How reliable is the ultrasound densitometer for community screening to diagnose osteoporosis in spine, femur, and forearm?

Dual X-ray absorptiometry (DXA) is the most widely used noninvasive, quanti tative diagnostic method of measuring bone density, but it exhibits several limitations for the purpose of general screening and community-based study . Thus, we evaluated the feasibility of the ultrasound densitometer SoundSc an Compact for screening the osteoporosis community. We compared the reliab ility of the SoundScan Compact's measurement to predict both osteopenia and osteoporosis at the spine, femur and forearm measured by the XR-36. World Health Organisation criteria and Korean reference were used for the diagnos is of osteopenia and osteoporosis. Of the 1827 subjects screened in the com munity, we randomly selected and invited 106 subjects to our university hos pital center for clinical epidemiology for further evaluation of their bone health using DXA. The site-specific relationships among speed of sound and bone mineral density at L2-L4 spine, femoral neck, trochanter, Ward's tria ngle, distal radius + ulna, proximal radius + ulna, and proximal radius wer e highly correlated with r values of 0.633, 0.632, 0.674, 0.632, 0.668, 0.7 8, and 0.777 respectively (all p < 0.0001). Of the 42 subjects defined as n ormal in the spine by SoundScan Compact's, 27 (64.3%) were also in agreemen t as the normal by the XR-36. However, an agreement of 43.5% (10/23) in ost eopenia and 53.7% (22/41) in osteoporosis was less sensitive. Reliability t ested by <kappa> statistics (kappa = 0.35; t = 5.3; p < 0.0001) revealed th at the degree of agreement was not coincidental. On the femur, 54.8% (23/42 ) agreed as normal, 73.9% (17/23) as osteopenia, and 39% (16/41) as osteopo rosis (<kappa> = 0.33; t = 5.5; p < 0.0001). Higher reliability was found i n the forearm, with a <kappa> Value of 0.48, t = 7.2, and p < 0.0001. A mag nitude of agreement was also greater in the forearm, with 83.3% (35/42) agr eement in normal, 52.2% (12/23) in osteopenia, and 64% (16/25) in osteoporo sis. Although the SoundScan Compact's measures different bone properties an d measurements are taken at different sites, it is a very useful instrument with a high correlation and high degree of variation and reliability to pr edict bone health at other sites :such as the spine, femur and forearm. The ultrasound densitometer such as SoundScan Compact's merits its use for com munity screening and in the primary care setting to detect osteopenia and o steoporosis for the purpose of early detection and prevention.