Limitations
This study has the following limitations: 1) Limited by the search
language and authority, we only searched English literature, and may
miss some studies that meet the inclusion criteria, which may lead to
potential publication bias or language bias. 2) Limited by the search
time, new trials may appear in the future, which may lead to changes in
the current research results, and we will update it in two years. 3)
Different clinical trial studies have different reports on the outcomes
of quitting smoking. Some studies use cotinine-confirmed prolonged
smoking abstinence, while others use the 7-day point prevalence
abstinence. The differences in the reporting methods of quitting smoking
outcomes may affect the summary results. Therefore, it is necessary to
carefully evaluate the combined effect. 4) A further subgroup analysis
was not conducted, we cannot clearly assess the impact of some variables
on the current level of evidence. Due to the limited number of studies
on specific drugs, we did not analyze the potential effects of age,
smoking status, alcohol consumption, drug dosage, duration, etc. on the
outcome of smoking cessation.