[A population survey on bone mineral density in a fishing village in Wakayama Prefecture (Part 2); The analysis of the risk factors affecting the bone mineral density].

The purpose of this study was to detect factors affecting lumbar bone mineral density (BMD) of general inhabitants in a rural community. A cohort consisting of 2261 inhabitants aged 40-79 years was set up based on the resident registration in Taiji town, Wakayama Prefecture in 1992. Fifty men and 50 women in each of four age strata (40-49, 50-59, 60-69, 70-79), totaling 400 inhabitants, were selected randomly. After completion of a questionnaire by an interviewer, items about physical characteristics such as height, body weight, wrist length and grip power were measured. Examination of BMD of the lumbar spine and proximal femur by dual energy X-ray absorptiometry was performed. Correlation coefficients between BMDs and values of physical characteristics were determined. Lumbar BMD was examined to determine whether the following factors were positive or negative: past history, alcohol consumption, smoking habit, dietary habit, exercise, and in addition, pregnancy times and menstrual status for women. Among the values of physical characteristics, body weight was the most closely correlated with lumbar BMD. The items that showed significantly high values as factors affecting lumbar BMD were a past history of diabetes mellitus (men and women in their 70s), and exercise (men in their 50s and women in their 40s). Regarding pregnancy times and menstruation, BMD in women with a history of childbirth was significantly higher than that in those without the history among the women in their 70s. Although the BMD in the women with lactation was significantly lower than that in those without it among the women in their 40s, there was no difference in BMD between the women with and without the history who were 50 years old or over. The effect of menstrual status was investigated according to years after menopause in the women in their 50s. BMD was significantly lower in the women with ar least six years after menopause than in those within five years.