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INTRODUCTION AND OBJECTIVE: Currently, the American Urological Association (AUA) Guidelines for urolithiasis only address management of staghorn and ureteral stones. Although surgical treatment modalities for renal stones are not fully addressed in the AUA Guidelines, there is level one data confirming superiority of percutaneous nephrolithotomy (PCNL) over SWL for lower pole stones larger than 1 centimeter (>1cm). The aim was to investigate whether SWL is currently utilized for large lower pole stones, and whether higher volume SWL centers are more likely to follow level one evidence against SWL for large lower pole stones.
METHODS: We retrospectively reviewed all SWL from October 2012 to September 2013 performed within a large mobile lithotripsy consortium encompassing 22 hospitals in rural northern New England. We evaluated all hospitals within the consortium, and specifically evaluated treatment of lower pole renal calculi. Large stones were defined as larger than >1cm. Hospitals were divided in two groups based on the mean of total lower pole stones treated. We used Pearson’s Chi-Square and Wilcoxon Test for categorical variables; p<0.05 was considered significant.
RESULTS: Of 971 SWL procedures performed, there were 256 stones treated in the lower pole. Overall, 12% (31/256) of lower pole renal stones treated with SWL within the consortium were larger than 1 cm. The mean number of lower pole stones treated per hospital was 12 SD+/- 11.26. There were nine high volume hospitals that treated 12 lower pole stones or more. At the higher volume hospitals, 14% of lower pole stones were >1cm, whereas at the low volume hospitals there were only 6%. The difference between high and low volume SWL centers was not statistically significant, although there is a trend towards higher utilization of SWL for large lower pole renal stones at higher volume hospitals (p=0.08).
CONCLUSION: This large retrospective cohort shows that although SWL practice patterns are not statistically different among these 22 studied hospitals, SWL is still used to treat large lower pole stones. PCNL has been recommended over SWL for lower pole stones larger than a centimeter based on multi-institutional RCT data. If compliance with this RCT data were to be adopted as a quality measure, it would be of particular note that when specifically considering SWL, high volume SWL centers would not provide higher quality care than the lowest volume centers.