Variation in clinical outcome following shock wave lithotripsy

Purpose: We measure and compare operator specific success rates of extracor poreal shock wave lithotripsy (ESWL*) performed by 12 urologists in 1 unit to determine interoperator variation. Materials and Methods: From January 1, 1994 to September 1, 1997 a total of 5,769 renal and ureteral stones received 9,607 ESWL treatments by 15 urolo gists with a Dornier MFL 5000* lithotriptor. The S-month followup data are available for 4,409 stones. Outcome measures consisted of patient demograph ics, stone characteristics, technical details of lithotripsy, and stone-fre e and success rates by treating urologists. Results: Treatment results were analyzed for 12 urologists (surgeons A to L ) who treated more than 100 stones each, totaling 4,244 with followup infor mation available. Mean stone-free and success rates were 50.6% and 72.3%, r espectively. Surgeon A had significantly higher stone-free and success rate s of 56.2% and 76.7%,respectively(p <0.05), with treatment results from 877 stones, which was a significantly higher number than others (p <0.05). Sig nificant differences existed in mean number of shocks delivered among urolo gists (p = 0.0001), with surgeons A and J delivering the highest mean numbe rs (2,317 and 2,801, respectively). There was no difference in treatment du ration (p = 0.75) but variation existed among urologists in terms of mean m aximum treatment voltage (p = 0.0001). Mean fluoroscopy time at 4.1 minutes was higher for surgeon A than others (p <0.05). Mean complication rate fol lowing ESWL was 4.9% with no difference among urologists (p = 0.175). Re-tr eatment was required in 21.7% of cases and surgeon A had the lowest rate (1 5.9%, p <0.05). Conclusions: We demonstrated clinically and statistically significant intra -institutional differences in success rates following ESWL. The best result s were obtained by the urologist who treated the greatest number of patient s, used a high number of shocks and had the longest fluoroscopy time. Accur ate targeting is crucial when using a lithotriptor, such as the Dornier MFL 5000, with a narrow focal zone of 6.5 mm. in diameter. Other centers shoul d be encouraged to develop similar programs of outcome analysis in an attem pt to improve performance.