Factores predictivos de éxito tras una sesión única de litotricia extracorpórea de cálculos urinarios a las tres semanas de seguimiento / Single-Session Extracorporeal Shock Wave Lithotripsy for Urinary Calculi: Factors Predicting Success after Three Weeks of Follow-Up

Objetivo: Identificar factores predictivos de éxito después de una sesión única de litotricia extracorpórea por ondas de choque (LEOC) a las tres semanas de seguimiento. Material y métodos: Se revisaron los registros clínicos de 116 pacientes con cálculos urinarios únicos sometidos a LEOC entre octubre 2007 y agosto 2009. Las tomografías axiales computarizadas preoperatorias de todos los pacientes fueron revisadas por dos radiólogos en desconocimiento del desenlace clínico. El éxito fue definido como la desaparición completa del cálculo o la persistencia de fragmentos ≤ 2mm en la radiografía simple realizada durante las tres primeras semanas de seguimiento. El impacto de factores clínicos y radiológicos fue evaluado utilizando regresión logística. Resultados: La tasa de éxito de LEOC a las tres semanas de seguimiento fue del 49,1%. Tamaño < 8mm, área del cálculo < 30mm2, localización en el uréter distal, densidad < 1.000 UH y fragmentación intraoperatoria demostraron una significativa asociación con éxito en el análisis univariado (p<0,05). Área del cálculo<30mm2 (OR: 2,9), localización en uréter distal (OR: 3,4) y fragmentación intraoperatoria (OR: 4,2) fueron factores predictivos de éxito en el análisis multivariado (p<0,05). Conclusiones: El área del cálculo y la localización en el uréter distal son útiles en el momento de decidir acerca de la realización de una LEOC. Sin embargo, la resolución exitosa de solamente la mitad de los casos bajo los criterios evaluados recalca la relevancia de informar al paciente de la eventual necesidad de tratamientos adicionales después de una sesión única de LEOC (AU)

Introduction: The aim of this study was to identify predictive factors of success following a single-session of shock wave lithotripsy (SWL) at 3 weeks of follow-up in our center. Material and methods: The medical records of 116 patients with solitary urinary calculi who underwent single-session SWL in our department between October 2007 and August 2009 were reviewed. All preoperative unenhanced computed axial tomographies were reviewed by two radiologists blinded to clinical outcome. Success was defined as complete clearance or the persistence of fragments ≤ 2mm on a plain film at 3 weeks of follow-up. The impact of clinical and radiological factors on success was assessed by univariate and multivariate analyses. Results: The single-session SWL success rate at 3 weeks was 49.1%. Stone size <8mm, stone area < 30mm2, stone location (mid- and distal ureter), stone density <1000 HU and intraoperative fragmentation showed a significant association with SWL success in the univariate analysis (p<0.05). Stone area (OR 2.9), ureteral stone location (OR 3.4) and intraoperative fragmentation (OR 4.2) were the only predictors of success in the multivariate analysis. Conclusions: Stone area and ureteral stone location provide important information when deciding about the indication of a SWL in a patient with stone disease. However, successful resolution of only half of the cases after a single session at 3 weeks in our series undermines the relevance of informing patients about the potential need for additional treatment (AU)

[Single-session extracorporeal shock wave lithotripsy for urinary calculi: factors predicting success after three weeks of follow-up]. / Factores predictivos de éxito tras una sesión única de litotricia extracorpórea de cálculos urinarios a las tres semanas de seguimiento.

INTRODUCTION: The aim of this study was to identify predictive factors of success following a single-session of shock wave lithotripsy (SWL) at 3 weeks of follow-up in our center. MATERIAL AND METHODS: The medical records of 116 patients with solitary urinary calculi who underwent single-session SWL in our department between October 2007 and August 2009 were reviewed. All preoperative unenhanced computed axial tomographies were reviewed by two radiologists blinded to clinical outcome. Success was defined as complete clearance or the persistence of fragments ≤ 2 mm on a plain film at 3 weeks of follow-up. The impact of clinical and radiological factors on success was assessed by univariate and multivariate analyses. RESULTS: The single-session SWL success rate at 3 weeks was 49.1%. Stone size <8 mm, stone area < 30 mm(2), stone location (mid- and distal ureter), stone density <1000 HU and intraoperative fragmentation showed a significant association with SWL success in the univariate analysis (p<0.05). Stone area (OR 2.9), ureteral stone location (OR 3.4) and intraoperative fragmentation (OR 4.2) were the only predictors of success in the multivariate analysis. CONCLUSIONS: Stone area and ureteral stone location provide important information when deciding about the indication of a SWL in a patient with stone disease. However, successful resolution of only half of the cases after a single session at 3 weeks in our series undermines the relevance of informing patients about the potential need for additional treatment.