Sex, age and other epidemiological characteristics of aplastic anemia patients in Japan
METHODS: An effective nationwide registration system for patients with intractable diseases including aplastic anemia has been established in Japan and is administrated by the Japanese government. We used data from the system that had been converted to electronic form between 2003 and 2010 for analysis. The data included information on patients’ age, sex, age at onset, disease type [primary (idiopathic), secondary, and other], and severity of aplastic anemia. As patients who want to receive financial assistance for treatment register with the system, the registered patients are considered to be representative of patients across Japan. Although only 70 to 80% of the data have been converted to electronic form, the data are considered to adequately represent the characteristics of all registered patients.
RESULTS: Between 2003 and 2010, approximately 9,000 patients were registered, which means that the prevalence is 7.2 per 100,000 population. Analysis of the 7,505 cases that were electronically converted in 2009 revealed the following epidemiological characteristics: the sex ratio (female/male) is 1.46; the age distribution shows two peaks in the thirties and sixties; age at onset also has two peaks at approximately ten years prior to each peak in the current age; age at onset is higher in females than males; approximately 90% of patients are primary (idiopathic) type; 50% of patients who are within one year since onset have a severe or very severe (stage 4 or 5) condition; and patients with longer suffering time have a less severe condition.
CONCLUSIONS: This report provides fundamental epidemiological information on aplastic anemia in Japan.
ACKNOWLEDGEMENTS: This study was supported by a Grant-in-Aid for Research Committee on the Idiopathic Disorders of Hematopoietic Organs from the Ministry of Health, Labour and Welfare of Japan.