Correlation between the international IGA nephropathy prediction tool and IGA/C3 in patients with IGA nephropathy

Objective: In this study, we aimed to show whether there is a correlation between the International IgA Nephropathy Prediction Tool and IgA/C3, which provides important information in terms of predicting the prognosis in patients with IgA Nephropathy. Materials and Methods: The files of all patients who underwent kidney biopsy in the nephrology clinic between 01.06.2009 and 01.06.2024 were retrospectively scanned. The files of patients diagnosed with IgA Nephropathy were separated from the others. Patients diagnosed with IgA Nephropathy but thought to have secondary IgA Nephropathy were excluded from the study. The study was conducted with patients diagnosed with idiopathic IgA Nephropathy. The age, race, eGFR level, mean arterial pressure, proteinuria, presence or absence of mesangial hypercellularity, presence or absence of endocapillary proliferation, presence or absence of segmental sclerosis, presence and degree of tubular atrophy/interstitial fibrosis, RAS blocker usage status, and presence of immunosuppression were recorded for all patients at the time of diagnosis. Using these data, the 5-year progression risk was calculated with the IgA Nephropathy Prediction Tool. IgA and C3 levels obtained from serum tests performed immediately before kidney biopsy of all patients were recorded. IgA/C3 ratio was obtained by dividing serum IgA levels by C3 levels. These data were analyzed statistically. Results: The 5-year mean progression risk of the patients was calculated as 23.21±21.1. While no correlation was found between the 5-year progression risk and serum IgA and C3 levels, a positive moderate and statistically significant correlation was found between the IgA/C3 ratio and the 5-year progression risk (p= 0.012 and r= 0.503). According to the linear regression analysis results, it was determined that the IgA/C3 ratio could explain 25.3% of the change in the 5-year progression risk Conclusion: The results of the study show that there is a moderately strong and statistically significant correlation between the International IgA Nephropathy Prediction Tool and the IgA/C3 ratio. It was also determined that one-fourth of the changes in the International IgAN Prediction Tool can be explained by IgA/C3 levels. No other study was found in the literature evaluating the correlation between these two prediction tools. Based on the information obtained from our study; we think that it would be useful to develop analysis methods that combine the International IgA Nephropathy Prediction Tool and the IgA/C3 ratio in order to determine the IgAN prognosis with higher accuracy. Keywords: IgA Nephropathy, Complement, IgA/C3, International IgA Nephropathy Prediction Tool.