The correlation between bone mineral density measured at the forearm and at the lumbar spine or femoral neck: a systematic review and meta-analysis

Background: Current guidelines for osteoporosis diagnosis do not recommend forearm dual-energy X-ray absorptiometry (DXA) as a standard tool, except in specific cases. This systematic review and meta-analysis investigates the potential correlation between forearm BMD and BMD at the lumbar and/or hip sites. Methods: The protocol was registered in PROSPERO (CRD42024568756), and the study adhered to the PRISMA guidelines. Major databases were systematically searched from their inception until August 2024 to identify studies evaluating the ability of forearm DXA scans to detect osteoporosis, particularly in comparison to central sites like the femoral neck and lumbar spine. A meta-analysis was conducted on studies that reported correlation coefficients between these measurements. Quality assessment was conducted independently by 3 reviewers following Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) criteria. Additionally, a narrative synthesis of the main findings across different patient groups was performed. Results: Thirteen studies were included. Published between 1992 and 2023, these studies involved 5941 participants. Forearm scans exhibited strong correlations with lumbar and femoral sites (pooled effect size 0.603, 95%CI 0.579–0.627 and 0.641, 95%IC 0.600–0.680, respectively) demonstrating good predictive value for central osteoporosis. Despite some result variations, forearm DXA scanning emerged as a valid method, especially when lumbar and femoral measures are challenging. Conclusions: A DXA scan of the distal forearm proves to be a valuable supplementary tool for identifying osteoporotic conditions. This could be particularly relevant in older patients, where conducting lumbar or hip scans is often challenging or not feasible.