A statistical model to determine the optimal bone mineral density (BMD) screening schedule in liver transplant recipients.

Background: The American Association for the Study of Liver Diseases (AASLD) and the American Society of Transplantation (AST) 2012 practice guidelines based on expert opinion provide surveillance frequency guidelines for dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) scans after liver transplant (LT). Since then, post-transplant immunosuppression has changed. This study aims to use statistical models to identify the optimal DXA surveillance frequency after LT. Materials and Methods: This study retrospectively evaluated 402 LT recipients followed for up to 8 years post-LT, each with at least one pre-LT and two post-LT DXA scans. Linear mixed-effects (LME) models using random slopes and intercepts were used to identify whether BMD decline was linear or non-linear (quadratic) in time. Multivariate LME models were used to model the decline in femoral neck (FN), total hip (TH), and L1-L4 BMD decline after LT adjusting for demographic and clinical variables. Results: Males had higher pre-LT BMD than females (P<0.001 at all sites). The rate of BMD loss was fastest at the FN, and faster in patients with normal pre-LT BMD than in patients with low pre-LT BMD (osteopenia/osteoporosis). The model predicted that there would be a significant FN BMD decrease in patients with normal pre-LT BMD after approximately 481 days post-LT (1 year, 3 months). Conclusion: LT recipients with normal pre-LT BMD should have DXA scans ~481 days post-LT. LT recipients with low BMD pre-LT who were more likely to be treated with bisphosphonates did not need annual DXA screening.