Multiple BMD test sites assess fracture risk
Bone mineral density (BMD) of the total hip is a better predictor of most osteoporotic fractures than either the lumbar spine or particular hip components, Canadian researchers have found. However, lumbar measurements are best for targeting spinal fractures.
This study used a database of 16,505 women aged 50 years or older when they underwent baseline dual-energy x-ray absorptiometry of the spine and hip. Relationships were evaluated among BMD measurements at four sites—the spine, femoral neck, trochanter, and total hip—and the risk of fractures at the spine, hip, forearm, or proximal humerus within a mean of 3.2 years.
“Proximal femur BMD measurements outperformed lumbar spine measurements for global fracture prediction. The total hip was the best site for overall fracture assessment,” concludes William D. Leslie, MD, of the University of Manitoba in Winnipeg, and his colleagues at the Manitoba Bone Density Program. However, “the lumbar spine measurement was useful in the prediction of spine fractures alone.”
Multiple test sites often give inconsistent results, Dr. Leslie writes, so his team specifically analyzed two subgroups that “present the greatest challenge in clinical practice”: Women whose T scores were osteoporotic at one site (≤-2.5) but not at others (>-2.5) and women whose range of T scores was >2. The general findings were upheld in both groups.
Dr. Leslie and the members of his team advocate continued testing at multiple sites for a number of reasons. “Clinical trials demonstrating benefit of antiresorptive drugs relied on lumbar spine and femur neck BMD, and it is unclear how these would apply to the total hip, with its lower diagnostic sensitivity,” he writes. “These tests also allow clinical intervention before a fracture actually occurs” (Arch Intern Med. 2007;167:1641-1647).