The characteristics of the frequent exacerbator with chronic bronchitis phenotype and non-exacerbator phenotype in patients with chronic obstructive pulmonary disease: a meta-analysis and system review

BACKGROUND: Chronic obstructive pulmonary disease (COPD) patients with different phenotypes show different clinical characteristics. Therefore, we conducted a meta-analysis to explore the clinical characteristics between the non-exacerbator (NE) phenotype and the frequent exacerbator with chronic bronchitis (FE-CB) phenotype among patients with COPD. METHODS: CNKI, Wan fang, Chongqing VIP, China Biology Medicine disc, PubMed, Cochrane Library, and EMBASE databases were searched from the times of their inception to April 30, 2019. All studies that reported the clinical characteristics of the COPD phenotypes and which met the inclusion criteria were included. The quality assessment was analyzed by Cross-Sectional/Prevalence Study Quality recommendations. The meta-analysis was carried out using RevMan5.3. RESULTS: Ten cross-sectional observation studies (n = 8848) were included. Compared with the NE phenotype, patients with the FE-CB phenotype showed significantly lower forced expiratory volume in 1 s percent predicted (FEV(1)%pred) (mean difference (MD) -8.50, 95% CI -11.36–-5.65, P < 0.001, I(2) = 91%), forced vital capacity percent predicted (FVC%pred) [MD − 6.69, 95% confidence interval (CI) -7.73–-5.65, P < 0.001, I(2) = 5%], and forced expiratory volume in 1 s/forced vital capacity (FEV(1)/FVC) (MD -3.76, 95% CI -4.58–-2.95,P < 0.001, I(2) = 0%); in contrast, Charlson comorbidity index (MD 0.47, 95% CI 0.37–0.58, P < 0.001, I(2) = 0], COPD assessment test (CAT) score (MD 5.61, 95% CI 4.62–6.60, P < 0.001, I(2) = 80%), the quantity of cigarettes smoked (pack-years) (MD 3.09, 95% CI 1.60–4.58, P < 0.001, I(2) = 41%), exacerbations in previous year (2.65, 95% CI 2.32–2.97, P < 0.001, I(2) = 91%), modified Medical British Research Council (mMRC) score (MD 0.72, 95% CI 0.63–0.82, P < 0.001, I(2) = 57%), and body mass index (BMI), obstruction, dyspnea, exacerbations (BODEx) (MD 1.78, 95% CI 1.28–2.28, P < 0.001, I(2) = 91%), I(2) = 34%) were significantly higher in patients with FE-CB phenotype. No significant between-group difference was observed with respect to BMI (MD-0.14, 95% CI -0.70–0.42, P = 0.62, I(2) = 75%). CONCLUSION: COPD patients with the FE-CB phenotype had worse pulmonary function and higher CAT score, mMRC scores, frequency of acute exacerbations, and the quantity of cigarettes smoked (pack-years) than those with the NE phenotype.