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Shinde S et al, 2018: Factors Affecting the Outcome of Extracorporeal Shockwave Lithotripsy in Urinary Stone Treatment.

Shinde S, Al Balushi Y, Hossny M, Jose S, Al Busaidy S.
Urology Department, Armed Forces Hospital, Muscat, Oman.
Planning and Studies Department, Oman Medical Specialty Board, Muscat, Oman.
Lithotripsy Unit, Armed Forces Hospital, Muscat, Oman.

Abstract

Objectives: We sought to evaluate the factors affecting the outcome of extracorporeal shockwave lithotripsy (ESWL) in urinary stone treatment.
Methods: We conducted a retrospective review of 235 adult patients treated with ESWL, for radiopaque renal or ureteric stones between January 2015 and December 2016. Patient's age, sex, stone size, laterality, location, density, skin-to-stone distance (SSD), and presence of double J stent were studied as potential predictors. At the end of three months, the patients were divided into success and failure groups and the significance was determined.
Results: Of the 235 patients (188 males and 47 females) analyzed, ESWL was successful in 79.1%. Univariate analysis of both groups revealed no significant difference in patient's age and stone laterality. Statistically significant differences in gender, stone size, stone site, stone density, SSD, and patients with stents were observed. Statistically significant factors in multivariate logistic regression analysis were sex and stent. Females had three-times higher risk for ESWL failure than males (odds ratio (OR) = 3.213; 95% confidence interval (CI): 1.194-8.645; p = 0.021) and a higher failure rate when a stent was used (OR = 6.358; 95% CI: 2.228-18.143; p = 0.001).
Conclusions: This study revealed that ESWL can treat renal and ureteric stones successfully with an inverse association between outcome and predictors such as stone size and density, SSD, and stent presence. These factors can help us in improving patient selection and ensure better results at lower cost.

Oman Med J. 2018 May;33(3):209-217. doi: 10.5001/omj.2018.39.

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Comments 1

Hans-Göran Tiselius on Wednesday, 22 August 2018 07:53

In a retrospective analysis of SWL carried out in 235 patients, the authors have identified factors of importance for failed treatment.

The overall success rate (i.e. completely stone free urinary tract or presence of residual fragments ≤4 mm) was 79%. This result was the combined outcome in patients treated for renal as well as ureteral stones. There were 145 stones located in the ureter and 90 in the kidney. The success rates were 80% (116/145) for stones in the ureter and 78% (70/90) for stones in the kidney. The results for ureteral stones were slightly lower than expected. This might be a result of the fact that the authors used the SLX-F2 device with lower power levels than I have been used to.

Why power levels of 4 and 4.5-7 for renal and ureteral stones, respectively were not exceeded might be explained by the type of analgesia used.

One surprising observation was the significantly lower success rate in women and it is suggested by the authors that this difference can be understood by lower pain tolerance in women.

That stone density, stone size and SSD (skin-to-stone distance) are factors of importance for successful treatment is well recognized. Improved success can be expected with more efficient pain treatment and higher SW-power.

Regarding SWL of ureteral stones there is no information on how the patients were positioned in the lithotripter or how the authors dealt with stones in the mid ureter.

It should be noted, however, that the results with lower calyx stones (77%) were very similar to those of stones in other locations (79%) and that stones measuring

In a retrospective analysis of SWL carried out in 235 patients, the authors have identified factors of importance for failed treatment. The overall success rate (i.e. completely stone free urinary tract or presence of residual fragments ≤4 mm) was 79%. This result was the combined outcome in patients treated for renal as well as ureteral stones. There were 145 stones located in the ureter and 90 in the kidney. The success rates were 80% (116/145) for stones in the ureter and 78% (70/90) for stones in the kidney. The results for ureteral stones were slightly lower than expected. This might be a result of the fact that the authors used the SLX-F2 device with lower power levels than I have been used to. Why power levels of 4 and 4.5-7 for renal and ureteral stones, respectively were not exceeded might be explained by the type of analgesia used. One surprising observation was the significantly lower success rate in women and it is suggested by the authors that this difference can be understood by lower pain tolerance in women. That stone density, stone size and SSD (skin-to-stone distance) are factors of importance for successful treatment is well recognized. Improved success can be expected with more efficient pain treatment and higher SW-power. Regarding SWL of ureteral stones there is no information on how the patients were positioned in the lithotripter or how the authors dealt with stones in the mid ureter. It should be noted, however, that the results with lower calyx stones (77%) were very similar to those of stones in other locations (79%) and that stones measuring
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