Discordance in diagnosis of osteoporosis using spine and femur bone densitometry: prevalence and related factors

Introduction: This study was conducted to evaluate prevalence and risk factors for diagnostic discordance for osteoporosis due to different T-scores of lumbar spine and femoral neck. Methods: In this cross sectional study demographic, anthropometric and risk factors for osteoporosis were derived from a database on 3,039 post-menopausal women who underwent bone densitometry for the first time in our department (Kurdistan Nuclear Medicine Center) from 2003 to 2010. DXA was performed on L2-L4 vertebrae and femoral neck for all cases. Major discordance (one site osteoporotic and the other normal) and minor discordance (difference between two site no more than one WHO diagnostic class) were determined. The association of related risk factors with discordance of interest was assessed.  Results: Prevalence of osteoporosis and osteopenia in these post-menopausal women with mean age of 58.5 ±8.7 years, menopausal period of 11.2+9.4 years and mean BMI of 28+4.5 were 37.7% and 50.7%, respectively. Frequencies of minor and major discordances were 40.0% and 1.8%, respectively. Conclusion: The minor discordance was a common finding; however, the major discordance is uncommon. The most important risk factors for major discordance were age, menopausal duration and BMI. There was no significant relationship between other risk factors (smoking and history of bone fracture) and diagnostic T-score discordances.