Morphometric age and survival following kidney transplantation.

BACKGROUND: As patients with chronic kidney disease become older, there is greater need to identify who will most benefit from kidney transplantation. Analytic morphomics has emerged as an objective risk assessment tool distinct from chronologic age. We hypothesize that morphometric age is a significant predictor of survival following transplantation. METHODS: A retrospective cohort of 158 kidney transplant patients from 2005 to 2014 with 1-year preoperative imaging was identified. Based on a control population comprising of trauma patients and kidney donors, morphometric age was calculated using the validated characteristics of psoas area, psoas density, and abdominal aortic calcification. The primary outcome was post-transplant survival. RESULTS: Cox regression showed morphometric age was a significant predictor of survival (hazard ratio, 1.06 per morphometric year [95% confidence interval, 1.03-1.08]; P < .001). Chronological age was not significant (hazard ratio, 1.03 per year [0.98-1.07]; P = .22). Among the chronologically oldest patients, those with younger morphometric age had greater survival rates compared to those with older morphometric age. CONCLUSIONS: Morphometric age predicts survival following kidney transplantation. Particularly for older patients, it offers improved risk stratification compared to chronologic age. Morphomics may improve the transplant selection process and provide a greater assessment of prospective survival benefits.

Using analytic morphomics to describe body composition associated with post-kidney transplantation diabetes mellitus.

BACKGROUND: Better risk assessment tools are needed to predict post-transplantation diabetes mellitus (PTDM). Using analytic morphomic measurements from computed tomography (CT) scans, we aimed to identify specific measures of body composition associated with PTDM. METHODS: We retrospectively reviewed 99 non-diabetic kidney transplant recipients who received pre-transplant CT scans at a single institution between 1/2005 and 5/2014. Analytic morphomic techniques were used to measure abdominal adiposity, abdominal size, and psoas muscle area and density, standardized by gender. We measured the associations of these morphomic factors with PTDM. RESULTS: One-year incidence of PTDM was 18%. The morphomic factors significantly associated with PTDM included visceral fat area (OR=1.84 per standard deviation increase, P=.020), body depth (OR=1.79, P=.035), and total body area (OR=1.67, P=.049). Clinical factors significantly associated with PTDM included African American race (OR=3.01, P=.044), hypertension (OR=2.97, P=.041), and dialysis vintage (OR=1.24 per year on dialysis, P=.048). Body mass index was not associated with PTDM (OR=1.05, P=.188). On multivariate modeling, visceral fat area was an independent predictor of PTDM (OR=1.91, P=.035). CONCLUSIONS: Analytic morphomics can identify pre-transplant measurements of body composition that are predictive of PTDM in kidney transplant recipients. Pre-transplant imaging contains a wealth of underutilized data that may inform PTDM prevention strategies.

Outcome differences between young children and adolescents undergoing kidney transplantation.

BACKGROUND/PURPOSE: Although graft loss remains the biggest challenge for all pediatric kidney transplant (KT) recipients, unique challenges exist within different age groups. We aim to evaluate the different characteristics and graft survival outcomes of young children and adolescents undergoing KT. METHODS: Children who underwent isolated KT between 2000 and 2013 at our institution were included in this retrospective analysis. Patient characteristics and outcomes were compared using student's t-test, chi-square test, Kaplan-Meier curve and Cox proportional hazards model. RESULTS: Of 73 children who underwent KT, 31 were <12 (young children), and 42 were ≥ 12 years old (adolescents). Overall patient survival was 100%. The younger group had superior 5-year (100% vs. 75.5%) and 10-year (94.4% vs. 43.8%) graft survival (p=0.008). Factors predictive of poor graft survival on multivariate analysis were older age at transplantation (HR 1.2, CI 1-1.4, p=0.047), female gender (HR 9.0, CI 1.9-43, p=0.006), and acute rejection episodes (HR 13, CI 2-90, p=0.008). The most common causes of graft loss were acute and chronic rejection episodes and immunosuppression nonadherence. CONCLUSION: Adolescents undergoing KT have inferior graft survival compared to younger children. In adjusted modeling, children with older age, female gender, and acute rejection episodes have inferior graft survival.

Fever, infection, and rejection after kidney transplant failure.

BACKGROUND: Patients returning to dialysis therapy after renal transplant failure have high morbidity and retransplant rates. After observing frequent hospitalizations with fever after failure, it was hypothesized that maintaining immunosuppression for the failed allograft increases the risk of infection, while weaning immunosuppression can lead to symptomatic rejection mimicking infection. METHODS: One hundred eighty-six patients with failed kidney transplants were analyzed for rates of hospitalization with fever within 6 months of allograft failure. Patients were stratified by the presence of full immunosuppression versus minimal (low-dose prednisone) or no immunosuppression, before hospital admission. Subsequent rates of documented infection and nephrectomy, as well as patient survival, were ascertained. RESULTS: Hospitalization with fever within 6 months of allograft failure was common, occurring in 44% of patients overall. However, among febrile hospitalized patients who had been weaned off of immunosuppression before admission, only 38% had documented infection. In contrast, 88% of patients maintained on immunosuppression had documented infection (P<0.001). In both groups, dialysis catheter-related infections were the most common infection source. Allograft nephrectomy was performed in 81% of hospitalized patients with no infection, compared to 30% of patients with documented infection (P<0.001). Mortality risk was significantly higher in patients with concurrent pancreas transplants or who were hospitalized with documented infection. CONCLUSIONS: Maintenance immunosuppression after kidney allograft failure was associated with a greater incidence of infection, while weaning of immunosuppression commonly resulted in symptomatic rejection with fever mimicking infection on presentation. Management of the failed allograft should include planning to avoid both infection and sensitizing events.