Current clinical guidance on prevention and management of osteoporosis recommends that the diagnosis should be based on bone mineral density (BMD) measurements in the lumbar spine and the proximal femur, despite patients’ age. Given that in elderly population several degenerative processes in the spine could falsely increase lumbar spine BMD, a recent manuscript published by Frisoli Jr et al. in the October 2021 issue of Bone Reports, assessed whether the distal forearm BMD with the proximal femur BMD (DFF) has greater sensitivity for the diagnosis of osteoporosis in older adults with cardiovascular diseases, than the lumbar spine BMD with the proximal femur BMD (LSF).
This was a cross-sectional study of SARCopenia and Osteoporosis in older adults with cardiovascular diseases (SARCOS). Five hundred and fifteen (515) older adults met eligibility criteria and underwent DXA analysis of the lumbar spine, distal forearm, femoral neck, and total femur using dual-energy X-ray absorptiometry. To assess the sensitivity of the DFF vs. SPF criteria, participants were stratified into <80-year-old and >80-year-old age groups, and according to gender. These results were compared with the multiple bone sites (MS) criteria (lumbar spine, distal radius, femoral neck, and total femur BMD) for osteoporosis diagnosis.
Results showed that osteoporosis by MS criteria was diagnosed in 46.8% of the population, whereas by SPF in 34%, and by DFF in 42.2%. In particular, for every 100 individuals aged >80 years with osteoporosis diagnosed by MS criteria, SPF failed to identify it in 31, whereas only 5 individuals were not diagnosed by DFF.
Authors concluded that in their study DFF showed higher sensitivity for the diagnosis of osteoporosis, compared to the SPF criteria and suggested that distal forearm BMD in conjunction with proximal femur BMD appears to be an alternative for diagnosing osteoporosis in very old adults with cardiovascular disease. However, authors clearly mentioned that further studies with different populations are warranted to consolidate this statement.
Commentary: It should be emphasized that the recommendation of the International Society of Clinical Densitometry (ISCD https://iscd.org/learn/official-positions/adult-positions/) is to base the diagnosis of osteoporosis solely on central sites and only consider the forearm in exceptional circumstances. Hence, the gold standard in the present study being a Multi-Site assessment that includes the forearm is not universally accepted as diagnostic of osteoporosis and it is not surprising that sensitivity is higher when forearm DXA is added since forearm DXA is part of the Multi-Site construct.