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Abstract

Abstract Title

Predicting Stone-Free Rate After RIRS Using PSA-Based Scoring Systems

Presentation Type

Podium Abstract

Manuscript Type

Clinical Research

Abstract Category *

Endourology: Urolithiasis

Author's Information

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Co-author 1

Yu-Hung Tung yuhung860606@gmail.com Kaohsiung Medical University Hospital Department of Urology Kaohsiung Taiwan *

Co-author 2

Hsiang-Ying Lee ashum1009@hotmail.com Kaohsiung Medical University Hospital Department of Urology Kaohsiung Taiwan -

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Abstract Content

Introduction

For retrograde intrarenal surgery (RIRS), several scoring systems currently exist to predict postoperative stone-free rates. We introduced a newly defined measurement method for the renal infundibulopelvic angle, called the pelvic stone angle (Figure 1), as a substitute for the angle variable in existing scoring systems. Our aim is to determine if this new angle measurement can effectively predict stone-free rates within these scoring systems after RIRS.

Materials and Methods

We retrospectively reviewed records of patients who underwent retrograde intrarenal surgery for renal stones between 2018 and 2020. Patient demographics, stone characteristics, and perioperative data were recorded. The pelvic stone angle (PSA) was used in place of the angle variable in existing scoring systems. Receiver operating characteristic (ROC) curves and area under the curve (AUC) analyses were used to compare the ability of different scoring systems to predict stone-free rates.

Results

A total of 198 patients were included in this study. Among those who underwent RIRS, the stone-free rate was 62.6% (124/198). The average stone size was 0.65 cm, the CT number was 779 HU, and the average hospital stay was 3 days. Significant differences between the stone-free and non-stone-free groups were observed in several variables, including stone burden, CT number, and scores from various scoring systems (modified Seoul National University Renal Stone Complexity [MS-ReSC], Resorlu-Unsal Stone Score [RUSS], R.I.R.S. scoring system, and T.O.HO. score), as well as multifocality. Among these scoring systems, the area under the curve (AUC) for predicting stone-free rates, ranked from highest to lowest, was as follows: T.O.HO. score (0.708), R.I.R.S. (0.652), RUSS (0.612), and MS-ReSC (0.614).

Conclusions

In conclusion, scoring systems that incorporate the PSA angle can also predict the stone-free rate after RIRS. The performance of the R.I.R.S. system was superior to RUSS and MS-ReSC, and, consistent with previous studies on the external validation of various scoring systems, the T.O.HO. score demonstrated the best predictive ability. Further studies with larger sample sizes and multicenter designs are needed to support the predictive value of PSA in scoring systems.

Keywords

RIRS, Scoring System, Pelvic Stone Angle

Figure 1

https://storage.unitedwebnetwork.com/files/1237/252283e83898810c5ac6b47a6e203ac7.jpg

Figure 1 Caption

Illustration of the pelvic stone angle ('a'), where the gray dashed line (ureteral axis with sheath) is parallel to the vertical line through the stone, making both angles "a" equal

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