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Evaluation of possible predictive variables for the outcome of shock wave lithotripsy of renal stones.

Park YI, Yu JH, Sung LH, Noh CH, Chung JY - Korean J Urol (2010)

Bottom Line: Seventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones.In the reduced model, stone density and size were significant predictors for the outcome of SWL.The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Inje University College of Medicine, Seoul, Korea.

ABSTRACT

Purpose: The aim of this study was to evaluate possible predictive variables for the outcome of shock wave lithotripsy (SWL) of renal stones in a single center.

Materials and methods: Between March 2008 and March 2010, a retrospective review was performed of 115 patients who underwent SWL for solitary renal stones. The patients' characteristics and stone size, location, skin-to-stone distance (SSD), and Hounsfield units (HU) of stone were reviewed. The impact of the possible predictors on the disintegration of the stones was evaluated by logistic regression analysis. Receiver operator characteristic (ROC) curves were generated to compare the predictive powers of the variables.

Results: Seventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones. Significant differences were found in the mean size and mean HU of the stones (size: 8.34±3.58 mm vs. 13.57±5.41 mm, p<0.001; HU: 675.29±254.34 vs. 1,075.00±290.41, p<0.001). In the unadjusted model, age, stone size, and stone density were significant predictors. In the reduced model, stone density and size were significant predictors for the outcome of SWL. The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).

Conclusions: Stone density and size were significant predictors of the outcome of SWL for renal stones less than 2.0 cm in diameter. We should consider HU and stone size when making decisions on the treatment of renal stones.

No MeSH data available.


Related in: MedlinePlus

Measurement of the skin-to-stone distance at 0°, 45°, and 90° on an axial scan of NCCT. NCCT: non-contrast computed tomography.
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Figure 2: Measurement of the skin-to-stone distance at 0°, 45°, and 90° on an axial scan of NCCT. NCCT: non-contrast computed tomography.

Mentions: Multiple variables including patient characteristics such as sex and age and calculus characteristics such as location, size, density, and SSD were collected. Stone location was categorized as lower calyx and non lower calyx. For the measurement of stone density, three regions of interest with a diameter of 2 mm were drawn on the stone at an axial plane of the NCCT where the stone length was the longest. The mean number of HU calculated from the 3 regions represented the density of the stone on NCCT (Fig. 1). [6]. The SSD was calculated by measuring three distances from the stone to the skin at 0°, 45°, and 90° by using radiographic calipers, and the average of these three values was calculated to represent the SSD for each stone as described in the literature (Fig. 2) [6].


Evaluation of possible predictive variables for the outcome of shock wave lithotripsy of renal stones.

Park YI, Yu JH, Sung LH, Noh CH, Chung JY - Korean J Urol (2010)

Measurement of the skin-to-stone distance at 0°, 45°, and 90° on an axial scan of NCCT. NCCT: non-contrast computed tomography.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2963786&req=5

Figure 2: Measurement of the skin-to-stone distance at 0°, 45°, and 90° on an axial scan of NCCT. NCCT: non-contrast computed tomography.
Mentions: Multiple variables including patient characteristics such as sex and age and calculus characteristics such as location, size, density, and SSD were collected. Stone location was categorized as lower calyx and non lower calyx. For the measurement of stone density, three regions of interest with a diameter of 2 mm were drawn on the stone at an axial plane of the NCCT where the stone length was the longest. The mean number of HU calculated from the 3 regions represented the density of the stone on NCCT (Fig. 1). [6]. The SSD was calculated by measuring three distances from the stone to the skin at 0°, 45°, and 90° by using radiographic calipers, and the average of these three values was calculated to represent the SSD for each stone as described in the literature (Fig. 2) [6].

Bottom Line: Seventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones.In the reduced model, stone density and size were significant predictors for the outcome of SWL.The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Inje University College of Medicine, Seoul, Korea.

ABSTRACT

Purpose: The aim of this study was to evaluate possible predictive variables for the outcome of shock wave lithotripsy (SWL) of renal stones in a single center.

Materials and methods: Between March 2008 and March 2010, a retrospective review was performed of 115 patients who underwent SWL for solitary renal stones. The patients' characteristics and stone size, location, skin-to-stone distance (SSD), and Hounsfield units (HU) of stone were reviewed. The impact of the possible predictors on the disintegration of the stones was evaluated by logistic regression analysis. Receiver operator characteristic (ROC) curves were generated to compare the predictive powers of the variables.

Results: Seventy-nine patients (68.7%) had successful outcomes, whereas 36 patients (31.3%) had residual stones. Significant differences were found in the mean size and mean HU of the stones (size: 8.34±3.58 mm vs. 13.57±5.41 mm, p<0.001; HU: 675.29±254.34 vs. 1,075.00±290.41, p<0.001). In the unadjusted model, age, stone size, and stone density were significant predictors. In the reduced model, stone density and size were significant predictors for the outcome of SWL. The area under the ROC curve (AUC) was significantly higher for stone density and size than for the other parameters, but the AUC between stone density and size did not differ significantly (stone density: 0.874, stone size: 0.827, p=0.388).

Conclusions: Stone density and size were significant predictors of the outcome of SWL for renal stones less than 2.0 cm in diameter. We should consider HU and stone size when making decisions on the treatment of renal stones.

No MeSH data available.


Related in: MedlinePlus