Hatiboglu G et al, 2011: Prognostic variables for shockwave lithotripsy (SWL) treatment success: no impact of body mass index (BMI) using a third generation lithotripter
Hatiboglu G, Popeneciu V, Kurosch M, Huber J, Pahernik S, Pfitzenmaier J, Haferkamp A, Hohenfellner M.
Department for Urology, University of Heidelberg, Heidelberg, Germany
Study Type - Therapy (case series) Level of Evidence 4
OBJECTIVE: To investigate the effect of different variables including body mass index (BMI) on therapy outcome in patients with upper urinary tract stones treated with a third generation lithotripter, as BMI has been reported to be an independent predictor for stone-free status after extracorporeal shockwave lithotripsy (SWL) performed with first or second generation lithotripters.
PATIENTS AND METHODS: In all, 172 patients with kidney stones with a mean (range) size of 9.2 (3.0-32.0) mm were included in the study. In all, 91 patients (52.9%) were treated with a ureteric stent in situ. For SWL therapy a third generation, electromagnetic lithotripter (Siemens Lithoskop(TM) ) was used. Stone-free status was reached, when no more treatable stones were present (no stone or stone < 3 mm). BMI, stone size and localization, age, gender, treatment parameters and ureteric stent in situ were evaluated for their prognostic relevance on therapy success.
RESULTS: The mean (range) BMI of all patients was 27.8 (19.0-58.6) kg/m(2). Patients were categorized into two groups: A) patients that were stone free after one treatment; B) patients with residual stones. The mean (sd) BMI was 27.4 (4.6) kg/m(2) and 28.4 (6.1) kg/m(2) for A and B, respectively. Univariate and multivariate analysis for freedom of stones showed that only stone size (P < 0.01) and presence of a ureteric stent (P= 0.01) were independent prognostic variables. BMI had no significant influence on therapy outcome (P= 0.51).
CONCLUSION: Using a third generation lithotripter, BMI was not an independent predictor of stone-free rate after SWL therapy of kidney stones. This effect might be attributed to a greater penetration depth of the shockwave energy. Stone size and a ureteric stent in situ were the only variables with prognostic significance.
© 2010 THE AUTHORS. BJU INTERNATIONAL © 2010 BJU INTERNATIONAL.
BJU Int. 2011 Oct;108(7):1192-7. doi: 10.1111/j.1464-410X.2010.10007.x. Epub 2011 Feb 22
PMID: 21342413 [PubMed - as supplied by publisher]. FREE ARTICLE
An interesting paper that gives a realistic insight into everyday routine of ESWL and what can be expected from the first shock wave session with a third generation electromagnetic lithotripter.
The overall stone free rate including repeat ESWL or additional endourological procedures was a good 90,1 %. But the failure rates in the first session were: upper calyceal stones: 4/11, middle calyceal stones: 39,1% lower calyceal stones 49,5%, pelvis 51,4%, stone size: 3.0–5.0 mm: 36.5%, 5.1–10.0mm:78.9% , 10.0–15.0mm: 83.3%.
Multivariatanalysis did not show an impact of BMI on stone free rate. But some conclusions were that the number of patients may have been too small and that prospective, randomized studies are needed to confirm the results.