Study characteristics
As shown in Table 1, the included RCTs involved 1565 alcohol-drinking
smokers (803 in treatment groups and 762 in control groups). All studies
were published between 2005 and 2020 in the United States (n = 13),
United Kingdom (n = 1) and Canada (n = 1). Most smokers were over 40
years of age and smoked more than ten cigarettes per day. All studies
were the two-arm design and the treatment group in each RCT examined one
of six drugs, including Varenicline (n = 5), Naltrexone (n = 4),
Topiramate (n = 2), Bupropion (n = 3), and Baclofen (n = 1), meanwhile
all RCTs gave a placebo to the control group. The duration of the
measurement phase ranged from four weeks to 52 weeks, and the smoking
cessation rate was the outcome indicator of all studies, including 7-day
point prevalence abstinence, prolonged (continuous) abstinence, and
other point prevalence abstinence (direct reports at each stage).