Search strategy
Online databases including PubMed, Cochrane Library, Web of Science, Embase, and Google Scholar were searched from inception to January 2021 to identify relevant studies. In addition, supplementary searches were conducted through the WHO International Clinical Trials Registry Platform (ICTRP) search portal and grey literature. The main search strategies were as follows: (smok* OR cigarette OR tobacco OR nicotine) AND (Alcohol* OR drink) AND (cessation OR quit* OR abstinence OR stop*) AND (drug OR medicine OR pharmaco*) AND (“random*” OR “blind*” OR “single-blind*” OR “double-blind*” OR “treble-blind*” OR “triple-blind*”).
Inclusion and exclusion criteria
Only randomized controlled trials (RCTs) were included. The inclusion criteria were as follows: 1) Population: smokers with alcohol dependence; 2) Intervention: the experimental group accepted pharmacotherapies and the control group received a placebo; 3) Outcomes: only the indicators related to smoking were included, such as smoking cessation rate and changes in the number of cigarettes per day.
Studies that were duplicate reports or with insufficient data, such as protocols, conference proceedings, or abstracts, were excluded. Studies written in languages other than English were not included.