FIDO Investigators

Fixed-dose, weight-adjusted, subcutaneous unfractionated heparin vs. low-molecular-weight heparin for acute treatment of VTE (2006)


Treatment of acute DVT and PE

Close this section


To determine if fixed-dose, weight-adjusted, subcutaneous UFH is as effective and safe as subcutaneous LMWH for the treatment of acute VTE

Close this section

Trial design

Randomized, open-label, non-inferiority study with parallel groups
Active treatment: UFH, initial 333 IU/kg s.c., followed by a fixed dose of 250 IU/kg s.c. every 12 hours, without subsequent use of coagulation tests to modify those doses, for at least 5 days and until INR >2.0 (n=345)
Control treatment: dalteparin or enoxaparin 100 IU/kg s.c. every 12 hours for at least 5 days and until INR >2.0 (n=352)
Both treatments could be administered out of hospital and both were overlapped with 3 months of warfarin therapy

Close this section


Primary efficacy endpoint: recurrent VTE during 3-month follow-up
Primary safety endpoints: major bleeding within 10 days of randomization
Secondary endpoints: hospital stay

Close this section

Trial participants

708 patients (mean age 60 years) with newly diagnosed symptomatic or asymptomatic DVT of the legs or symptomatic PE. Of the randomized patients, 11 were subsequently excluded from the analysis of efficacy and 8 from the analysis of safety

Close this section


Efficacy outcome: During the 3-month follow-up, recurrent VTE occurred in 13 of 345 patients (3.8%) in the UFH group as compared with 12 of 352 patients (3.4%) in the LMWH group. 2 patients in the UFH group and 4 patients with LMWH had PE, the remaining episodes were DVT
Safety outcome: Major bleeding complications occurred during the first 10 days in 4 of 348 patients given UFH (1.1%) and 5 of 352 patients in the LMWH group (1.4%). At 3 months, the rates were 1.7% and 3.4%, respectively. 18 patients (5.2%) assigned to UFH and 22 patients (6.3%) assigned to LMWH died
Hospital stay: Treatment was administered entirely out of hospital in 72% of the UFH group and 68% of the LMWH group

Close this section


Efficacy: Fixed-dose, unmonitored, subcutaneous UFH is as effective as fixed-dose, unmonitored, subcutaneous dalteparin or enoxaparin in patients with acute VTE and is suitable for treatment at home
Safety: Total bleeding, which included major and minor bleeding, was not significantly different between both groups

Close this section


Kearon C, Ginsberg JS, Julian JA, Douketis J, Solymoss S, Ockelford P, Jackson S, Turpie AG, MacKinnon B, Hirsh J, Gent M, for the Fixed-Dose Heparin (FIDO) Investigators. Comparison of fixed-dose weight-adjusted unfractionated heparin and low-molecular-weight heparin for acute treatment of venous thromboembolism. J Am Med Ass 2006;296:395-342

Close this section

Corresponding author

Clive Kearon, MB, PhD, Hamilton Health Sciences, Henderson Division, 711 Concession St, Hamilton, Ontario, Canada L8V 1C3, e-mail:

Close this section

Back To List

Recommend pageBack to top