Extracorporeal shock wave lithotripsy for the treatment of renal stones. Treatment policy is as important for success as type of lithotriptor and patient selection
L. Grenabo, K. Lindqvist, H. O. Adami, R. Bergstrom and S. Pettersson
Department of Urology, Sahlgrenska University Hospital, Goteborg, Sweden.
OBJECTIVE: To compare the efficiency of different machines for
extracorporeal shock wave lithotripsy (ESWL) of renal stones and to analyze
treatment strategies and stone characteristics as determinants of treatment
failure. DESIGN: Prospective cohort study. SETTING: Nationwide study in
Sweden. All 11 hospitals in Sweden using 1 of 7 lithotriptors in 1991 were
included. PATIENTS: The study cohort comprised 1171 (97.6%) of the 1200
patients in Sweden who underwent ESWL for the first time because of renal
stones between February 18, 1991, and December 31, 1991. MAIN OUTCOME
MEASURE: Treatment failure, defined as 1 or more residual renal stone
fragments larger than 4 mm 1 of 3 months after the end of treatment, was
analyzed after ESWL monotherapy and after ESWL plus auxiliary treatment
using a multivariate analysis. RESULTS: Treatment failure varied by center
from 12% to 48% (mean, 24%) after ESWL monotherapy and from 4% to 40%
(mean, 18%) after ESWL plus auxiliary procedures. After adjusting for
differences in the patient mix, the risk of treatment failure, measured as
the odds ratio, varied by center almost 7-fold after ESWL monotherapy and
20-fold after ESWL plus auxiliary treatment. Substantial differences also
existed for the same equipment used at different centers. The risk of
treatment failure increased rapidly for renal stones larger than 15 mm, and
it was at least 2-fold higher in patients who had multiple stones or a
cavity. CONCLUSIONS: When ESWL is used for the treatment of renal stones,
the treatment policy has as great an effect on the success rate and need
for auxiliary treatment as optimal equipment and proper patient selection.
Meaningful comparisons of different lithotriptors require multivariate
analyses with adjustment for patient selection.
