Faculty Bibliography

In the setting of disparities in access to simultaneous pancreas and kidney transplantation (SPKT), Medicare coverage for this procedure was initiated July 1999. The impact of this change has not yet been studied. A national cohort of 22 190 type 1 diabetic candidates aged 18-55 for kidney transplantation (KT) alone or SPKT was analyzed. Before Medicare coverage, 57% of Caucasian, 36% of African American and 38% of Hispanic type 1 diabetics were registered for SPKT versus KT alone. After Medicare coverage, these proportions increased to 68%, 45% and 43%, respectively. The overall increase in SPKT registration rate was 27% (95% CI 1.16-1.38). As expected, the increase was more substantial in patients with Medicare primary insurance than those with private insurance (Relative Rate 1.18, 95% CI 1.09-1.28). However, racial disparities were unaffected by this policy change (African American vs. Caucasian: 0.97, 95% CI 0.87-1.09; Hispanic vs. Caucasian: 0.94, 95% CI 0.78-1.05). Even after Medicare coverage, African Americans and Hispanics had almost 30% lower SPKT registration rates than their Caucasian counterparts (95% CI 0.66-0.79 and 0.59-0.80, respectively). Medicare coverage for SPKT succeeded in increasing access for patients with Medicare, but did not affect the substantial racial disparities in access to this procedure.

Identification of factors responsible for an increase in the breadth or strength of HLA-specific antibody (HSA) is critical to the continued successful management and transplantation of sensitized patients. A retrospective review of our HLA registry identified 107 patients with known HSA and sufficient information in their electronic patient record to determine the presence or absence of a proinflammatory event. The patients were stratified according to transplant status [sensitized and on the transplant waitlist (n = 65); immunosuppressed recipients of a positive crossmatch (+XM) transplant (n = 42)]. Eighty-three percent of waitlist candidates and 55% of sensitized kidney transplant recipients with a documented proinflammatory event had an associated increase in HSA. Interestingly, among patients with a culture-proven infection, 97% of the waitlist patients and 54.8% of +XM recipients had an associated rise in HSA. Overall, proinflammatory events were associated with a greater increase among waitlist patients than +XM recipients, 5.3-fold [IRR 5.25, (95% CI 4.03-6.85), p < 0.001] versus 2.5-fold [IRR 2.54, (95% CI 1.64-3.95), p < 0.001] increase in HSA. Therefore, sensitized patients known to have an infection or undergoing surgery should be monitored for expansion of HSA.

We reviewed 116 surveillance biopsies obtained approximately 1, 3, 6 and 12 months posttransplantation from 50 +XM live donor kidney transplant recipients to determine the frequency of subclinical cell-mediated rejection (CMR) and antibody-mediated rejection (AMR). Subclinical CMR was present in 39.7% of the biopsies at 1 month and >20% at all other time points. The presence of diffuse C4d on biopsies obtained at each time interval ranged from 20 to 30%. In every case, where histological and immunohistological findings were diagnostic for AMR, donor-specific antibody was found in the blood, challenging the long-held belief that low-level antibody could evade detection due to absorption on the graft. Among clinical factors, only recipient age was associated with subclinical CMR. Clinical factors associated with subclinical AMR were recipient age, positive cytotoxic crossmatch prior to desensitization and two mismatches of HLA DR 51, 52 and 53 alleles. Surveillance biopsies during the first year post-transplantation for these high-risk patients uncover clinically occult processes and phenotypes, which without intervention diminish allograft survival and function.