Outcomes of intracorporeal lithotripsy of upper tract stones is not affected by BMI and skin-to-stone distance (SSD) in obese and morbid patients

Abstract

Purpose: The purpose of this study is to determine if body mass index (BMI) and stone skin distance (SSD) affect stone free rate (SFR) in obese and morbid obese patients who underwent flexible URS for proximal ureteral or renal stones < 20 mm. Materials and Methods: A retrospective chart review was performed of consecutive patients that underwent flexible URS. Inclusion criteria were: proximal ureteral stones and renal stones less than 20 mm in the preoperative computed tomography (CT). SFR were then compared according to SSD and BMI. Results: A total of 153 patients were eligible for this analysis, 49 (32.02%) with SSD < 10 cm and 104 (67.97%) with SSD ≥ 10 cm. The mean stone size was 10.5 ± 6.4 mm. The overall SFR in our study was 82.4%. The SFR for the SSD < 10 and ≥ 10 were 79.6% and 83.7% respectively (p = 0.698) and for BMI < 30, ≥ 30 and < 40 and ≥ 40 were 82.9%, 81.7% and 90.9% respectively. Regression analysis showed no affect between BMI or SSD regarding SFR. Conclusion: Ureteroscopy should be considered as a first-line of treatment for renal/proximal stones in obese and morbid obese patients. URS may be preferable to SWL in obese patients independently of the SSD, BMI or the location of proximal stones. INTRODuCTIONThe ideal treatment for proximal ureteral and renal stones has become controversial, with the noninvasive nature of shock wave lithotripsy (SWL) and the expansion of endoscopic digital technology. The 2007 update of the EAU/AUA ureteral stone guidelines (1) showed that both ureteroscopy (URS) and SWL should be considered first-line therapy for proximal ureteral stones, as opposed to just SWL as previously reported. On the other hand SWL has emerged as the primary treatment of choice for renal calculi less than 1.5-2 cm (2).In that context, the treatment of urolithiasis in obese patients has gained more importance in the last years since obesity rates have increased markedly since 1980 in the United States (3). Data from the national Center for Health Statistics (2009Statistics ( -2010 showed that 35.7% of adults and 17% of children and adolescents in the United States were obese (4). According to the World Health Organization guidelines, a body mass index (BMI) of 18.5 to 25 kg/m 2 is considered normal, overweight is a BMI of 25 to Outcomes of intracorporeal lithotripsy of upper tract stones is not affected by BMI and skin-to-stone distance (SSD) in obese and morbid patients _______________________________________________

Predictive factors of successful extracorporeal shockwave lithotripsy (ESWL) for renal stones: evidence of retrospective study

“…Pareek et al [15] found that both BMI and HU are independent predictors for successful SEWL. However, in respect to our findings, Dede et al [13], Bulent et al [14] and Pompeo et al [16] reported in different studies that BMI does not affect SFR. Moreover, Bulent et al [14] and Pareek et al [15] found a significant relationship between the SSD and the success of ESWL.…”

Development and Internal Validation of a Classification System for Predicting Success Rates After Endoscopic Combined Intrarenal Surgery in the Modified Valdivia Position for Large Renal Stones

“…11,12 Furthermore, SSD and the Hounsfield units predict the outcomes from shock wave lithotripsy, [22][23][24] but SSD has no effect on the SF rate associated with fURS. 25 Our results suggest that SSD is not a major factor that requires the creation of appropriate access tracts and that a Swiss LithoClast pneumatic lithotripter has enough power to fragment the stones, even if the stone density is high. According to Guy's stone score, a history of spinal injury and an abnormal intrarenal anatomy are risk factors associated with PCNL outcomes.…”

Is scoring system of computed tomography based metric parameters can accurately predicts shock wave lithotripsy stone-free rates and aid in the development of treatment strategies?

“…BMI is also used as predictor, which is related indirectly to the SSD, which reflects the SW path in the body, since BMI may not directly reflect central body fat distribution, it cannot reliably used as surrogate marker for SSD, the utility of BMI in predicting successful is variable, Pareek et al .,[ 4 ] demonstrates that BMI independently predict SWL outcome, they suggest that patient with BMI >30 kg/m 2 would be suitable treated by endoscopic manipulation, Yang and colleague[ 20 ] demonstrates similar results which BMI and buttock circumference being noted as predictors of SWL failure, conversely our study corroborates with recent studies that BMI is not predictive factor for SWL outcome. [ 5 21 ]…”