Incidence of thoracic vertebral fractures among adult health study participants, Hiroshima and Nagasaki, 1958-86

The incidence of thoracic vertebral fractures (TVF) in a fixed Hiroshima and Nagasaki population of 16,027 was determined by sex, age, and atomic bomb ionizing radiation exposure. Diagnosis was based on lateral chest radiographs made from 1 July 1958 to 28 February 1986. Born between 1880 and 1940, the subjects were categorized by sex into 10-year birth cohorts. When examined by birth cohort and age at onset, the age dependency of TVF incidence showed a good fit to a log-linear regression model. In females, TVF incidence tended to be lower in the younger birth cohorts and tended to increase with age in all birth cohorts. With each 10-year increase in age, the incidence among females increased by a factor of 1.7. In males, the incidence was significantly lower in the younger birth cohorts, but did not increase with age. The incidence decreased by a factor of 0.5 in males and 0.6 in females as the birth cohort age became younger. TVF incidence was greater in males until the age of 50, was equal by sex in the sixth decade, and was greater among females, who were 60 years of age or older. TVF incidence did not differ by city, and no correlation with A-bomb radiation exposure was demonstrated. (author)