Ethnicity and environment may affect the phenotype of immune thrombocytopenic purpura in children.

Little is known about the influence of environmental and ethnic factors on the epidemiology of immune thrombocytopenic purpura (ITP). Therefore we compared the initial presentation and condition after 6 mo in 90 Vietnamese and 89 German and Swiss children with newly diagnosed ITP. Data from the two cohorts were collected within the same time period. No differences in age and sex were observed between the Asian and European cohorts, but significant differences between initial platelet count, the occurrence of dry versus wet bleeding symptoms, and infection preceding the onset of ITP were found. Children who had chronic ITP also differed with respect to platelet count and postinfectious state, but not initial bleeding type. In addition, chronic ITP occurred more often than expected with a male to female ratio of 1.2 in Vietnam and 2 in Germany and Switzerland. The data support the potential influence of environmental or ethnic factors on the different aspects of ITP, and point to the need for further epidemiologic investigations.