Towards validation of use of an Australian reference database for the diagnosis of osteoporosis with DXA.

Introduction: Bone densitometry in Australia uses the data from the Geelong Osteoporosis Study for conversion of bone mineral density (BMD) to T-scores to diagnose osteoporosis based on the World Health Organization (WHO) classification criteria. An underlying assumption is that the bone status of women in Geelong city is representative of the rest of Australia. The aim of this study is to compare the prevalence of normal BMD, osteopenia and osteoporosis of sample Brisbane women to Geelong, and to assess the validity of the Geelong reference database for Australia-wide application.

Methods: The subjects were recruited as part of a longitudinal assessment of age-related changes in a random sample of women from Brisbane. The sample consisted of 503 women, aged between 40 and 79 years. Each subject had BMD measured at the lumbar spine and femoral neck.

Results: Using the WHO osteoporosis classification criteria based on T-scores, and the BMD cut-offs from the Geelong Study, the prevalence of normal BMD, osteopenia and osteoporosis was determined for the following age groupings, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69 and 70-79, to match the Geelong Study for comparison. There were no systematic differences in the prevalence of normal BMD, osteopenia and osteoporosis in the Brisbane subjects compared to the Geelong Study.

Conclusion: This finding supports the use of the Geelong data as the reference for the generation of T-scores for bone densitometry assessment for osteoporosis using dual-energy X-ray absorptiometry in Australia.