Post-Transplant Glomerulonephritis
Post-transplant glomerulonephritis (GMNPTR) is considered the third cause of graft loss. Retrospective cohort study of 12-year kidney transplant recipients (KT) with active follow-up and biopsy-proven diagnosis of GMNPTR. The objectives were to describe the incidence of GMNPTR, describe the frequency of histological diagnoses, and perform a comparative analysis of outcomes with 1: 1 matched controls by: gender, age ± 3 years, shared haplotypes, and year of RT ± 3 years. Kaplan–Meier was used for the analysis of time-dependent variables and Mann–Whitney U was used for comparison of graft function.

In the study period, 632 TR were performed, 54 cases of GMNPTR were found for an incidence of 8.5%. Of these 44 (81.5%) correspond to primary nephropathies, the most frequent being the mesangioproliferative pattern (n = 14, 25.9%), IgA nephropathy (n = 10, 18.5%), focal and segmental glomerulosclerosis (n = 7,12.9%); 10 cases of secondary GMNPTR were reported, of which the most frequent were: diabetic nephropathy and lupus nephritis, in 9.3% and 7.4% respectively. Of the total cases, 4 (7.4%) correspond to true recurrence, 4 (7.4%) to de novo disease and 46 (85%) to graft glomerulonephritis with unknown primary disease. The median time for the diagnosis of GMNPTR was 10 months (IQR: 3–14), the eGFR by CKD-EPI was 67.4 (± 21.2) mL/min/1.73 m2 and proteinuria 231 mg/24 h (IQR: 100–600 mg/day). Fifty-four controls were selected with the previously described matching criteria: age at the time of RT was 38.6 (± 12) years, female gender was 57.4% and the median time on dialysis was 45 months (IQR: 35–61), similar between both groups. The haplotypes shared with the donor were: 0 (n = 33, 61%), 1 (n = 13, 24%), 2 (n = 8, 15%) and 0 (n = 32, 59%), 1 (n = 14, 26%), 2 (n = 8, 15%) for cases and controls, respectively, P = NS. Renal transplantation from a deceased donor was 41% for both groups; the median follow-up for the cases was 43 months (IQR: 24–90) and for the controls 53.5 (IQR: 33–85), P = 0.5. An overall incidence of rejection of 31.8% was observed at a median of 140 months (95% CI: 28–252), log-rank P = 0.27, it was striking that the median time for the appearance of cellular rejection showed a tendency to be higher in the cases of GMNPTR (168 versus 123 months), log-rank P = 0.08; the overall incidence of graft loss was 7.5% at a median follow-up of 149 months (95% CI: 130.5–168.3) log-rank P = 0.91. Finally, when comparing eGFR by CKD-EPI in the last follow-up, no difference was observed (eGFR 64.6 ± 26 versus 60.9 ± 27 mL/min/1.73 m2 P = 0.4).

In this study the incidence of GMNPTR is similar to that reported in other cohorts, the most frequent were the primary ones and those with a mesangioproliferative pattern; After adjusting for immune risk factors, GMNPTR did not affect survival compared to a homogeneous immune risk population. On the contrary, and as is well known, the presence of rejection was associated with lower graft function. Maintenance with triple therapy could modulate the severity of GMNPTR, and therefore we see histological diagnoses of little clinical impact.