Yang TK et al, 2013: Body mass index and buttock circumference are independent predictors of disintegration failure in extracorporeal shock wave lithotripsy for ureteral calculi
Yang TK, Yang HJ, Lee LM, Liao CH
Department of Surgery, Yonghe branch, Cardinal Tien Hospital, New Taipei City, Taiwan
BACKGROUND/PURPOSE: Effective stone disintegration by extracorporeal shockwave lithotripsy (ESWL) may depend on patient- and stone-related factors. We investigated predictors of disintegration failure in ESWL for a solitary ureteral calculus.
METHODS: From July 2008 to May 2010, 203 patients who underwent ESWL for a solitary ureteral calculus were enrolled. Clinical and radiologic data were collected, and factors related to ESWL failure were analyzed.
RESULTS: Fifty-two patients (25.6%) showed ESWL failure, with a mean follow-up of 41 days. Forty patients (19.7%) required retreatment, including 12 who underwent repeat ESWL and 28 who underwent curative ureteroscopy. Patients with ESWL failure had significantly higher body weight, body mass index (BMI), and buttock circumference (BC) than patients for whom ESWL was successful. Univariate analysis showed that stone burden (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.03-1.06) and BC (OR, 1.06; 95% CI, 1.01-1.11) were predictors of ESWL failure, while BMI was a potential predictor with borderline significance (OR, 1.09; 95% CI, 0.99-1.20). Multivariate analysis showed that stone burden (OR, 1.04; 95% CI, 1.03-1.06) was a significant predictor for all patients. On stratifying patients according to the level of ureteral calculi, BC was found to be an independent predictor (OR, 1.35; 95% CI, 1.02-1.80) for ESWL failure for middle/lower ureteral calculi and BMI (OR, 1.47; 95% CI, 1.13-1.91) for upper ureteral calculi.
CONCLUSION: Stone burden is the main predictor of ESWL failure for all patients with ureteral calculi. BC and BMI are independent predictors for ESWL failure for middle/lower and upper ureteral calculi, respectively.
J Formos Med Assoc. 2013 Jul;112(7):421-5. doi: 10.1016/j.jfma.2012.02.004. Epub 2012 Oct 5
PMID:23927982 [PubMed - in process]
Similar to the result in numerous previous reports the authors found that success with SWL was inversely related to the stone burden. In this study the stone shape was considered as rectangular (length x width). Not surprisingly, large BMI and large buttock circumference also contributed to less efficient disintegration. All patients with mid and distal ureteral stones were treated with shockwaves directed from the abdominal side. Nothing is, however, mentioned about the problem with intestinal gas and no information is provided on type of analgesics. All treatments were carried out with the Dornier Compact Delta II lithotripter.