Utility of Oxford Classification in Post-Transplant Immunoglobulin A Nephropathy.

BACKGROUND: With increasing graft survival, post-transplant immunoglobulin A nephropathy (IgAN) has emerged as an important cause of chronic graft dysfunction in renal allograft recipients. We studied the clinico-pathological features of post-transplant IgAN regardless of the primary disease. The aim was to study the usefulness of the Oxford classification in predicting survival.

METHODS: Indication graft biopsy specimens (n = 915) were received during a 10-year period; 27 biopsy specimens from 22 patients were diagnosed as IgAN.

RESULTS: Post-transplant IgAN was seen in 2.6% of biopsy specimens. Mean time to occurrence was 71.6 ± 47.6 months (range, 6.8 months to 16 years), occurring most commonly 4 to 8 years after transplant. Associated rejection was present in 4 biopsies; 72.7% (16/22), 91% (20/22), and 31.8% (7/22) presented with rise in serum creatinine, proteinuria, and hematuria, respectively. Four (21%) patients had nephrotic range proteinuria. Mesangial hypercelullarity (M1), endocapillary hypercelullarity (E1), segmental glomerulosclerosis (S1), and tubulo-interstitial fibrosis (T1-2) was present in 36.6%, 22.7%, 54.5%, and 31.8% biopsies, respectively. The most frequent Haas class was III (n = 7; 29.1%), followed by classes IV and I (n = 5; 20.8% each). The 2- and 5-year graft survival rates were 75% and 56%, respectively. High serum creatinine, low estimated glomerular filtration rate, E1 and T lesions, and degree of interstitial inflammation predicted graft survival. Interestingly, percentage (>25%) of segmentally sclerosed glomeruli and not S1 correlated with graft outcome.

CONCLUSIONS: The Oxford MEST scheme is useful in predicting graft survival in post-transplant IgAN. The degree of interstitial inflammation is also an important feature for determining graft outcomes in post-transplant IgAN.