VERTEBRAL FRACTURE PREVALENCE IN WOMEN IN HIROSHIMA COMPARED TO CAUCASIANS OR JAPANESE IN THE US

Background. Although vertebral fractures are very common among elderly Caucasian women, no studies have compared the prevalence to that amon g Asian populations. Any observed differences in prevalence might lead to the identification of important environmental and/or genetic facto rs, We therefore compared the prevalence of vertebral fractures among US Caucasians to native Japanese and Japanese immigrants in Hawaii usi ng a standardized approach. Methods. Spinal radiographs of women aged greater than or equal to 50 years were obtained from native Japanese i n Hiroshima, Japanese-Americans in Hawaii, and North American Caucasia ns in Minnesota between 1982 and 1991. Fractures were defined as verte bral heights >3 standard deviations (SD) below the vertebra-specific m ean. Results. Compared to Japanese-Americans, odds ratios (OR) and 95% confidence intervals (CI) for prevalent vertebral fractures were 1.8 (95% CI : 1.3-2.5) for native Japanese women and 1.5 (95% CI : 1.1-2.1 ) for Minnesota Caucasians. The OR tended to be higher when comparing the prevalence of two or more fractures per person: OR = 3.2 (95% CI : 2.0-5.3) for native Japanese and OR = 1.9 (95% CI : 1.2-3.2) for Minn esota Caucasians. Similar results were observed for native Japanese us ing a fracture definition of greater than or equal to 4 SD below the m ean, but the OR for Caucasians was reduced to 1.2 (95% CI : 0.6-2.3).C onclusion. The observation that, among these three populations, hip fr acture incidence is lowest but spine fracture prevalence is greatest a mong native Japanese suggests that different risk factors may be respo nsible.