Efficacy of Vernonia cinerea (L) Less for smoking cessation: An updated meta-analysis of randomized controlled trials

Vernonia cinerea (VC) has been used for smoking cessation. A previous meta-analysis (MA) reported the efficacy of VC in smoking cessation. However, there have been updated randomized controlled trials (RCTs) on the efficacy of VC for smoking cessation, and the previous MA lacked pooled adverse events (AEs) related to VC. The objective of this study was to systematically review and perform an updated MA on the efficacy of VC for smoking cessation continuous abstinence rate (CAR), prevalence abstinence (PAR), and AE. The research articles were retrieved via electronic databases including PubMed, Science Direct, Web of Science, Thai-Journal Citation Index Center (TCI), and ThaiLis. Ten RCTs published prior to 2019 were included in this study. The number of participants in the studies ranged from 35 to 172, and the follow-up duration for the primary outcomes was 2-12 weeks. Our updated MA found that VC could significantly improve CAR2 (RR=1.54; 95% CI = 1.06, 2.23), CAR4 (RR=1.65; 95% CI = 1.25, 2.17), CAR 8 (RR=1.85; 95% CI = 1.25, 2.75), CAR12 (RR=2.56; 95% CI = 1.66, 3.95), and CAR16 (RR=2.21; 95% CI = 1.03, 4.73). Moreover, VC improved PAR2 (RR=1.47; 95% CI = 1.06, 2.04), PAR4 (RR=1.35; 95% CI = 1.02, 1.79), PAR8 (RR=1.60; 95% CI = 1.11, 2.31), and PAR12 (RR=1.70; 95% CI = 1.25, 2.30). There was no significant difference in the AE between the two groups. The study substantiates claims that VC products are effective in assisting with smoking cessation.