#2734 Modified NIH activity and chronicity indices in IgA nephropathy chronicity as a predictor of renal outcomes

Le résumé fourni par la source

Abstract Background and Aims The Oxford Classification of IgA Nephropathy is currently used for pathological diagnosis of IgA nephropathy (IgAN). Despite being useful, its two-tiered parameters may underperform in assessing certain activity criteria, chronicity, and predicting the prognosis. In our study, we aimed to investigate whether the National Institutes of Health (NIH) lupus nephritis activity and chronicity indices, commonly used in the diagnosis of lupus nephritis, could be applied to IgAN, another immune complex glomerulonephritis, along with The Oxford Classification. Method We enrolled 324 patients diagnosed with IgAN among 3888 kidney biopsies performed in our hospital between November 2000 and March 2024. 212 biopsies of patients who did not attend their routine visits, 13 allograft biopsies, and 22 suboptimal biopsies were excluded from the study. A total of 76 biopsies were evaluated by two expert nephropathologists using modified NIH activity (mNIH AI) and chronicity indices (mNIH CI) as well as the activity score (mOx AS) and chronicity score (mOx CS) we defined based on The Oxford Classification of IgA nephropathy. The mOx AS included mesangial hypercellularity, endocapillary hypercellularity, crescents, while the mOx CS incorporated tubular atrophy/interstitial fibrosis, segmental glomerulosclerosis, fibrous crescents. Demographic characteristics, laboratory parameters at biopsy, history of immunosuppressive treatment, and kidney outcomes of the patients were recorded. The relationship between the aforementioned scores and the estimated glomerular filtration rate (eGFR) and proteinuria at the time of biopsy and their effects on renal survival were investigated. Results Out of 76 patients, 34 (44.7%) were female, with a mean age of 45.5 ± 13.6 years. The follow-up period was 81.8 ± 65.6 (IQR: 24.9–113.8) months. The demographic and baseline characteristics of the patients were demonstrated in Table 1. All patients received the optimal treatment in maximum tolerated doses in conjunction with the contemporary guidelines. While no patient received kidney replacement therapy (KRT) within the first year after the biopsy, during the follow-up period, 8 patients became dialysis-dependent, and 7 patients were transplanted. Although patients who were initiated on KRT had lower eGFR at the time of biopsy, there were no statistically significant differences in urinary protein excretion or the presence of hematuria (P = 0.03, P = 0.32, and P = 0.44, respectively). We did not detect any differences in mNIH AI, mOx AS and mOx CS between the KRT and non-KRT groups. However, mNIH CI was found to be higher in the KRT-receiving patients (median 4, IQR: 3–7 vs median 6, IQR: 5–7, P = 0.04). We showed a negative correlation between mNIH CI and eGFR at the time of biopsy (r = −0.53, P < 0.001). Following receiver operating characteristic (ROC) curve analysis, the optimal cut-off value was determined to be 4.5, with a sensitivity of 86.7% and a specificity of 60.7 (AUC: 0.67, 95% CI: 0.52–0.81, P = 0.05). Patients with higher (≥5) mNIH CI had lower eGFR and higher proteinuria at the time of biopsy (eGFR P < 0.001, proteinuria P = 0.003), also higher rates of the need for KRT (P = 0.003). Conclusion In IgAN patients who required KRT during follow-up, eGFR at the time of biopsy was lower and chronicity was higher, but there was no difference in terms of activity. We found a negative correlation between eGFR and chronicity at the time of biopsy. Modified NIH chronicity indices (mNIH CI) appeared to be a useful tool to predict chronicity and the need for kidney replacement therapy in patients with IgAN.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.