Although dual-energy X-ray absorptiometry (DXA)-measured BMD at the hip and spine is widely used to diagnose osteoporosis, 10%-20% of patients who sustain osteoporosis-related fractures are reported to have normal BMD at these sites, explains Sindhura Bandaru, MD. “Some guidelines suggest that presence of a fragility fracture is diagnostic of osteoporosis, but what constitutes a ‘fragility’ fracture has challenges,” adds Dr. Bandaru. “Many guidelines recommend pharmacologic therapy with osteoporosis drugs for patients with fracture without need for BMD measurement, thus implying that these individuals have osteoporosis, but data documenting that osteoporosis medications reduce fracture risk in those with normal BMD as measured by DXA are very limited. Despite DXA being accepted as the gold standard for clinical osteoporosis diagnosis and treatment monitoring, it has important limitations. Therefore, my colleagues and I sought to explore whether older adults with fractures but normal DXA-measured BMD have normal bone when additional clinically available skeletal health assessments are considered.”
Dr. Bandaru and colleagues reviewed data on 387 patients who underwent spine and hip DXA, 8.3% of whom had normal spine/hip BMD reported. In this subset, clinically available bone data—including 0.3 and ultradistal radius T-scores, trochanteric T-scores, lumbar spine trabecular bone score, L1 opportunistic CT Hounsfield units (HU), and femoral cortical index—were assessed. Two or more of these additional bone studies were available in 28 of 32 patients, among whom approximately 80% were identified to have abnormal values at two or more sites. “Among all the skeletal assessments considered, the highest yield of identifying abnormal bone was with the opportunistic CT L1 HU and radius (0.3 and UD) DXA T scores, which were about 80% and 86%, respectively,” adds Dr. Bandaru. Among all participants, only 1.3% could not be identified as having abnormal bone using data available in the EMR.
“Our study findings demonstrate that patients with normal spine and hip BMD who sustain fracture rarely have normal bone when all the available data are considered,” Dr. Bandaru notes. “These data indirectly support the recommendations that postmenopausal women and men age 50 and older with a hip or vertebral fracture should receive osteoporosis medication, as their bone is rarely normal.”