Table 2.

Recurrence rates and hazard ratios according to predictor variables.

Predictor variable	Events (numbers)	Incidence rate per 100 patient-years (95%CI)	Hazard ratio* (unadjusted; 95%CI)	Points attributed in the prediction model‡
All patients	64	2.9 (2.2, 3.7)	N/A
Unprovoked DVT	47	4.0 (3.0, 5.3)	3.1 (1.3, 7.4)	2
Male sex	41	3.9 (2.9, 5.3)	2.0 (1.2, 3.3)	1
Elevated D-dimer+	26	5.1 (3.4, 7.4)	2.5 (1.5, 4.3)
High factor VIII+	17	5.2 (3.2, 8.3)	2.3 (1.3, 4.2)	2
Presence of inflammation	15	4.7 (2.9, 7.9)	1.9 (1.1, 3.4)

^*Cox proportional hazards model adjusted for periods of anticoagulation by including this variable as a time-varying co-variable; + assessed 1 month after stop anticoagulation treatment;

^‡patients will be categorized into three groups: low risk (score 0), medium risk (scores 1, 2, or 3) and high risk (scores 4 and 5).