Immunosuppression Regimen Use and Outcomes in Older and Younger Adult Kidney Transplant Recipients: A National Registry Analysis.

BACKGROUND Although the population of older transplant recipients has increased dramatically, there are limited data describing the impact of immunosuppression regimen choice on outcomes in this recipient group. METHODS National data for U.S. Medicare-insured adult kidney recipients (N=67,362; 2005-2016) were examined to determine early immunosuppression regimen and associations with acute rejection, death-censored graft failure and mortality using multivariable regression analysis in younger (18-64 years) and older (>65 years) adults. RESULTS The use of anti-thymocyte globulin (TMG) or alemtuzumab (ALEM) induction with triple maintenance immunosuppression (reference) was less common in older compared with younger (36.9% vs 47.0%) recipients, as was TMG/ALEM + steroid avoidance (19.2% vs 20.1%) and mTORi-based (6.7% vs 7.7%) treatments. Conversely, older patients were more likely to receive IL2-receptor antibody (IL2rAb) + triple maintenance (21.1% vs 14.7%), IL2rAb + steroid avoidance (4.1% vs 1.8%), and cyclosporine-based (8.3% vs 6.6%) immunosuppression. Compared to older recipients treated with TMG/ALEM + triple maintenance (reference regimen), those managed with TMG/ALEM + steroid avoidance (adjusted odds ratio (aOR), 0.440.520.61) and IL2rAb + steroid-avoidance (aOR, 0.390.550.79) had lower risk of acute rejection. Older patients experienced more death censored graft failure when managed with Tac+ antimetabolite avoidance (adjusted hazard (aHR), 1.411.782.25), mTORi-based (aHR, 1.702.142.71), and cyclosporine-based (aHR, 1.411.782.25) regimens, versus the reference regimen. mTORi-based and cyclosporine-based regimens were associated with increased mortality in both older and younger patients. CONCLUSIONS Lower-intensity immunosuppression regimens (e.g. steroid-sparing) appear beneficial for older kidney transplant recipients, while mTORi and cyclosporine-based maintenance immunosuppression are associated with higher risk of adverse outcomes.