A systematic review and meta-analysis of the herbal formula Buzhong Yiqi Tang for stable chronic obstructive pulmonary disease.

OBJECTIVE: To systematically evaluate the efficacy and safety of Buzhong Yiqi Tang (BZYQT) for stable chronic obstructive pulmonary disease (COPD).

METHODS: Three electronic English databases (PubMed, EMBASE and CENTRAL) and four Chinese databases (CBM, CNKI, CQVIP and WFMO) were searched from their inceptions until 30th June 2016. Participants were diagnosed with COPD according to the Chinese Medical Association's COPD diagnosis and treatment guidelines or Global Initiative for Chronic Obstructive Lung Disease (GOLD), and were in stable stage. Randomized controlled trials (RCTs) of oral BZYQT, alone or combined with conventional treatment, compared with conventional treatment alone or plus placebo were included in the review. Clinical improvement and the six-minute walking test (6MWT) were the primary outcome measures. The secondary outcome measures were defined as forced expiratory volume in one second (FEV1), forced vital capacity (FVC), respiratory muscle strength index with maximum inspiratory pressure (MIP), COPD Assessment Test (CAT), and frequency of acute exacerbations. To assess risk of bias the Cochrane, Risk of Bias tool was used, and statistical analysis was performed using RevMan 5.3.0 software.

RESULTS: Sixteen studies (1400 participants) were included. The results of meta-analysis indicated patients receiving BZYQT alone or BZYQT in combination with conventional treatment showed a significant increase in clinical improvement (RR 1.25, 95% CI 1.18 to 1.33, I(2)=0%), enhanced exercise capacity 6MWT (MD 51.22m, 95% CI 45.56 to 56.89, I(2)=44%), improved lung function FVC (L) (MD 0.26 liters, 95% CI 0.18 to 0.33, I(2)=37%), reduced respiratory muscle fatigue MIP (MD 0.46 liters, 95% CI 0.11 to 0.80, I(2)=0%), and improved quality of life CAT (MD -2.56 points, 95% CI -3.40 to -1.72, I(2)=0%) when compared with conventional treatment alone, or plus placebo. BZYQT also showed small but significant improvements in FEV1% and decreased acute exacerbations of COPD. Four studies reported that no adverse events occurred, other studies did not mention adverse events. The finding should be considered with caution because the included studies had methodological shortfalls.

CONCLUSIONS: BZYQT improves clinically important outcomes for patients with stable COPD, such as improved clinical symptoms, exercise capacity, lung function and quality of life. Moreover, it has an excellent safety profile. However further evaluation is needed to validate these preliminary findings in high quality RCTs.