The diagnostic utility of systemic immune inflammation index in differentiating crescentic glomerulonephritis subtypes

Abstract

Introduction: Hematological indices have been used as a marker for differential diagnosis or prognostic prediction of diverse diseases. Since no study has been conducted to search for the relationship between the systemic immune inflammation index (SII) and crescentic glomerulonephritis (GN), we aim to investigate the diagnostic utility of SII in crescentic GN subtypes. Methods: In this retrospective study, patients with crescentic GN were divided into three groups: type 1 crescentic GN (n=1), type 2 crescentic GN (n=44), and type 3 crescentic GN (n=44). There was only one patient in the type 1 crescentic GN group, so he was excluded. The groups were compared regarding SII, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR). The SII was calculated by platelet count × neutrophil count/lymphocyte count. The predictive ability of these indices was determined by using the receiver operating characteristic (ROC) curve analysis. Also, the correlation of the indices with inflammatory markers and renal function tests was analyzed. Results: Patients with crescentic GN type 3 had higher levels of urea, creatinine, erythrocyte sedimentation rate (ESR), SII, NLR, and PLR levels; they showed lower levels of 24-hour protein excretion rate and estimated glomerular filtration rate (eGFR) compared to crescentic GN type 2 group. According to the ROC curve, SII had the highest level of discriminating crescentic GN subtypes, and NLR was the lowest. Also, there was a significant positive correlation between SII and the percentage of crescentic glomeruli, urea, and creatinine, as well as a negative correlation between SII and eGFR. Conclusions: This study revealed that a high SII might reflect the severity of kidney injury in patients with crescentic GN. Further studies with large series are needed to confirm the above results.