SummaryPerioperative anticoagulant prophylaxis for postoperative venous thromboembolism (VTE) in neurosurgical patients has not gained wide acceptance due to the fear of intracranial bleeding. Physical methods give a worthwhile reduction of postoperative VTE but there still remains a substantial residual incidence. In other clinical indications, low molecular weight heparins have proven to be effective for prophylaxis of VTE when administered postoperatively, with the advantage of no bleeding enhancement during surgery.Therefore, we performed a multicentre, randomized, double-blind trial in neurosurgical patients to investigate the efficacy and safety of adding a low molecular weight heparin (LMWH), nadroparin, initiated postoperatively, to graduated compression stockings in the prevention of VTE. Deep-vein thrombosis was detected by mandatory venography. Bleeding was determined according to pre-defined objective criteria for major and minor episodes.An adequate bilateral venogram was obtained in 166 of 241 LMWH patients (68.9%) and 179 of 244 control patients (73.4%). A total of 31 of 166 LMWH patients (18.7%) and 47 of 179 control patients (26.3%) had VTE up to Day 10 postoperatively (p = 0.047). The relative risk reduction (RRR) was 28.9%. The rates for proximal deep-vein thrombosis/pulmonary embolism were 6.9% and 11.5% for the two groups, respectively (RRR: 40.2%; p = 0.065).Secondary analyses involved all VTE up to day 56 post-surgery which was detected in 33 patients of 241 in the LMWH group (13.7%) and 51 of 244 control patients (20.9%; RRR 34.5%; p = 0.018). The corresponding percentages for proximal deep-vein thrombosis/pulmonary embolism were 5.8% and 10.2% for the two groups, respectively, giving a RRR of 43.3%; p = 0.036. Major bleeding complications, during the treatment period, occurred in six low molecular weight heparin treated patients (2.5%) and in two control patients (0.8%); p = 0.087.A higher mortality was observed in the low molecular weight heparin group over the 56-day follow-up period (22 versus 10; p = 0.026). However, none of these deaths was judged by a blinded adjudication committee to be related to the study drug.In conclusion, this study demonstrates that the low molecular weight heparin, nadroparin, added to graduated compression stockings results in a clinically significant decrease in VTE without inducing any significant increase of major bleeding.

The development of antibodies to factor VIII (inhibitors) in response to clotting-factor concentrates administration in hemophilia is common during the first few years of treatment but rare in multitransfused patients. We have investigated the possible association of a recently introduced factor VIII concentrate (Factor VIII CPS-P) in The Netherlands with the occurrence of inhibitors. To this effect, we conducted two studies. First, we performed a national multicenter study in which clinical information and inhibitor test results were obtained for 447 hemophilia A patients over the period 1988 through 1991. Secondly, for a baseline comparison we estimated the frequency of inhibitor development in a closely followed cohort of 144 patients, from 1984 through 1989. Before the introduction of Factor VIII CPS-P, the incidence of new inhibitors was 4.4/1,000 patient-years in the national study from March 1988 through May 1990, and 3.9/1,000 patient- years in the cohort followed from 1984 through 1989. These figures are similar to the incidence of new inhibitors that was found in a large cohort of patients in the United States followed in the 1970s. In the period that the new concentrate Factor VIII CPS-P was on the market, from June 1990 through November 1991, 11 clinically relevant inhibitors were detected, which yielded an incidence over this interval of 20.1/1,000 patient-years, a 4.5-fold increase compared with the previous interval (C195: 1.4 to 14.3). Nine of these 11 patients had in their lifetime received over 250 infusions with factor VIII preparations. whereas all of the inhibitors detected in the previous time interval, and all of the 24 inhibitor patients described in the US study, had received less than 250 infusions in their lifetime. All patients who developed inhibitors after June 1990 had been exposed to Factor VIII CPS-P, whereas only 75% of the patients who did not develop an inhibitor had been exposed to this product. In a prospective extension of the study, with a second inhibitor measurement after 3 months, we found that one additional inhibitor had developed during 52.5 patient-years of Factor VIII CPS-P use. In conclusion, there has been a sudden increase in the frequency of inhibitor patients, for a large part among multitransfused patients. It seems more than likely that this increase is associated with the introduction of a new factor VIII concentrate in The Netherlands.(ABSTRACT TRUNCATED AT 400 WORDS)

Low-molecular-weight heparin in the treatment of patients with venous thromboembolism Büller, H.R.; Gent, M.; Gallus, A.S.; Ginsberg, J.; Prins, M.H.; Baildon, R.; ten Cate, J.W.

SummaryThe effect of induced hypothyroidism on platelet count and platelet volume distribution was studied in twelve athyreotic patients, After a two weeks withdrawal of triiodothyronine supplementation, platelet count and the ratio between platelet and red cell count were increased in all patients. Furthermore, mean platelet volume was declined and platelet distribution width was risen. Thus, hypothyroidism appears to increase the number of circulating platelets, especially the smaller ones.

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