No abstract

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.

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.

SummaryIn order to investigate the risk of fetal loss in carriers of factor V Leiden who are family members of probands with this mutation, we performed a retrospective cohort study including 109 women who had been pregnant at least once and were family members of 61 probands with venous thromboembolism and a single identified factor V Leiden mutation. The rate of pregnancies ending in unexplained fetal loss, early miscarriage, late miscarriage or stillbirth in women with the factor V Leiden was compared with that of women with normal genotype. In the 65 women who were carriers of factor V Leiden 31 of the 191 pregnancies (16.2% per pregnancy ) resulted in unexplained fetal loss, as compared to 13 of the 121 pregnancies (10.7% per pregnancy) in the 44 non-carriers (relative risk, 1.5; 95% CI, 0.8-3.2). After the first trimester of pregnancy, 25 pregnancies (13.1% per pregnancy) among carriers of factor V Leiden ended in fetal loss, as compared to 7 (5.8% per pregnancy) among females with normal genotype (relative risk, 2.3; 95% CI, 1.01 to 5.1). We conclude that carriers of factor V Leiden who are family members of probands with this mutation have a statistically significant and clinically important risk of late miscarriage or stillbirth. Studies addressing the benefit-to-risk ratio of adopting routinary thromboprophylactic measures following the first trimester of pregnancy in these women are strongly indicated.

Although pharmacologic prophylaxis against venous thromboembolism has become the standard of care following total hip and knee replacement, prophylaxis among patients undergoing surgery for hip fracture and other lower extremity trauma remains underutilized. Available experience consistently supports the view that low-molecular-weight heparins are more effective than unfractionated heparin for prevention of proximal deep vein thrombosis (DVT) with no additional hemorrhagic risk and more effective than oral anticoagulants for prevention of in-hospital (mostly distal) venous thrombosis at the price of a higher surgical site bleeding and wound hematoma. The choice between low-molecular-weight heparin and warfarin should be tailored to the individual patients based on the clinical assessment of postoperative thrombosis and bleeding risk as well as the prophylaxis-specific cost and convenience. Whether thromboprophylaxis should be continued for a few additional weeks after hospital discharge is controversial. The overall incidence of postoperative DVT in patients with cancer is about twice as high as that of patients free of malignancy. Accordingly, they require prophylactic measures comparable with those usually recommended for major orthopedic surgery. In this setting, dermatan sulfate shows promise. In contrast to surgical patients, prevention of venous thromboembolism is less well studied in hospitalized medical patients. In a recent controlled randomized trial, enoxaparin in high prophylactic doses was an effective and safe measure of thromboprophylaxis in ordinary bedridden patients.