Search Strategy, Screening, and Identification

A comprehensive search strategy for MEDLINE (1946 to February 03, 2022) and EMBASE (1974 to 2022 February 03) databases was developed, and the Ovid interface used (Supplementary List 1). The search strategy was based on three elements: heterozygous FVL mutation (patients); recurrent VTE (outcome); and prospective cohort study (study design). The search strategy was improved using keywords found in key publications and no limits were applied. The sensitivity was tested in eight key publications (100%). The literature search was completed by hand search using reference lists of articles retrieved. All included studies were checked for published errata. The last search run was done on the fourth of February 2022. All records were carefully assessed for eligibility by screening of title, abstract and full text by two reviewers in duplicate (D.E., M.N.).