BONE LOSS IN GREAT-BRITAIN AND JAPAN - A COMPARATIVE LONGITUDINAL-STUDY

Hip fracture incidence is lower in Japan than in the West. Although di fferences have been found in peak hone mass and hip geometry between w hite and Japanese populations, these do not fully explain the differen ce in hip fracture rates. Variation in the rates of involutional bone loss may be an additional contributing factor, We address this issue i n a prospective epidemiological study comparing bone loss rate among e lderly people in Britain and Japan. Two population-based studies of bo ne loss rate in a British and a Japanese cohort were performed, Annual bone loss rates were obtained for 172 Hertfordshire men and 143 Hertf ordshire women of mean age 66 years, and a questionnaire administered to obtain information on known confounding lifestyle factors, Eighty-s ix Japanese men and 90 Japanese women of mean age 69 years completed a similar study in Taiji, Japan. British men and women were heavier tha n Japanese men and women. Differences in lifestyle were also evident; the British men were less likely to smoke and the women more likely to consume alcohol than their Japanese counterparts. The British populat ion also spent more time walking outdoors, Statistically significant d ifferences between the two populations were apparent in baseline bone mineral density at lumbar spine (p < 0.05) and trochanter (p < 0.001) in men and women with Japanese subjects having lower values, There wer e also significant differences in bone density at the femoral neck (p < 0.001) between British and Japanese males, Men gained bone at the lu mbar spine over the follow-up period in both populations. Bone loss ra tes were generally greater in the British female population than in Ja panese women: the difference was statistically significant at the femo ral neck (p < 0.05) and femoral trochanter (p < 0.001). These differen ces all remained significant after adjustment for differences in age b etween the two populations. Japanese subjects appear to have lower pea k bone mass, but slower bone loss rates in later life than their Europ ean counterparts. These differences in bone loss rate help to explain the relatively low hip fracture rates found in Japan. (C) 1998 by Else vier Science Inc. All rights reserved.