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Yamashita S et al, 2017: Variation Coefficient of Stone Density: A Novel Predictor of the Outcome of Extracorporeal Shockwave Lithotripsy.

Yamashita S, Kohjimoto Y, Iguchi T, Nishizawa S, Iba A, Kikkawa K, Hara I.
Department of Urology, Wakayama Medical University , Wakayama, Japan.

Abstract

OBJECTIVES: Although previous studies have indicated that stone heterogeneity can affect extracorporeal shockwave lithotripsy (SWL) outcomes, there is no established measurement of stone heterogeneity on CT imagery. We investigated whether variation coefficient of stone density (VCSD) can predict shockwave success.
MATERIALS AND METHODS: We conducted a retrospective review of 245 patients with urinary calculi who had undergone SWL. We compared the predictive powers of treatment success between VCSD and other parameters associated with CT attenuation. In addition, we performed logistic regression analysis to identify the factors contributing to treatment success. Treatment success was determined within 3 months after first treatment using noncontrast CT.
RESULTS: The treatment success rate was 47.8% (117/245 cases). From receiver operating characteristic curves for treatment success, area under curve of VCSD (0.7181) was larger than that of mean stone density (MSD) (0.6384, p = 0.09) and standard deviation of stone density (0.5412, p < 0.01). Multivariate analysis revealed that MSD (p = 0.028) and VCSD (p < 0.001) independently predicted the outcome. Categorized by stone location, VCSD was the independent significant predictor for SWL outcomes in both kidney (p = 0.047) and ureteral calculi (p < 0.001).
CONCLUSIONS: We found that VCSD can be a novel predictor of SWL success. The development of nomograms or scoring systems, including VCSD, can assist in the decision process for patients and minimize unnecessary delay in treatment of urolithiasis.

J Endourol. 2017 Feb 2. doi: 10.1089/end.2016.0719. [Epub ahead of print]

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Комментарии 1

Hans-Göran Tiselius в 07.08.2017 08:43

This is an interesting observation that might be useful for predicting the outcome of SWL. But although the results are statistically different between patients with and without success, it is obvious that there is an overlap in terms of VCSD.

In similarity with several other studies differences were recorded for a number of variables: stone volume, MSD as well as age of patients and stone location in the lower calyces (LC). To draw conclusions from several rather than only one estimate decreases the usefulness. It is for instance not clear why treatment success is less for LC-stones, when only stone disintegration is considered.

My personal speculation is that a suitable combination of the variables listed in this manuscript might enable formulation of one mathematical expression that can be used for the desired prediction.

This is an interesting observation that might be useful for predicting the outcome of SWL. But although the results are statistically different between patients with and without success, it is obvious that there is an overlap in terms of VCSD. In similarity with several other studies differences were recorded for a number of variables: stone volume, MSD as well as age of patients and stone location in the lower calyces (LC). To draw conclusions from several rather than only one estimate decreases the usefulness. It is for instance not clear why treatment success is less for LC-stones, when only stone disintegration is considered. My personal speculation is that a suitable combination of the variables listed in this manuscript might enable formulation of one mathematical expression that can be used for the desired prediction.
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