Background: Studies have demonstrated the superiority of distal forearm bone mineral density (BMD) measurement over axial BMD measurement for prediction of osteoporotic fractures of distal radius. However, distal forearm BMD measurement is not routinely performed at most centers.

Objective: To demonstrate the prevalence of discordance in diagnosis of osteoporosis using axial and distal forearm BMD measurement, and to assess whether age and other potential risk factors can predict major discordance.

Materials and Methods: Postmenopausal women aged 45 years or older and men aged 50 years or older who underwent lumbar spine, hip, and distal forearm BMD measurement at Prompt Health Center, Faculty of Associated Medical Sciences, Chiang Mai University, Thailand, between January 2021 and December 2021 were recruited. The T-scores of axial site and distal forearm were categorized based on World Health Organization classification to determine the prevalence of diagnostic discordance. Major discordance was defined as having one osteoporotic and one normal T-score. Factors potentially associated with major discordance were explored using univariate and multivariate logistic regression models.

Results: Eight hundred eighty-one participants including 621 women and 260 men with a mean age of 59.2±6.7 years were analyzed. There were 13.2% participants diagnosed with osteoporosis of the axial site, and 16.0% of the one-third (1/3) radius. The rates of major discordance, minor discordance, and concordance between axial and 1/3 radius T-scores were 3.2%, 40.5%, and 56.3%, respectively. Age of 65 years or older was significantly associated with major axial and 1/3 radius T-score discordance, with an adjusted odds ratio of 2.7 and 95% confidence interval 1.24 to 5.87 (p=0.012).

Conclusion: Diagnostic discordance is observed for at least one-third of the participants using axial and distal forearm BMD measurement. The age of 65 years or older is a risk factor for major discordance.

Keywords: Bone mineral density; Osteoporosis; Spine; Hip; Distal forearm; Discordance

DOI: 10.35755/jmedassocthai.2024.1.13936

Received 18 September 2023 | Revised 8 January 2024 | Accepted 10 January 2024