Network meta-analysis
The result of network meta-analysis was shown in figure 4. The final network effect showed that the comparisons with a statistically different including Varenicline vs Placebo (OR=4.90, 95%CI [1.77,13.55]), Varenicline vs Naltrexone (OR=3.50, 95%CI [1.13,11.06]), and Varenicline vs Bupropion (OR=3.32, 95%CI [1.03,10.74]). This signified that compared with placebo, Naltrexone, and Bupropion, Varenicline had an evident superiority in quitting smoking. The comparison between any other interventions did not show a significant difference.