Study selection and data extraction
Two reviewers independently conducted screening and data extraction, with any differences resolved by consultation with a third reviewer. After removing duplicate articles, two reviewers screened the titles and abstracts according to the inclusion criteria and then determined the final studies for inclusion by reading the full text.
A predesigned table was used to collate the extracted data. One reviewer independently extracted data, and an expert verified the content. The data that were extracted from each publication included: (1) details of the study, such as the year of publication, study design, name of the first author, and country (2) characteristics of the population, such as their age and cigarettes smoked per day; (3) details of the intervention, such as the drug name, dose, and duration of treatment); (4) treatment outcomes, including the number of people who successfully quit smoking and any adverse reactions.