Prognosis after extracorporeal shock wave lithotripsy of radiopaque renal calculi: a multivariate analysis

To obtain a better understanding of the prognostic factors influencing treatment outcome after extracorporeal shock wave lithotripsy (ESWL), a multivariate logistic analysis of the data from 246 patients has been undertaken. All of the patients were treated with the Dornier lithotriptor HM-3 for radiopaque renal calculi. Treatment success was defined as stone-free within 3 months of one ESWL session and without adjuvant measures after ESWL. In a first analysis, 210 patients with solitary and multiple calculi without adjuvant measures before ESWL were studied. Of 210 patients, 141 (67%) were free from stones after 3 months). Significant influences on the success rate were body mass index and stone number. In a second analysis only those 160 patients with solitary calculi were considered. In this group, age, body mass index, stone location, stone burden and serum calcium significantly influenced the prognosis. When patients with adjuvant measures were added to the analysis an increasing prognostic importance of the stone burden was seen. In patients with a small to medium stone burden (< 4.0 cm3), the number of stones seemed to be more important than the stone burden. Patients appear to have the best chance for successful ESWL when their body mass index is between 20 and 28, their age is between 40 and 60 years, their stones are in the renal pelvis and solitary, the stone burden is < 1.0 cm3, and when their serum calcium is normal.