Is ESWL Score a Good Predictor of Stone Clearance? A Comparison in Patients Undergoing ESWL With Stones of Low, Medium, and High Density

Muhammad Ahsan Rehman  Khan; Shoaib  Mithani; Wajahat  Fareed

doi:10.54112/bcsrj.v6i6.1883

Authors

Muhammad Ahsan Rehman Khan Department of Urology, The Kidney Centre, Karachi, Pakistan
Shoaib Mithani Department of Urology, The Kidney Centre, Karachi, Pakistan
Wajahat Fareed Department of Urology, The Kidney Centre, Karachi, Pakistan

DOI:

https://doi.org/10.54112/bcsrj.v6i6.1883

Keywords:

Body Mass Index, Computed Tomography, Kidney Calculi, Lithotripsy, Prognosis, Renal Stone, Treatment Outcome

Abstract

Extracorporeal shock wave lithotripsy (ESWL) remains a first-line, non-invasive treatment for renal stones. However, predicting treatment success remains a challenge. The ESWL Score was proposed as a simple predictive tool, yet its real-world validation in prospective settings remains limited. Objective: To assess the predictive capabilities of the ESWL Score in determining stone clearance following ESWL in a prospective clinical setting. Methods: A prospective observational study was conducted at The Kidney Centre, Karachi, from October 2024 to April 2025. All eligible patients undergoing ESWL for renal calculi were enrolled. Demographic data, including age, gender, height, and weight, were recorded, and body mass index (BMI) was calculated. Stone characteristics—size, location, number, and density—were assessed via non-contrast computed tomography (NCCT). The ESWL Score was calculated for each patient. Stone clearance was assessed one week post-procedure using plain X-ray KUB, with clearance defined as no visible fragments or residual fragments <4 mm. Statistical analysis was performed using IBM SPSS version 26. Logistic regression was used to evaluate the predictive value of the ESWL Score. Results: A total of 143 patients were included, with a median age of 43 years (IQR=20); 87 (60.8%) were male. Median stone size was 8.1 mm (IQR=3.9), ranging from 4.3 to 15.5 mm. Median stone density was 890 HU (IQR=366), and median BMI was 24.4 kg/m² (IQR=2.6). Most patients fell within normal or overweight BMI categories. Successful stone clearance was achieved in 112 (78.3%) patients. The most common ESWL Score was 2 (45.5%), followed by 3 (36.4%). Stone size significantly affected clearance outcomes (p<0.05), whereas BMI and stone density did not. Logistic regression analysis revealed that the ESWL Score was a significant predictor of stone clearance. Specifically, patients with an ESWL Score of 2 had 9.54 times higher odds of successful clearance (p<0.001). Conclusion: The ESWL Score is a practical and reliable tool for predicting treatment success in patients undergoing ESWL for renal stones. Its simplicity and predictive validity make it a valuable adjunct in pre-procedural planning.

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References

Watson G, Payne SR, Kunitsky K, Natchagande G, Mabedi C, Scotland KB. Stone disease in low- and middle-income countries: Could augmented reality have a role in its management? BJU Int. 2022;130(4):400–7. https://doi.org/10.1111/bju.15877

Hyams ES, Matlaga BR. Economic impact of urinary stones. Transl Androl Urol. 2014;3(3):278–83. https://doi.org/10.3978/j.issn.2223-4683.2014.07.02

Kim MM, Harvey J, Gusev A, Norton JM, Miran S, Bavendam T. A scoping review of the economic burden of non-cancerous genitourinary conditions. Urology. 2022;166:29–38. https://doi.org/10.1016/j.urology.2021.10.008

Prstojevic JK, Junuzovic D, Hasanbegovic M, Lepara Z, Selimovic M. Characteristics of calculi in the urinary tract. Mater Sociomed. 2014;26:297–302. https://doi.org/10.5455/msm.2014.26.297-302

Memon A. Epidemiology of stone disease in Pakistan. In: Talati J, Tiselius HG, Albala DM, et al., editors. Urolithiasis: basic science and clinical practice. London: Springer; 2012. p. 21–38.

Zohaib A, Siddiq A, Khalid SE, Hassan W, Saleem M, Fareed W. Music harmonizes extracorporeal shockwave lithotripsy experience by reducing anxiety and pain – A randomized control trial. Pak J Med Health Sci. 2022;16:161–3.

Zohaib A, Mohammad HA, Fareed W, Khalid S, Abdullah A. Predictors of success of extracorporeal shock wave lithotripsy based on the Hounsfield units of calculi measured by noncontrast computed tomography. J Surg Pak. 2023;28(1):3–8.

Magnuson WJ, Tomera KM, Lance RS. Hounsfield unit density accurately predicts ESWL success. Alaska Med. 2005;47(2):6–9. PMID: 16459477

Ouzaid I, Al-qahtani S, Dominique S, Hupertan V, Fernandez P, Hermieu JF, et al. A 970 Hounsfield units (HU) threshold of kidney stone density on non-contrast computed tomography (NCCT) improves patients' selection for extracorporeal shockwave lithotripsy (ESWL): evidence from a prospective study. BJU Int. 2012;110(11 Pt B):E438–42. https://doi.org/10.1111/j.1464- 410X.2012.10964.x

Lee JY, Kim JH, Kang DH, Chung DY, Lee DH, Do Jung H, et al. Stone heterogeneity index as the standard deviation of Hounsfield units: a novel predictor for shock-wave lithotripsy outcomes in ureter calculi. Sci Rep. 2016;6:23988. https://doi.org/10.1038/srep23988

Park HS, Gong MK, Yoon CY, du Moon G, Cheon J, Choi YD. Computed tomography-based novel prediction model for the outcome of shockwave lithotripsy in proximal ureteral stones. J Endourol. 2016;30(7):810–6. https://doi.org/10.1089/end.2016.0153

Bengió RG, Arribillaga L, Epelde J, Orellana S, García-Önto H, Montedoro A, et al. Predictive score of success adapted to our environment to improve the results of extracorporeal lithotripsy. Arch Esp Urol. 2016;69(7):398–404. PMID: 27617549

Rasheed Y, Nazim SM, Zakaria M, Nasir MB, Khan S. Extracorporeal shock wave lithotripsy (ESWL) outcome based on CT scan and patient parameters using ESWL score. J Coll Physicians Surg Pak. 2023;33(2):199–204. https://doi.org/10.29271/jcpsp.2023.02.199

Laksita TB, Soebadi MA, Wirjopranoto S, Hidayatullah F, Kloping YP, Rizaldi F. Local anesthetics versus systemic analgesics for reducing pain during extracorporeal shock wave lithotripsy (ESWL): A systematic review and meta-analysis. Turk J Urol. 2021;47(4):270–8. https://doi.org/10.5152/tju.2021.21143

Petrides N, Ismail S, Anjum F, Sriprasad S. How to maximize the efficacy of shockwave lithotripsy. Turk J Urol. 2020;46(Suppl. 1):S19–26. https://doi.org/10.5152/tud.2020.20441

Yamashita S, Kohjimoto Y, Iwahashi Y, Iguchi T, Nishizawa S, Kikkawa K, et al. Noncontrast computed tomography parameters for predicting shock wave lithotripsy outcome in upper urinary tract stone cases. Biomed Res Int. 2018;2018:9253952. https://doi.org/10.1155/2018/9253952

Ichiyanagi O, Fukuhara H, Kurokawa M, Izumi T, Suzuki H, Naito S, et al. Reinforcement of the triple D score with simple addition of the intrarenal location for the prediction of the stone-free rate after shockwave lithotripsy for renal stones 10–20 mm in diameter. Int Urol Nephrol. 2019;51(2):239–45. https://doi.org/10.1007/s11255-018-02066-1

Yoshioka T, Ikenoue T, Hashimoto H, Otsuki H, Oeda T, Ishito N, et al. Development and validation of a prediction model for failed shockwave lithotripsy of upper urinary tract calculi using computed tomography information: the S3HoCKwave score. World J Urol. 2020;38(12):3267–73. https://doi.org/10.1007/s00345-020-03125-y

Pareek G, Armenakas NA, Panagopoulos G, Bruno JJ, Fracchia JA. Extracorporeal shock wave lithotripsy success based on body mass index and Hounsfield units. Urology. 2005;65(1):33–6. https://doi.org/10.1016/j.urology.2004.08.004

Talas H, Kilic O, Tangal S, Safak M. Does lower-pole caliceal anatomy predict stone clearance after shock wave lithotripsy for primary lower-pole nephrolithiasis? Urol Int. 2007;79(2):129–32. https://doi.org/10.1159/000106325

Yazici O, Kafkasli A, Erbin A, Bilal Hamarat M, Cubuk A, Sarilar O, et al. Effect of JJ stent on outcomes of extracorporeal shock wave lithotripsy treatment of moderate-sized renal pelvic stones: A randomized prospective study. Actas Urol Esp (Engl Ed). 2019;43(8):425–30. https://doi.org/10.1016/j.acuro.2019.03.009

Hirsch B, Abt D, Güsewell S, Langenauer J, Betschart P, Pratsinis M, et al. Outcome groups and a practical tool to predict the success of shock wave lithotripsy in the daily clinical routine. World J Urol. 2021;39(3):943–51. https://doi.org/10.1007/s00345-020-03253-5

European Association of Urology Guidelines: Urolithiasis. https://uroweb.org/guidelines/urolithiasis

Garg M, Johnson H, Lee SM, Rai BP, Somani B, Philip J. Role of Hounsfield unit in predicting outcomes of shock wave lithotripsy for renal calculi: outcomes of a systematic review. Curr Urol Rep. 2023;24(4):173–85. https://doi.org/10.1007/s11934-023-01145-w

Ullah S, Muhammad S, Farooque R, et al. The outcomes of extracorporeal shock wave lithotripsy for high-density renal stones on non-contrast computed tomography. Cureus. 2021;13(2):e13271. https://doi.org/10.7759/cureus.13271