RT Journal Article SR Electronic T1 Dealing with categorical risk data when extracting data for meta-analysis JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP 43 OP 45 DO 10.1136/bmjebm-2020-111649 VO 26 IS 2 A1 Taylor, Kathryn S A1 Mahtani, Kamal R A1 Aronson, Jeffrey K YR 2021 UL http://ebm.bmj.com/content/26/2/43.abstract AB