Abstract
Background
In Japan, idiopathic osteonecrosis of the femoral head (ONFH) is designated as a specified rare and intractable disease in patients for whom medical care is subsidized through the Specified Disease Treatment Research Program. Each patient is approved for the subsidy based upon a prefectural governmental review after filing an application together with a clinical research form documenting the patient's medical history, laboratory/clinical findings, and treatment. The purpose of this study was to conduct a fact-finding study of ONFH patients in the Fukuoka Prefecture based on clinical research forms of the Specified Disease Treatment Research Program.
Methods
The distribution by gender and age of ONFH patients who filed an application for subsidy under this program between 1999 and 2008 was investigated on the basis of clinical research forms in the Fukuoka Prefecture. For comparative purposes, we also investigated the distribution by gender and age of ONFH patients who had a final diagnosis of ONFH at our institution during the past three years.
Results
In the Fukuoka Prefecture, 1,244 ONFH patients (758 men, 61%; and 486 women, 39%) were identified during the 10-year period. The mean age was 48 years for men and 56 years for women. Men showed a normal age distribution with a peak in their fifties, whereas, women displayed a bimodal distribution with peaks in their fifties and seventies. The numbers of patients aged greater than 60 years were 162 (21.4%) for men and 218 (44.9%) for women. At our institution, there were 94 patients (61 men, 64.9%; and 33 women, 35.1%) who had a final diagnosis of ONFH based on radiology and pathology during the 3-year period. The mean age of these patients was 44 years for mrn and 45 years for women. Men showed a bimodal distribution with peaks in their thirties and fifties, whereas, women displayed a unimodal distribution with a peak in their fifties. The numbers of patients aged greater than 60 years were 7 (11.5%) for men and 6 (18.2%) for women. The age distribution of ONFH patients in the Fukuoka Prefecture was significantly higher, particularly for women, compared with patients at our institution.
Conclusion
The present study, based on clinical research forms showed that 1,244 patients were identified as having ONFH in the Fukuoka Prefecture during a 10-year period, with a men-to-women ratio of 6:4. For women, approximately half were aged greater than 60 years of age.
