Summary of results
In this network meta-analysis, 15 studies covering 1565 patients were
included. We evaluated the effectiveness and safety of some drugs
(varenicline, naltrexone, baclofen, topiramate and bupropion) in
quitting smoking for drinking smokers. The results of network
meta-analysis showed that in all 15 pairwise comparisons (including
direct and indirect comparison), only Varenicline showed smoking
cessation effect compared with Placebo, Naltrexone, and Bupropion, no
significant statistical difference was shown in the comparisons between
other drugs or placebo. Meanwhile, the results of traditional
meta-analysis showed that compared with Placebo, only Varenicline had
obvious superiority in quitting smoking. Based on the above analysis,
the value of Varenicline for smoking
cessation is worth exploring. Judging from the current clinical
evidence, many systematic reviews have explored the effect of smoking
cessation on Varenicline. However,
for the definition of the population, some reviews did not clearly
divide it, or focused on other types of populations (such as
cardiovascular smokers, schizophrenia smokers, etc.). For example, an
updated meta-analysis performed in 2015 by Kishi, T et al. explored the
effects of varenicline adjuvant therapy for smoking cessation in people
with schizophrenia, 36 the results suggested that
although varenicline adjuvant therapy was well tolerated, varenicline
was not superior to placebo in smoking cessation. Another systematic
review published by Wu, Q et al. determined the effectiveness and safety
of varenicline in treating tobacco dependence in patients with severe
mental illness, the author pointed out that Varenicline appeared to be
significantly more effective than placebo in assisting with smoking
cessation. 37 From the conclusions of the above two
reviews, the characteristics of the population seem to play an important
role in the effect of smoking cessation. Therefore, for drinking
smokers, we still need to interpret the existing conclusions carefully.
As for the methodological quality of the included studies, although
there are no ”high risk of bias ” studies, the risk of bias results of
more than half of the studies are ”unclear risk of bias ”, so the
methodological quality of these randomized controlled trials is low. Due
to the random sequence generation, allocation concealment, and blinding
for all people are important design steps of RCT, however, the
description information of these three items is unclear, eventually an
unclear risk bias is generated. There is no doubt that potential risk
bias will reduce the quality of evidence. At the same time, we should
consider the impact of other factors on the quality of evidence. For
inconsistency, due to no closed loop was formed in the network diagram,
thus we did not perform inconsistency test. However, precision,
heterogeneity, and publication bias may reduce the level of evidence for
some interventions. For example, in network meta-analysis, Varenicline
showed statistical differences compared with Placebo, Naltrexone, and
Bupropion, but they all had a wide confidence interval (imprecision).
Moreover, in traditional meta-analysis, we found high statistical
heterogeneity in Topiramate vs Placebo
(I 2=69%). Due to few studies, we did not
explore publication bias, but we cannot completely ignore the impact of
this factor on the level of evidence.