Published online Aug 28, 2020. doi: 10.13105/wjma.v8.i4.345
Peer-review started: May 20, 2020
First decision: July 4, 2020
Revised: July 4, 2020
Accepted: August 15, 2020
Article in press: August 15, 2020
Published online: August 28, 2020
Core Tip: This letter call for the use of contextual variables, that are typically not in use for covariate analyses. Contextual variables are introduced and defined as variables not immediately/directly measured by the original studies in the meta-analysis but rather can be estimated knowing the background of each study. For example in a meta analysis of clinical trails one might want to adjust for studies from high income vs low income countries or studies that were funded vs independent.