[Regional differences in prevalence of anemia found by periodic health checkups at workplaces in Japan]

Anemia-related blood examinations are included in examinations for periodic health checkups at workplaces designated by the Industrial Safety and Health Law in Japan. The aim of this study was to determine whether there were regional differences in the prevalence of anemia in workers and, if so, to investigate possible reasons for the differences. Relationships between prevalence of anemia found by periodic health checkups and some common factors related to anemia in each prefecture of Japan were investigated by ecological regression analysis using Spearman's rank correlation coefficient. There were regional differences in the prevalence of anemia in the prefectures of Japan (5.2-11.7%), and high prevalence was observed in prefectures in the northeastern district, such as Iwate, Akita and Yamagata Prefectures, and in Fukui, Shimane and Nagasaki Prefectures. Prevalence of anemia in each prefecture was significantly correlated with the prevalence of hypertension, dyslipidemia, liver dysfunction, abnormality in ECG, hyperglycemia or glucosuria at health checkups in each prefecture. Prevalence of anemia in each prefecture was significantly correlated with the percentage of patients receiving therapy for anemia in each prefecture but not with the prevalence of myoma uteri, endometriosis uteri or mortality of uterus cancer in each prefecture. There was also no significant correlation of the prevalence of anemia with the prevalence of iron-deficiency anemia or dietary iron intake in each prefecture. The prevalence of anemia in each prefecture showed significant positive correlations with the ratio of female population to total population and the ratio of female workers to total workers in each prefecture; it also showed a significant negative correlation with the ratio of the number of large-sized workplaces (300 or more workers) to the number of workplaces with 50 or more workers in each prefecture. A considerable regional difference in the prevalence of anemia was found by periodic health checkups at workplaces, and we consider that this difference is not due to regional differences in the incidence of diseases causing genital bleeding in women but to regional differences in the ratio of female workers to total workers and the status of health control at the workplace, which depends on size of the workplace.