Women who met two or more criteria and all men were classified as high risk.
We then applied the HERDOO2 clinical decision rule.
Consecutive unselected patients at 44 secondary and tertiary care centres in seven countries (see supplementary appendix) were asked to participate if they had a first episode of major, symptomatic, objectively proved unprovoked VTE 5-12 months before enrolment (referred to as the index VTE).
Index VTE was defined as unprovoked, in line with other studies,181920 in the absence of the following major VTE provoking factors: leg fracture or lower extremity plaster cast, immobilisation for more than three days, major surgery in the three months before the index VTE event, and no diagnosis of a malignancy in the past five years (with the exception of localised skin malignancy).
The baseline assessment took place 5-12 months after the index VTE event, while patients were still receiving oral anticoagulant treatment.
We documented demographic data, causes, and diagnostic or therapeutic management of the index VTE event.
In the primary analysis, 17 low risk women who discontinued anticoagulants developed recurrent VTE during 564 patient years of follow-up (3.0% per patient year, 95% confidence interval 1.8% to 4.8%).