Maximising the cost effectiveness of BMD referral for DXA using ultrasound as a selective population pre-screen.

Bone mineral density (BMD) referral for dual energy X-ray absorptiometry (DXA) is generally based upon agreed clinical referral criteria (CRC). The aim of this study was to determine whether ultrasound measurements of Broadband UI-trasound Attenuation (BUA) and velocity (VOS) provide a superior selective pre-screen referral method for BMD assessment by DXA. 107 women aged 60-69 years (64.2 +/- 2.8) had BMD measurements at lumbar spine and right femoral neck along with ultrasound BUA and VOS measurements of the left calcaneus. Each subject completed an extensive clinical and social questionnaire to ascertain those who would have met one or more of the five general clinical referral criteria adopted by our Centre. Each subject was classified by DXA using the WHO criteria as normal, osteopenic or osteoporotic at lumbar spine or femoral neck. The cost per osteoporotic subject correctly identified was calculated. As a reference, based upon DXA measurements alone on all 107 subjects, the cost per osteoporotic subject identified would be Ponds 185. If subjects had been referred using the clinical referral criteria the cost is Ponds 171. For assessment of referral by BUA or VOS, an additional charge for ultrasound measurement of all subjects was incorporated. At a BUA of 60 dB MHz-1 the cost per osteoporotic subject is Ponds 107. Ultrasound velocity or a combination of BUA or VOS with clinical referral criteria did not provide a significantly reduced cost than the current clinical referral criteria alone. This study has demonstrated that BUA provides an improved referral procedure to that currently achieved with clinical referral criteria and supports the concept of BUA being used as a selective pre-screen for DXA in 7th decade subjects.