Serologic and Histologic Predictors of Long-Term Renal Outcome in Biopsy-Confirmed IgA Nephropathy (Haas Classification): An Observational Study

Background and objective: The Haas classification of IgA nephropathy should be validated for Asian populations. More detailed and newer predictions regarding renal outcome of IgA nephropathy remains mandatory. Materials: We conducted a retrospective cohort study between January 2003 and December 2013. Clinical, Pathological, and laboratory data were all collected via available medical records. A Mann–Whitney U test was used for continuous variables and the Chi-square test was implemented for categorical variables. A Kaplan–Meier curve was put in place in order to determine patient survival and renal survival. The Youden index and Cox proportional hazard regression were used to investigate the possible factors for renal survival and predictive power. Results: All 272 renal biopsy-confirmed IgAN patients were enrolled for further studies. The univariate analysis showed that risk factors for poor renal outcome included stage 4–5 of Haas classification (HR = 3.67, p < 0.001), a poor baseline renal function (HR = 1.02 and p < 0.001 for higher BUN; HR = 1.14 and p < 0.001 for higher serum creatinine; HR = 0.95, p < 0.001 for higher eGFR), IgG ≤ 907 (HR = 2.29, p = 0.003), C3 ≤ 79.7 (HR = 2.76, p = 0.002), a higher C4 (HR = 1.02, p = 0.026), neutrophil-to-lymphocyte ratio > 2.75 (HR = 2.92, p < 0.001), and a platelet-to-lymphocyte ratio ≥ 16.06 (HR = 2.02, p = 0.012). A routine-checked markers, such as neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio, in order to predict the renal outcome, is recommended. Conclusions: This is the first study to demonstrate that Haas classification is also useful for establishing predictive values in Asian groups. A lower serum IgG (≤907 mg/dL) and serum C3 (≤79.7 mg/dL) were both risk factors for poor renal outcome. Additionally, this is the first study to reveal that serum C4 levels, an NLR > 2.75 and a PLR > 16.06, S could suggest poor renal outcome.