Height loss, vertebral fractures, and the misclassification of osteoporosis

The presence of a vertebral fracture identifies a patient who has clinical osteoporosis. However, approximately 2/3 to 3/4 of VFs are asymptomatic. Vertebral Fracture Assessment is a method derived from dual-energy X-ray absorptiometry (DXA) to assess vertebral fractures. The objectives of this study were 1) to determine the association between the degree of height loss in older men and women and the risk of a vertebral fracture, and 2) to determine if the knowledge of vertebral fractures will alter the classification of osteoporosis based on bone mineral density alone.

231 men and women over the age of 65 underwent DXA scan of their spine and hip (including bone mineral density and Vertebral Fracture Assessment), measurement of their height, and a questionnaire.

We found that height loss was significantly associated with a vertebral fracture (p=0.0160). The magnitude of the association translates to a 19% increase in odds for 1/2 in. and 177% for 3 in. Although 45% had osteoporosis by either bone mineral density or fracture criteria, 30% would have been misclassified if bone mineral density criteria were used alone.

Height loss is an indicator for the presence of vertebral fractures. Bone mineral density criteria alone may misclassify older patients who have osteoporosis.