46, 4.61], P < .001, I(2) = 0%), mMRC score (MD 0.54, 95% CI [0.46, 0.62], P < .001, I(2) = 34%), exacerbations in previous year (1.34, 95% CI [0.98, 1.71], P < .001, I(2) = 68%), and BMI, obstruction, dyspnea, exacerbations (BODEx) (MD 1.59, 95% CI [1.00, 2.18], P < .001, I(2) = 86%) as compared to the ACO phenotype. Compared with the ACO phenotype, COPD patients with the FE-CB phenotype had poorer pulmonary function, lower BMI, and higher CAT score, quantity of cigarettes smoked (pack-years), exacerbations in previous year, mMRC score, and BODEx. This study is an analysis of published literature, which belongs to the second study. Therefore, this study does not require the approval of the ethics committee. The findings will be disseminated through a peer-reviewed journal publication or conference presentation.