Transfusion practice in total hip arthroplasty in Danish departments of orthopaedic surgery

INTRODUCTION: We examined the use of blood transfusion in patients undergoing total hip arthroplasty (THA) at 21 orthopaedic departments in Denmark. MATERIAL AND METHODS: Patients with primary THA (n = 21,773) between 1999 and 2006 were identified from the Danish Hip Arthroplasty Registry. Data on the use of blood transfusion was collected from the Danish Transfusion Database (DTDB). The outcome was defined as red blood cell transfusion (yes/no) within eight days of surgery. We estimated the relative risk for red blood cell transfusion (RR) and a 95% confidence interval (CI) adjusting for possible confounding factors, including patient- and surgery-related factors. The risk of blood transfusion for each department was compared with the overall risk of blood transfusion for all other departments. RESULTS: Overall, red blood cell transfusion was given to 8,198 of 21,960 patients (37%) (range: 16-64%). The adjusted RRs varied from 0.5 (95% CI, 0.4-0.7) to 1.8 (95% CI, 1.4-2.5) using all departments as reference. The coefficient of variation was 33% based on crude relative risk estimates and dropped to 31% after adjustment for patient- and surgery-related factors. CONCLUSIONS: Substantial differences in the use of red blood cell transfusion among THA patients were found when comparing a sample of Danish orthopaedic departments. The differences in the use of blood transfusions could apparently not be explained by a range of patient- and surgery-related factors, which suggests that the variation did not reflect differences in the patients' need for blood transfusion, but rather true differences in transfusion practice.