Risk of acquiring Creutzfeldt-Jakob disease from blood transfusions: systematic review of case-control studies.

OBJECTIVE To determine the strength of association between history of blood transfusion and development of Creutzfeldt-Jakob disease. DATA SOURCES English and non-English language articles published from January 1966 to January 1999 were retrieved using a keyword search of Medline and Embase. These were supplemented by handsearching key journals and searching bibliographies of reviews. STUDY SELECTION Two independent reviewers selected the relevant abstracts and articles. Articles were chosen that reported the results of case-control studies trying to identify rates of prior blood transfusion in patients with Creutzfeldt-Jakob disease and in controls. DATA EXTRACTION Odds ratios and information on study quality were extracted from the selected articles by two independent reviewers. DATA SYNTHESIS Five studies containing data on 2479 patients were included. Three of the five studies used medical or neurological patients as controls, the other two used population controls. Odds ratios for developing Creutzfeldt-Jakob disease from blood transfusion ranged from 0.54 to 0.89. Four of the five studies had confidence intervals that crossed 1.0. The combined odds ratio was 0.70 (95% confidence interval 0.54 to 0.89). CONCLUSIONS Case-control studies do not suggest a risk of developing Creutzfeldt-Jakob disease from blood transfusion. Rather, a trend seems to exist towards a lower frequency of previous blood transfusion in patients with Creutzfeldt-Jakob disease than in controls. However, it is important to be aware of these studies' methodological limitations-primarily the choice of control population and reliability of recall of transfusion status.