Serious Symptomatic Thromboembolic Complications in Patients Undergoing Total Hip Replacement - A Prospective Study.

Purpose: To describe the rate and time of onset of serious thromboembolic (TE) complications within the first 90 postoperative days in an unselected population of THR patients. Secondary to analyse the data base for possible risk factors of TE.

Material and method: Five hundred (430 primary THR and 70 revision THR) consecutive patients undergoing THR in Frederiksborg County, Denmark from January 2004 until May 2005 participated. The patients were interviewed the day before surgery for medical history. On the 5^th postoperative day and at a telephone interview 90 days postoperatively patients were asked about signs and symptoms of acute myocardial infarction (AMI), pulmonary embolism (PE), deep vein thrombosis (DVT), transitory cerebral ischemia (TCI)/stroke, retinal vein thrombosis (RVT) and other cardio vascular events. All events were validated in hospital and/or the general practitioners files, using international criteria. All patients except 1 had chemical thromboprophylaxis during hospitalization. No patients had extended thromboprophylaxis after discharge. 498 patients had 90 days follow-up. Two patients withdrew their consent.

Results: 24 patients (4.8%) experienced at least one serious TE complication during the first 90 days after the operation. Two (0.4%) patients died in relation to the operation (no autopsy was performed). Five patients (1.0%) had PE. One patient (0.2%) had AMI, 10 (2.0%) had DVT, two (0.4%) had RVT and four (0.8%) had TCI. Two patients experienced two events - one had AMI and later on a TCI, another had PE and TCI on the same day. Nine patients had their first event during the first five postoperative days - 15 patients had their first event after the 5th postoperative day. The only significant risk factor found in a backward logistic regression analysis including interaction (test for confounder/bias) was the length of the operation P=0.003 OR= 1.016 (1.005–1.026). This study has not been able to show any significant correlation between age, gender, co-morbidities, preoperative hemoglobin value ore platelet count, high ASA-score, kind of anesthesia, indication for operation or use of cement or interactions between the above in the logistic regression analysis, but individually all these factors were significant risk factors in the introductory bivariate analysis.

Discussion: This study shows that venous and arterial thrombotic complications persist to be a major contribution to postoperative morbidity and mortality after elective total hip replacement, despite of rigorous early mobilization and optimized regimens of prevention of thromboembolism. After this study has been performed ACCP has recommended extend prophylaxis by LMWH, pentasaccharide or warfarin up to 4–5 weeks after total hip replacement. Further research to identify patients at risk is warranted to optimize risk/benefit of total hip replacement and prevention of venous and arterial thromboembolism. The majority of events occurred after discharge calling for improvement of the post-discharge period to reduce the risk of serious thromboembolism.