Abstract
This single-center observational cohort study aimed to assess the potential benefits of simultaneous pancreas and kidney transplantation (SPK) in terms of mortality and kidney graft outcomes in Japanese individuals with type 1 diabetes (T1D) and end-stage kidney disease (ESKD). We first compared all-cause mortality rates between 78 SPK recipients and 108 non-transplanted individuals with T1D and ESKD. To mitigate the bias stemming from immortal time before receiving SPK, we utilized Cox regression models treating SPK as a time-dependent covariate. Next, we compared all-cause mortality rates and kidney graft loss rates between 65 SPK recipients and 58 kidney transplantation alone (KTA) recipients. Multivariate Cox hazard models and Fine and Gray competing-risk models were employed. SPK recipients experienced significantly lower all-cause mortality rates than non-transplanted individuals, even after accounting for immortal time bias (p = 0.015 by log-rank test, hazard ratio [HR] = 0.334, p = 0.025). When comparing SPK and KTA recipients, no statistically significant difference was observed in mortality rates (HR = 0.627, p = 0.588 by Cox model; HR = 0.385, p = 0.412 by Fine and Gray model) or kidney graft loss rates (HR = 0.612, p = 0.436 by Cox model; HR = 0.639, p = 0.376 by Fine and Gray model). Dysglycemia-associated mortality were observed in non-transplanted individuals and KTA recipients, but not in SPK recipients. These findings highlight the potential life-saving impact of SPK compared with intensive insulin therapy and dialysis. Additionally, this study suggests that both SPK and KTA may offer comparable outcomes. These findings have significant implications for clinical decision-making in the context of organ transplantation for individuals with T1D and ESKD.