Determinants of bone mass in the Chinese old-old population.

One hundred and eighty-eight elderly men and women were included in a study of bone mass at the neck of femur and its related factors. The study subjects were a subsample of a Hong Kong wide study of the elderly population aged 70 years and above. The study variables included age, sex, body measurements of height, weight, body mass index, dietary calcium intake, grip strength, 16 feet (5 m) gait speed, smoking, drinking, and years since menopause among women. The neck of femur bone mineral density among elderly men was about 1 standard deviation higher than that of women. Subjects aged 85 years and above had about 20% lower bone mineral density at the neck of femur when compared with those in the age group 70-74 years. Mean dietary calcium intake ranged between 300 and 430 mg/day and was not associated with bone mass. Multiple regression analysis showed that body weight, 16 feet gait speed, sex and alcohol consumption explained 46% of the total variance of femoral neck bone mineral density. Body weight was the most significant predictor of bone mineral density, with a partial correlation coefficient of 0.5. The maintenance of body weight within the acceptable weight range and promotion of physical fitness may be important measures in reducing bone loss in the elderly population.