TRANSFUSION PRACTICE Blood transfusion exposure in Denmark and Sweden Mads Kamper-Jørgensen, Gustaf Edgren, Klaus Rostgaard, Robert J. Biggar, Olof Nyrén, Marie Reilly, Kjell Titlestad, Agneta Shanwell, Mads Melbye, and Henrik Hjalgrim BACKGROUND: Although essential for the evaluation of blood transfusion safety, the prevalence of blood transfusion in the general population is not presently known. This study estimated the exposure to blood transfusion in the general Scandinavian population. STUDY DESIGN AND METHODS: Population-based registry data of more than 600,000 transfusion recipi- ents and general population data from 2000 to 2002 in Denmark and 1996 to 2002 in Sweden were reviewed. Outcome measures were the unit exposure rate, the 1-year period prevalence, the incidence rate, and the prevalence of exposure to blood transfusion. RESULTS: The unit exposure rate was 71.9 per 1000 population per year in Denmark and 60.9 in Sweden, corresponding to 29 percent more blood units being transfused in Denmark than in Sweden. The 1-year period prevalence was 8.8 and the incidence rate was 7.2 per 1000 population per year in Denmark, being 37 and 25 percent higher than in Sweden, respectively. The prevalences of blood transfusion in Danish males at 20, 40, 60, and 80 years of age were 1.9, 3.1, 7.6, and 18.1 percent, respectively. In Danish females, the corresponding prevalences were 1.6, 5.9, 11.1, and 20.5 percent. A similar but slightly lower prevalence was found in Sweden. CONCLUSION: Exposure to blood transfusion is fre- quent in Denmark and Sweden. At age 80 years, approximately one in five persons in the general population had received blood at least once. R isk of disease transmission via blood transfu- sion has led to comprehensive registration initiatives of blood transfusion in several coun- tries. 1,2 For example, in Scandinavia, the estab- lishment of the binational Scandinavian Donation and Transfusion (SCANDAT) database 3 has enabled studies of cancer occurrence in transfusion recipients, 4 the possibil- ity of cancer transmission, 5 the health profile of blood donors, 6 and survival of transfusion recipients. 7 Other possible benefits of transfusion registration include moni- toring and planning blood production and evaluating the possible impact of emerging or yet unrecognized trans- missible agents. 8-10 Several studies have reported the use of blood units in different countries; 11-14 however, exposure to transfused blood cannot be readily estimated from such studies since many recipients receive multiple blood transfusions. To our knowledge, such fundamental measures as the preva- lence of blood transfusion recipients in the population and the timing of their first exposure to transfusion have not been reported. Yet, this information is essential to guide discussion of the risks and benefits to be gained by modifying transfusion practices. In the present article, we ABBREVIATIONS: RR(s) = rate ratio(s); SCANDAT = Scandinavian Donation and Transfusion. From the Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark; the Department of Medical Epidemiology and Biostatistics, and the Department of Labora- tory Medicine, Karolinska Institutet, Stockholm, Sweden; and the Department of Clinical Immunology, Odense University Hospital, Odense, Denmark. Address reprint requests to: Dr Mads Kamper-Jørgensen, Statens Serum Institut, Department of Epidemiology Research, Artillerivej 5, 2300 Copenhagen S, Denmark; e-mail: mka@ ssi.dk. This study was supported by Aase and Ejnar Danielsen’s Foundation, and the creation of the SCANDAT database was supported by the National Institutes of Health. Received for publication July 29, 2008; revision received November 17, 2008; and accepted November 18, 2008. doi: 10.1111/j.1537-2995.2008.02081.x TRANSFUSION 2009;49:888-894. 888 TRANSFUSION Volume 49, May 2009