For the individual patient with primary IgA nephropathy (IgAN), it remains a challenge to predict accurately the long term outcome at 10 and 20 years after disease onset. We studied it in a prospective cohort of 332 (237 males, 71.4%) biopsy-proven IgAN patients, the IGAN-STET-CO, aged at diagnosis of mean = 41.4 (SD=15.1) years, with a total exposure time of mean = 12.9 (9.5) y. Using three consensual risk factors (RF) simplified as dichotomous covariates : occurrence of hypertension, proteinuria ≥1 g/d, and severe pathological lesions (global optical score ≥8), we calculated an absolute renal risk (ARR) of dialysis/death (D/D), in analogy to the absolute cardiovascular risk. The ultimate prediction according to the number of RF present at diagnosis (ARR score: 0, 1, 2, or 3) was done by the Cox regression and the Kaplan-Meier survival methods. Overall, this ARR scoring permitted significant (P<0.0001) stratification of the risk. The cumulative incidence rate of D/D events (N=45), respectively at 10 and 20y, was 2 and 4% for ARR=0 (45.5% of all cases), 2 and 9% for ARR=1 (20.8%), 7 and 18% for ARR=2 (19.6%), and 29 and 64% for ARR=3 (N=47; 14.1%) in adequately treated patients. Effective control of hypertension and reduction of proteinuria improved survival without D/D when achieved. This absolute renal risk score evaluated at diagnosis, allowed accurate prediction of ultimate dialysis/death risk and was also validated in another cohort. This is a significant progress in the management of the individual patient with lgA nephropathy
