R.I.R.S. (RENAL STONE DENSITY, INFERIOR POLE STONE, RENAL INFUNDIBULAR LENGTH, STONE BURDEN) SCORING SYSTEM FOR PREDICTING STONE FREE RATE FOLLOWING RETROGRADE INTRARENAL SURGERY

Abstract

Background: This study evaluated the accuracy of the R.I.R.S scoring system (kidney stone density, inferior pole stones, stone burden, and renal infundibular length) in predicting the stone-free rate (SFR) post RIRS. Methods: This retrospective study was conducted in 50 patients aged 18-65 years undergoing RIRS for kidney stones in a tertiary institute hospital from February 2022 to June 2023. Medical records were analysed to obtain the the pre-operative investigations, intra-operative findings and post-operative complications and follow up data. The RIRS parameters were also measured to predict stone free rate post RIRS. Results: 38% patients had mild RIRS score (4-5), 60% patients had moderate RIRS score (6-8) and 2% patients had severe RIRS score (9-10). 46 patients (92%) had stone free (SF) status while remaining 4 patients (8%) had residual stone fragments. 22% patients had complications such as fever (18% patients) and urosepsis (4% patients). AUROC for stone burden (mm) and stone density (HU) predicting SF status was 0.989 (p = 0.001) and 0.837 (p = 0.028) respectively. AUROC) for R.I.R.S. Score predicting Complications was 0.8 (p = 0.002) statistically significant. Conclusion: R.I.R.S. scoring system was statistically significant in assessing stone free rate and complications. The higher R.I.R.S. score was associated with more residual stone fragments, lower stone clearance and higher postop complications. Hence R.I.R.S is a reliable and accurate preoperative tool for estimating the probability of stone-free state and complications after RIRS surgery.

Keywords

• scoring system
• urolithiasis
• stone
• surgery
• postoperative complications