Phalangeal Densitometry Compared With Dual Energy X-ray Absorptiometry for Assessment of Bone Mineral Density in Elderly Women

Abstract

Reduced bone mineral density (BMD) is identified as a major risk factor for fracture. The World Health Organization criterion for diagnosis of osteoporosis (T-score ≤-2.5 SD) is based on dual energy X-ray absorptiometry (DXA) measurements. However DXA availability may be limited in some regions. In this study the ability of the phalangeal radiographic absorptiometry (RA) device, MetriScan, to identify women with reduced BMD at the femoral neck assessed by DXA was evaluated. The study population contained women with recent low-energy distal radius fracture and women recruited from the general population, all aged ≥50 years. A triage approach was applied in which two cut-offs for RA T-score were defined at which individuals with 90% sensitivity and 90% specificity could be identified to have or not have reduced BMD at the femoral neck defined as T-score ≤-2.5 SD. The correlation between phalangeal RA BMD and femoral neck DXA BMD was r=0.65 (p<0.001). The upper and lower RA T-score cut-off was -1.5 SD and -2.9 SD. With the triage approach being used for the whole cohort, 34% would require a central DXA assessment to determine if the femoral neck T-score is below or above -2.5 SD. The application of the RA MetriScan device can reduce the number of DXA assessments needed to detect reduced BMD. The device may thus be of clinical value if access to DXA is limited, as well as for screening purposes.