Venous Thromboembolism Prophylaxis after Total Hip Arthroplasty

Abstract

PURPOSE OF THE STUDY The authors compare the frequency of thromboembolic disease in the patients receiving prophylactic therapy for 10 days with that in the patients having a prolonged course of preventive treatment recommended for up to 35 days after total hip arthroplasty (THA). MATERIAL The group first evaluated comprised patients undergoing total hip replacement in 2005 and 2006 when enoxaparin was administered for 10 days after surgery. Patients with revision THA were not included. The other group included patients operated on in 2008 who received preventive treatment for 35 post-operative days either with enoxaparin for the whole time, or with enoxaparin for 10 days of hospital stay and then warfarin up to the 35th day after surgery. Patients under going revision THA and those taking other prophylactic agents were not evaluated. METHODS The evaluation of the 2005/6 group included retrospective reviews of medical records, questionnaires sent to the patients and information received from their general practitioners. The 2008 group assessment was based on the information obtained at the patient's follow-up visit at 3 months and completed with data from the questionnaires and medical notes. We focused on the records of distal or proximal deep vein thrombosis in lower extremities and of pulmonary embolism including cases with a fatal outcome. Complications associated with pharmacological prevention were also recorded. RESULTS In the 2005/6 group including 478 patients with an average age of 67.2 years, 23 (4.8 %) patients developed thrombo- embolic disease within 3 months of surgery, six patients had pulmonary embolism of which two of them died. The thromboembolic complication developed at a median of 30.5 post-operative days, i.e., after patient discharge from hospital. In the 2008 group comprising 289 patients with an average age of 63.8 years, three patients (1 %) developed thromboembolic disease within 3 months of surgery. Of them, one woman had deep vein thrombosis in relation to a high factor VIII level; and one developed pulmonary embolism with no fatal outcome. Only the minority of patients (6.9 %) continued enoxaparin therapy, the majority (93.1 %) preferred conversion to warfarin after discharge from hospital. Of the total number of 289 patients evaluated, complications associated with prophylactic treatment were recorded in 52 patients (18 %), name- ly, in 35 patients (12.1 %) it was difficult to establish the correct dosage of warfarin, in 13 patients (4.5 %) warfarin caused minor bleeding or dyspepsia and in 4 patients (1.4 %) major bleeding was recorded. DISCUSSION In our study the patients receiving a 10-day prophylactic therapy showed a slightly higher occurrence of thromboembolic disease within 3 months of THA surgery (4.8 %) than the patients reported by Eikelboom et al. (4.3 %). The results of prolonged prophylactic treatment for at least 35 days were similar, thromboembolic disease was found in 1 % of the patients. The development of thromboembolic event was recorded in our study at a median of 30.5 post-operative days, as compared with a median of 17 days in the study by Liebermann et al. In both studies, most of the thromboembolic complications developed after the patients had been discharged from hospital. The majority of patients chose warfarin for prolonged preventive treatment. There was a high complication rate (18 %) due to not finding the correct warfarin dosage or because of its overdose CONCLUSIONS Patients undergoing THA are at high risk of developing deep vein thrombosis. The risk can be markedly reduced by prolonged pharmacological ophylaxis It is recommended that the use of warfarin for this prolonged therapy should be care- fully considered, because its optimal dose is difficult to establish and its overdose may cause serious complications.