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VTE and thromboprophylaxis in patients with IPD - the SPATA-DVT Study
thromboprophylaxis, particularly of low-molecular-weight-heparin in these patients is available. Here we explored the approach to thromboprophylaxis and thrombotic outcomes in IPD patients undergoing surgery at VTE-risk participating in the multicenter SPATA study. We evaluated 210 surgical procedures carried out in 155 patients with well-defined forms of IPD (VTE-risk: 31% high, 28.6% intermediate, 25.2% low, 15.2% very low). The use of thromboprophylaxis was low (23.3% of procedures), with higher prevalence in ortho- pedic and gynecological surgeries, and was related to VTE-risk. The most frequently employed thrombopro- phylaxis was mechanical and appeared to be effective, as no patients developed thrombosis, including patients belonging to the highest VTE-risk classes. Low-molecular-weight-heparin use was low (10.5%) and it did not influence the incidence of post-surgical bleeding or of antihemorrhagic prohemostatic interventions use. Two thromboembolic events were registered, both occurring after high VTE-risk procedures in patients who did not receive thromboprophylaxis (4.7%). Our findings suggest that VTE incidence is low in patients with IPD undergoing surgery at VTE-risk and that it is predicted by the Caprini score. Mechanical thromboprophylaxis may be of benefit in patients with IPD undergoing invasive procedures at VTE-risk and low-molecular-weight- heparin should be considered for major surgery.
Introduction
Venous thromboembolism (VTE) is a severe and some- times lethal complication of major surgery triggered by the release of pro-thrombotic substances from injured tis- sues, immobilization, medical comorbidities and favored by thrombophilia. It occurs in 20-25% of patients under- going general surgery and in up to 60% of patients under- going orthopedic surgery not receiving antithrombotic prophylaxis.1-4
VTE can be largely prevented by the use of mechanical and/or pharmacologic antithrombotic prophylaxis. Mechanical thromboprophylaxis with compressive stock- ings or intermittent pneumatic compression devices reduces the risk of VTE by 64% and 60%, respectively,5,6 while pharmacologic thromboprophylaxis with low molecular weight-heparin (LMWH) reduces VTE risk by 75%, although it doubles the risk of major bleeding.4,7 A meta-analysis of clinical trials comparing mechanical ver- sus pharmacologic thromboprophylaxis in general and orthopedic surgery found a 80% higher risk of deep vein thrombosis (DVT) (including asymptomatic and distal DVT) among patients treated with mechanical thrombo- prophylaxis but a 57% lower risk of major bleeding.8 Moreover, a systematic review comparing intermittent pneumatic compression with elastic compressive stock- ings in surgical patients found a prevalence of DVT of 2.9% in the first group and of 5.9% in the second.9 Recently, it has been observed that the addition of mechanical to pharmacologic thromboprophylaxis does not provide further benefit.10
The risk of VTE associated with surgery changes according to a series of variables. The American College of Chest Physicians (ACCP) evidence-based clinical practice guidelines classify surgical interventions into three VTE- risk categories depending on the type of procedure.3 Moreover, individual VTE-risk can be estimated more accurately based on patient characteristics and risk factors using appropriate scores, one of the most widely used of which is the “Caprini score” which subdivides patients into four risk categories.11
The incidence of VTE in patients with inherited platelet disorders (IPD) undergoing surgical procedures at VTE- risk is unknown, and no clinical trials or large case series have ever been reported, although several reports suggest that these patients may not be protected from thrombosis,12-15 especially when considering that some
prophylactic antihemorrhagic treatments currently used in these patients for the preparation to surgery, like platelet transfusions or recombinant factor VII a (rFVIIa),16,17 increase VTE-risk.12,18,19
Moreover, no systematic studies on the use of thrombo- prophylaxis in patients with IPD undergoing surgery have been carried out, and no information on the safety of the prophylactic administration of LMWH to IPD patients is available, although isolated reports on the safe administra- tion of anticoagulants to IPD patients have been pub- lished.20-24
Recently, the large retrospective, multicenter SPATA study evaluated bleeding complications and management of surgery in patients with IPD 17 In the present study we evaluated the approach to thromboprophylaxis adopted for the IPD patients undergoing surgery at VTE-risk partic- ipating in the SPATA study. In particular, we aimed to assess current clinical decisions on VTE prevention, to estimate postoperative VTE-risk and to evaluate the asso- ciation between the use of mechanical or pharmacologic thromboprophylaxis and clinical VTE incidence and surgi- cal bleeding in IPD.
Methods
Study population
In the current sub-study we included all the surgical procedures performed in patients enrolled in the SPATA study according to well-defined laboratory and/or molecular genetic criteria17,25-27 for whom thromboprophylaxis should have been considered accord- ing to current guidelines, including major and minor invasive inter- ventions.3,11,28 The decision to apply thromboprophylaxis was made by the attending physicians on an individual basis. Patients under 16 years of age were excluded due to the lower intrinsic VTE-risk in younger age.29,30 Surgery definitions were previously reported.17 Given the significant in situ thrombotic risk of central venous catheter insertion interventions,31 these were also consid- ered in the analysis as minor procedures with high local thrombot- ic risk.
A 48-item structured questionnaire on VTE-risk, thrombotic and bleeding events and antithrombotic prophylaxis had to be filled in for each at-risk procedure. The individual bleeding risk was estimated according to the type of IPD and previous individ- ual bleeding history as assessed by the World Health Organisation (WHO)-bleedingscore.17
The Institutional Review Board of the coordinating center
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