Study selection and data abstraction
The titles and abstracts of the studies acquired from the electronic
databases were examined separately by two reviewers. Subsequently, we
selected the eligible studies after the full-text screenings based on
the pre-defined inclusion criteria. Conflicts were settled by the
conversation between the two reviewers or communication with the
relevant authors. The following data of the included studies were
abstracted: study characteristics (first author, year of publication,
study design), study population, and baseline characteristics (study
period, demographic, sample size, age, female ratio, definition of
polypharmacy, follow-up period), effectiveness and safety outcomes,
confounders, and outcome data (sample size and the number of events
between groups, adjusted HRs).