Associations of pretransplant serum albumin with post-transplant outcomes in kidney transplant recipients

Abstract

The association between pretransplant serum albumin concentration and post-transplant outcomes in kidney transplant recipients is unclear. We hypothesized that in transplant-waitlisted hemodialysis patients, lower serum albumin concentrations are associated with worse post-transplant outcomes. Linking the 5-year patient data of a large dialysis organization (DaVita) to the Scientific Registry of Transplant Recipients, we identified 8961 hemodialysis patients who underwent first kidney transplantation. Mortality or graft failure and delayed graft function (DGF) risks were estimated by Cox regression (hazard ratio [HR]) and logistic regression (Odds ratio [OR]), respectively. Patients were 48 ± 13 years old and included 37% women and 27% diabetics. The higher pretransplant serum albumin was associated with lower mortality, graft failure and DGF risk even after multivariate adjustment for case-mix, malnutrition-inflammation complex and transplant related variable. Every 0.2 g/dL higher pretransplant serum albumin concentration was associated with 13% lower all-cause mortality (HR = 0.87 [95% confidence interval: 0.82-0.93]), 17% lower cardiovascular mortality (HR = 0.83[0.74-0.93]), 7% lower combined risk of death or graft failure (HR = 0.93[0.89-0.97]) and 4% lower DGF risk (OR = 0.96[0.93-0.99]). Hence, lower pretransplant serum albumin level is associated with worse post-transplant outcomes. Clinical trials to examine interventions to improve nutritional status in transplant-waitlisted hemodialysis patients and their impacts on post-transplant outcomes are indicated.

Figure 1

Hazard ratio (95% confidence intervals) of post-transplant outcomes across the entire range of the pre-transplant serum albumin level using Cox regression analyses in 8961 long-term hemodialysis transplant patients who underwent renal transplantation and who were observed over a 6-year observation period (7/2001-6/2007). Panel A: Post-transplant graft failure censored all-cause death. Panel B: Post-transplant graft failure censored cardiovascular death. Panel C: Death censored graft failure. Panel D: Combined all-cause mortality or graft failure

Figure 2

Hazard ratio (95% confidence intervals) of post-transplant graft censored all-cause death for each 0.2 g/dL higher pre-transplant albumin level in selected subgroups of hemodialysis patients who underwent renal transplantation using multivariate Cox regression analyses. Footnote: “P-value for interaction” indicates whether the association of serum albumin with mortality is significantly different between the subgroups of each demographic (age, gender, race and diabetes), hemoglobin or BMI category.

Figure 3

Odds ratios (and 95% confidence intervals) of post-transplant delayed graft function (DGF) across 5 increments of pre-transplant serum albumin using multivariate logistic regression analyses (Reference: albumin <3.77 g/dL) (p-for trend <0.001 for unadjusted and 0.03 for fully adjusted logistic regression model).

Figure 4

Odds ratios (and 95% confidence intervals) of post-transplant delayed graft function (DGF) for each 0.2 g/dL higher pre-transplant albumin level in selected subgroups of hemodialysis patients who underwent renal transplantation using multivariate logistic regression analyses. Footnote: “P-value for interaction” indicates whether the association of serum albumin with DGF is significantly different between the subgroups of each demographic (age, gender, race and diabetes), hemoglobin or BMI category.