[Study on the bone mineral density of elderly patients]

To analyze bone mineral density (BMD) of elderly patients in Beijing suffering from osteoporotic fracture, and discuss Chinese population BMD threshold of osteoporosis complicated by fracture.

Randomly selected three hundred male and female patients over the age of fifty years old with hip, shoulder or wrist fracture forming a research group. And randomly selected one hundred and fifty male and female patients over fifty years old with lumbar diseases forming a comparison group. Hip and spine BMD values of both groups were measured by dual energy X-ray absorptiometry and statistically analyzed by t-test; The BMD values were analyzed using a receiver operating characteristic (ROC) curve to determine the optimal cutoff point as the fracture thresholds.

BMD values relate negatively to age (research group, L2-L4 r value: -0.267, femur neck r value: -0.284, Ward triangle r value: -0.368, great trochanter r value: -0.314, all P < 0.01; comparison group, femur neck r value: -0.383, Ward triangle r value: -0.476, great trochanter r value: -0.305, all P < 0.01); There is evident difference between statistical comparisons of experimental and control group (P < 0.01); The cutoff point of the Ward triangle BMD at 0.732 g/cm(2) (91.0% sensitivity, 56.1% specificity, 9% missed diagnosis, 43.9% misdiagnosis) yields the likelihood of osteoporotic fracture for male; and it is at 0.577 g/cm(2) (72.6% sensitivity, 64.5% specificity, 27.4% missed diagnosis, 35.5% misdiagnosis) for female.

It is reasonable to take the cutoff point values as thresholds of fracture risk of osteoporosis.