Objective: Conduct a systematic review and meta-analysis on the effectiveness and safety of varenicline in smokeless tobacco (SLT) cessation.
Methods: PubMed, EMBASE, clinicaltrials.gov, and the Cochrane Registry were searched up to February 1, 2014, for randomized clinical trials (RCTs) comparing varenicline to placebo. Random effects Mantel-Haenszel summary relative risks (RRs), risk difference (RD), and 95% CIs were used for analysis and reporting of outcomes. Primary and secondary outcomes were the 7-day point prevalence of SLT abstinence at the end of 12 and 26 weeks, respectively. Adverse events reported include nausea, sleep disturbance, and mood disorders.
Results: Three published RCTs involving 744 SLT users with a mean age of 39.7 years, of which greater than 88% were males, were randomized to varenicline (n = 370) and placebo (n = 374). Subjects in the varenicline arm had a significantly higher 7-day point prevalence of SLT abstinence at 12 weeks (48% vs. 33%; RR = 1.45, 95% CI = 1.22-1.72, p < .0001, I2 = 0%; RD = 13%, 95% CI = 4%-23%, p = .008) but not at 26 weeks (49% vs. 39%; RR = 1.38, 95% CI = 0.93-2.03, p = .11, I2 = 51%). There were no statistically significant differences in the incidences of adverse events between the 2 arms but interpretation is limited by high heterogeneity.
Conclusion: This pooled analysis suggests that varenicline is effective in achieving a 7-day point prevalence of SLT abstinence at 12 weeks but showed that this effect was not sustained at 26 weeks.
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