Background: Graft and patient survival following kidney transplant are improving. However, the drivers of this trend are unclear. To gain further insight, we set out to examine concurrent changes in pretransplant patient complexity, posttransplant survival, and cause-specific hospitalization.
Methods: We identified 101 332 Medicare-insured patients who underwent their first kidney transplant in the United States between the years 1998 and 2014. We analyzed secular trends in (1) posttransplant patient and graft survival and (2) posttransplant hospitalization for cardiovascular disease, infection, and cancer using Cox models with year of kidney transplant as the primary exposure of interest.
Results: Age, dialysis vintage, body mass index, and the prevalence of a number of baseline medical comorbidities increased during the study period. Despite these adverse changes in case mix, patient survival improved: the unadjusted and multivariable-adjusted hazard ratios (HRs) for death in 2014 (versus 1998) were 0.61 (confidence interval [CI], 0.52-0.73) and 0.46 (CI, 0.39-0.55), respectively. For graft failure excluding death with a functioning graft, the unadjusted and multivariable adjusted subdistribution HRs in 2014 versus 1998 were 0.4 (CI, 0.25-0.55) and 0.45 (CI, 0.3-0.6), respectively. There was a marked decrease in hospitalizations for cardiovascular disease following transplant between 1998 and 2011, subdistribution HR 0.51 (CI, 0.43-0.6). Hospitalization for infection remained unchanged, while cancer hospitalization increased modestly.
Conclusions: Medicare-insured patients undergoing kidney transplant became increasingly medically complex between 1998 and 2014. Despite this, both patient and graft survival improved during this period. A marked decrease in serious cardiovascular events likely contributed to this positive trend.