Long term effects of Vernonia cinerea on continuous abstinence rate of smoking cessation: a subgroup analysis of meta-analysis

Abstract

INTRODUCTION: Smoking is related to several diseases. Vernonia cinerea (VC) has been shown to be an effective treatment for smoking cessation. A recent meta-analysis found that using of VC in various methods provided continuous abstinence rate (CAR) of 1.54 (95% confidence interval 1.06, 2.23). However, that meta-analysis did not have data on long-term CAR outcomes of VC tea. This study aimed to perform a subgroup analysis of the update meta-analysis to show the long term effects of VC tea on smoking cessation. EVIDENCE ACQUSITION: This study was a subgroup analysis of the previous meta-analysis. The inclusion criteria were randomized controlled trials comparing VC tea versus other controls in smoking cessation. The primary outcome was continuous abstinence rate (CAR) at both short and long term periods. Searching was performed in the following sources: PubMed, Science Direct, Web of Science, Thai-Journal Citation Index Center (TCI), ThaiLis and references of selected articles. CAR at week 2 to week 24 between the VC tea and control were compared and calculated for risk ratio with 95% confidence interval. EVIDENCE SYNTHESIS: There were four eligible studies, but one study was excluded as the outcomes were not CAR. The three studies were conducted in Thailand; Udonthani, Chonburi, and Pathum thani. At four weeks after a two-week of VC intervention (2 studies) and four-week of VC intervention (1 study), a risk ratio for smoking cessation was 1.68 (95% confidence interval of 1.15, 2.47). At week 24, both intention to treat and per protocol analysis found non-significant increasing trend by VC over control group. The risk ratios of both analyses were 1.44 and 1.28, respectively. CONCLUSIONS: VC tea had acute delayed effects of smoking cessation but had no effect in the long term period at week 24.