| Research Abstract |
Bone mineral density (BMD) was measured over a 10-year period in a cohort study in a mountain village in Wakayama Prefecture, Japan, to provide information on cumulative incidence of osteoporosis in the mature and elderly population and to develop an assessment system to predict incidence of osteoporosis using potential risk factors in a baseline questionnaire. Subjects comprised 400 subjects selected randomly by sex and age from a full list of residents born in 1913-1952, and BMD of the lumbar spine and proximal femur was measured using dual energy X-ray absorptiometry (DXA) at baseline and 3, 7 and 10 years. Cumulative incidence of osteoporosis over 10 years in men and women aged in their 40s to 70s was 2.0% and 15.0% at the lumbar spine, respectively, and 10.5% and 18.7% at the femoral neck, respectively. We analyzed the influence of lifestyle factors such as past history, family history, medicines, exercise, dietary habits, alcohol and smoking on cumulative incidence by logistic regression analysis after adjustment for age and gender, but did not find any significant associations. Regression formula for predicting the incidence of osteoporosis at the lumbar spine over 10 years~ was as follows : Y=exp(1.41X1-0.02X2-0.65X3-18.88X4+17.94) (X1: sex, male 0, female 1; X2: age (years), X3: weight (kg), X4: BMD (g/cm2)) R2=43.0%. Conversely, regression formula for predicting the incidence of osteoporosis at the femoral neck over 10 years as follows : Y=exp(-1.94X1+0.02X2-0.04X3-19.22X4+13.63)(X1: sex, male 0, female 1; X2: age (years); X3:weight (kg); X4: BMD (g/cm2)) R2=30.1%. Our study demonstrates that the assessment of lifestyle factors might not be sufficient to predict incidence of osteoporosis.
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