MO573CNI AND MTORI-BASED REGIMENS ON FIVE-YEAR COURSE OF BONE MINERAL DENSITY SCORES AFTER RENAL TRANSPLANTATION

Abstract

Abstract Background and Aims Since glucocorticoids are used in low maintenance doses today, the relationship between calcineurin inhibitors (CNI) and osteoporosis after solid organ transplantation has gained clinical significance. In contrast, (mammalian target of rapamycin inhibitors) mTORi agents are shown to have an antiresorptive effect on bone by reducing osteoclastic activity in vitro and in vivo. We investigated the bone mineral density (BMD) changes on an extremely selective group of incident renal transplant recipients under CNI or mTORi-based maintenance treatment regimens during the first five-year posttransplant course. Method This study consists of renal allograft recipients with a dialysis history of less than one year. Patients older than 50 years old, using CNI - mTORi combinations, patients with a history of a prior renal transplant, acute rejection, CNI – mTORi switch after posttransplantation first three months, bisphosphonate treatment, parathyroidectomy, diuretic use, and malignancy excluded to eliminate all confounding factors for bone mineral loss. First and fifth-year BMD scores and simultaneous laboratory parameters were evaluated. Results CNI (n=21) and mTORi (n=17) groups had similar demographics, dialysis vintages, cumulative steroid doses, first and fifth-year parathormone, calcium, phosphate, magnesium, alkaline phosphatase, and 25-OH-vitamin D levels. The femur neck scores of the CNI group decreased from -0.82(±0.96) to -1.52(±0.92) (p=0.020). We observed a significant decrease in the CNI group compared to the mTORi group [-0.70(±0.68) and 0.30(±0.36), respectively; p<0.01] when BMD score changes evaluated among years. The mean femur neck score of the mTORi group insignificantly increased from -1.13(±0.65) to -0.82(±0.56) at the fifth-year DXA scan (p=0.230). Although statistically insignificant, similar trends were also observed in L1-4 scores. Conclusion Our study suggests that CNI-based treatment is associated with decreased femur neck and L1-4 BMD scores, and mTORi-based treatment tends to be beneficial presumably due to their antiresorptive effects in the posttransplant five-year follow-up. Our findings may shed light on long-term maintenance therapy management in renal transplant patients with bone disease if supported by future studies.