Spatial Clusters of Creutzfeldt-Jakob Disease Mortality in Japan between 1995 and 2004

Abstract

Background: There is suggested to be a geographical difference in Creutzfeldt-Jakob disease (CJD) mortality in Japan. We performed a study to detect localized clusters and hot-spot areas of deaths from CJD in Japan during the 10-year period from 1995 to 2004. Methods: The diagnosis of CJD was taken from the death certificate (coded as A81.0 in the ICD-10). A total number of 1,168 CJD deaths (500 males and 668 females) were used for analysis using empirical Bayes estimates of standardized mortality ratios and the flexible spatial scan statistic to detect clusters. To detect the most likely cluster, p values were obtained using Monte Carlo hypothesis testing (with p < 0.05 as statistical significance).Results: The most likely cluster of CJD mortality was located in the northwest region from the base of Mt. Fuji, stretching over the two neighboring prefectures of Yamanashi and Shizuoka (relative risk = 2.28, p = 0.021). Some other clusters were detected but were not significant. Conclusions: The present study supports the evidence of geographical clustering of deaths from CJD at a specific location in Japan.