Efficacy and safety of anticoagulant prophylaxis to prevent venous thromboembolism in acutely ill medical inpatients: a meta‐analysis

Abstract

Abstract. Själander A, Jansson J-H, Bergqvist D, Eriksson H, Carlberg B, Svensson P (Sundsvall Hospital, Sundsvall; Skellefteå Hospital, Skellefteå; Uppsala University Hospital, Uppsala; Sahlgrenska University Hospital, Ö stra, Göteborg; Umeå University Hospital, Umeå; and Malmö University Hospital, Malmö; Sweden). Efficacy and safety of anticoagulant prophylaxis to prevent venous thromboembolism in acutely ill medical inpatients: a meta-analysis. J Intern Med 2008; 263: 52-60.Objectives. Venous thromboembolism (VTE) is a potentially serious complication of hospitalization and immobilization. The use of anticoagulant prophylaxis in acutely ill medical inpatients is still under debate. New data including a recent meta-analysis have recently been published. We aim at studying the efficacy and safety of anticoagulant prophylaxis in acutely ill medical inpatients, and demonstrate differences between meta-analyses due to different data extraction from the heterogeneous studies included.Subjects. The Cochrane Library, MEDLINE and EM-BASE were searched from 1980 to present. Manual searches were performed regarding abstracts from major meetings. Seven blinded randomized controlled clinical trials assessing the prophylactic effect of heparin in acutely ill medical patients were identified and included in the meta-analysis.Results. Low-molecular weight heparin (LMWH) prophylaxis prevented 48% of symptomatic pulmonary embolism (PE), 48% of symptomatic deep vein thrombosis (DVT) (not significant) and 51% of asymptomatic DVT. A nonsignificant trend towards higher bleeding risk during LMWH prophylaxis was found. Death was not significantly affected. We compared our data with a recent meta-analysis with different study selection and data extraction and found similar results.Conclusions. As DVT and PE are manifestations of the same illness, VTE, one can argue that anticoagulant prophylaxis prevents approximately half of the expected events. Most medical inpatients have short hospital stays, and a low risk of VTE. The important task for the clinician is to identify patients with a sufficiently high risk of symptomatic VTE to warrant LMWH prophylaxis. Despite differences in study selection and data extraction, our study shows results similar to a recent meta-analysis.

Risk factors for first venous thromboembolism around pregnancy: a population-based cohort study from the United Kingdom

“…One way of assessing this could be calculating the number needed to treat (NNT) and number needed to harm from our data. For instance, if we were to assume that prophylaxis reduces the risk for VTE by 50%, as has been reported in trials outside of pregnancy, 36 then based on our estimate of the AR, 89 VTE events could be prevented per year in women whose pregnancies end in caesarean delivery (NNT, 1980). These values should be interpreted with caution, as they are based on speculative data regarding the reduction in risk resulting from LMWH, from which there is an absence of RCT data in pregnant women.…”

Venous thromboembolism prophylaxis in acutely ill hospitalized medical patients. A retrospective multicenter study

“…As VTE prophylaxis is only 50-58% effective [16][17][18] in reducing symptomatic cases, the higher the degree of prophylaxis compliance, the more likely it is that symptomatic episodes will be attributed to prophylaxis failure [19]. It should be noted that nearly half of the episodes occurred during the first 5 days of prophylaxis and asymptomatic VTE might have been present before LMWH or fondaparinux was started [20].…”

Impact of risk factors on the timing of first postpartum venous thromboembolism: a population-based cohort study from England

“…We used those estimates to calculate the number needed to treat (NNT) to prevent 1 VTE assuming that thromboprophylaxis reduces the VTE risk by 50% based on the randomized trials of general medical patients. 24 We also calculated the NNT based on the 88% risk reduction observed among nonrandomized pregnant women. 25 For our sensitivity analysis, we reran all models, excluding the small proportion (7%) of VTE events first recorded in HES because they occurred during the same hospital admission as the delivery or another risk factor event (eg, postpartum hemorrhage) and therefore precise temporality could not be established (ie, we could not determine whether VTE was the cause or consequence of a cesarean delivery or postpartum hemorrhage, particularly for those occurring on the same day).…”