CASE-CONTROL STUDY OF RISK-FACTORS OF CREUTZFELDT-JAKOB-DISEASE IN EUROPE DURING 1993-95

Background Creutzfeldt-Jakob disease (CJD) is a transmissible spongifo rm encephalopathy. Genetic and iatrogenic forms have been recognised b ut most are sporadic and of unknown cause. We have studied risk factor s for CJD as part of the 1993-95 European Union collaborative studies of CJD in Europe. Methods The 405 patients with definite or probable C JD who took part in our study had taken part in population-based studi es done between 1993 and 1995 in Belgium, France, Germany, Italy, the Netherlands, and the UK. Data on putative risk factors from these pati ents were compared with data from 405 controls. Findings We found evid ence for familiar aggregation of CJD with dementia due to causes other than CJD (relative risk [RR] 2.26, 95% CI 1.31-3.90). No significant increased risk of CJD in relation to a history of surgery and blood tr anfusion was shown. There was no evidence for an association between t he risk of CJD and the consumption of beef, veal, lamb, cheese, or mil k. No association was found with occupational exposure to animals or l eather. The few positive findings of the study include increased risk in relation to consumption of raw meat (RR 1.63 [95% CI 1.18-2.23]) an d brain (1.68 [1.18-2.39]), frequent exposure to leather products (1.9 4 [1.13-3.33]), and exposure to fertiliser consisting of hoofs and hor ns (2.32 [138-2.91]). Additional analyses, for example stratification by country and of exposures pre-1985 and post-1985, suggest that these results should be interpreted with great caution. Interpretation With in the limits of the retrospective design of the study, our findings s uggest that genetic factors other than the known CJD mutations may pla y an important part in CJD. latrogenic transmission of disease seems r are in this large population-based sample of patients with CJD. There is little evidence for an association between the risk of CJD and eith er animal exposure, or consumption of processed bovine meat or milk pr oducts for the period studied.