Prolonged thromboprophylaxis with oral anticoagulants after total hip arthroplasty: a prospective controlled randomized study.

BACKGROUND: The optimal duration of thromboprophylaxis after major orthopedic surgery is controversial. Although oral anticoagulants are still widely used for the prevention of venous thromboembolism after hip replacement, to our knowledge no study has assessed the benefit of prolonging anticoagulation beyond the hospital stay. METHODS: Consecutive patients who had received warfarin sodium prophylaxis after total hip arthroplasty were randomized to stop taking the drug at the time of hospital discharge or to continue taking it for 4 more weeks. The rate of symptomatic and asymptomatic venous thromboembolic events (as shown by compression ultrasonography of the proximal-vein system) occurring during the study period was compared between the 2 groups. The study was prematurely terminated after the inclusion of the first 360 patients because a statistically significant and clinically relevant superiority of extended over short-term thromboprophylaxis was observed. RESULTS: Objectively confirmed venous thromboembolic complications were recorded in 10 patients: 9 (5.1%) in the group of 176 control patients, and 1 (0.5%) in the group of 184 patients who continued the warfarin treatment. The absolute difference in the incidence of events was 4.57% (95% confidence interval [CI], 1.15-7.99). The relative risk of venous thromboembolism developing in control patients compared with patients assigned to extended thromboprophylaxis was 9.4 (95% CI, 1.2-73.5). The number needed to treat was 22. Major bleeding developed in 1 patient who was randomized to the extended prophylaxis group (0.5%; 95% CI, 0.02-3.0) compared with none in the control group. CONCLUSION: Extending prophylaxis with warfarin for a few more weeks beyond the hospital stay has the potential to considerably improve the outcome of patients who undergo hip arthroplasty.

The incidence of heparin-induced thrombocytopenia in hospitalized medical patients treated with subcutaneous unfractionated heparin: a prospective cohort study.

Although heparin-induced thrombocytopenia (HIT) is a known complication of intravenous unfractionated heparin (UFH), its incidence in medical patients treated with subcutaneous UFH is less well defined. To determine the incidence of HIT in this category of patients, the platelet count was performed at baseline and then every 3 +/- 1 days in 598 consecutive patients admitted to 2 medical wards and treated with subcutaneous UFH for prophylactic (n = 360) or therapeutic (n = 238) indications. The diagnosis of HIT was accepted in the case of a platelet drop of 50% or more and either the demonstration of heparin-dependent antibodies or (when this search could not be performed) the combination of the following features: (1) the absence of any other obvious clinical explanation for thrombocytopenia, (2) the occurrence of thrombocytopenia at least 5 days after heparin start, and (3) either the normalization of the platelet count within 10 days after heparin discontinuation or the earlier patient's death due to an unexpected thromboembolic complication. HIT developed in 5 patients (0.8%; 95% CI, 0.1%-1.6%); all of them belonged to the subgroup of patients who received heparin for prophylactic indications. The prevalence of thromboembolic complications in patients with HIT (60%) was remarkably higher than that observed in the remaining 593 patients (3.5%), leading to an odds ratio of 40.8 (95% CI, 5.2-162.8). Although the frequency of HIT in hospitalized medical patients treated with subcutaneous heparin is lower than that observed in other clinical settings, this complication is associated with a similarly high rate of thromboembolic events.