Impact of Diabetes Mellitus on the Association of Vascular Disease Before Transplantation With Long-term Transplant and Patient Outcomes After Kidney Transplantation: A Population Cohort Study

Background: Advances in kidney transplantation have led to considerable improvements in short-term transplant and patient outcomes, but there are few data regarding long-term transplant outcomes in patients with vascular comorbid conditions. This study examined the association of vascular disease before transplantation with transplant and patient survival after transplantation and evaluated whether this association was modified by diabetes. Study Design: All deceased donor kidney transplant recipients recorded in the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA) for 1990 to 2012. Predictor: Vascular disease burden. Outcomes: All-cause mortality and overall transplant loss. Potential interactions between diabetes and vascular disease for mortality and transplant loss were assessed using 2-way interaction terms. Results: Of 7,128 recipients with 58,120 patient-years of follow-up, 854 (12.0%) and 263 (3.7%) had vascular diseases at 1 and 2 or more sites, respectively. Overall survival for recipients without vascular disease 15 years after transplantation was 65% compared with 35% and 22% among recipients with vascular disease at 1 and 2 or more sites, respectively (P < 0.001). Compared with recipients without vascular disease, adjusted HRs for mortality and transplant loss were 1.75 (95% CI, 1.39-2.20; P < 0.001) and 1.61 (95% CI, 1.30-1.99; P < 0.001), respectively, for recipients with 2 or more vascular diseases. Among recipients without diabetes but with 2 or more vascular diseases, adjusted HRs for mortality and transplant loss were 2.10 (95% CI, 1.56-2.82; P < 0.001) and 1.84 (95% CI, 1.39-2.42; P < 0.001), respectively, compared with those without vascular disease. Similar associations were not observed for recipients with diabetes mellitus (P for interaction < 0.001). Limitations: Selection bias and unmeasured residual confounders, such as the severity/extent of comorbid conditions likely to be present. Conclusions: The impact of vascular disease on long-term outcomes was modified by the presence of diabetes, whereby excess risks for death and transplant loss are more apparent in recipients without diabetes.