Parameters:
(1) factor VIII level at presentation with thrombosis
(2) d-dimer level at presentation with thrombosis
(3) levels of factor VIII after standard duration anticoagulant therapy
(4) levels of d-dimer after standard duration anticoagulant therapy
Monitoring of patients was done:
(1) 3 months
(2) 6 months
(3) 12 months
(4) annually thereafter
Criteria for a poor thrombotic outcome:
(1) presence of residual thrombosis at 3 or 6 months after onset
(2) recurrent thromboembolism within 2 years in a previously unaffected venous system
(3) development of post-thrombotic syndrome
Criteria for identifying a child with a poor outcome:
(1) elevation of factor VIII and/or d-dimer at presentation with thrombosis
(2) persistent elevation of factor VIII and/or d-dimer 3-6 months after standard duration anticoagulant therapy
where:
• The upper limit of the normal reference range for Factor VIII levels was 1.5 IU/mL.
• The upper limit of the normal d-dimer level was 499 ng/mL.
