Prognostic factors for extracorporeal shock-wave lithotripsy of ureteric stones--a multivariate analysis study.
OBJECTIVE
To define factors that have a significant impact on the stone-free rate after extracorporeal shock-wave lithotripsy (ESWL) of ureteric stones using multivariate analysis.


METHODS
Between February 1992 and February 2002, a total of 938 patients with ureteric stones were treated with in situ ESWL using the Dornier MFL 5000 lithotripter. The outcome of treatment was evaluated after 3 months and failure was defined as the presence of any residual stones. The stone-free rate was correlated with patient characteristics (age, sex and radiological renal picture) and stone features (site, side, length, width, nature, opacity and the presence of ureteral stents). Factors with a significant impact on the stone-free rate using the chi (2) test were further analyzed using multivariate analysis.


RESULTS
Overall, the stone-free rate was 88.7%. Repeat treatment was required in 50.4% of cases. Post-ESWL complications were observed in 32 cases (3.4%), including static steinstrasse in 19 (2%). Auxiliary procedures were needed in 28 cases (3%). Using the chi (2) test, only three factors had a significant impact on the stone-free rate, namely stone site, the transverse diameter of the stone and the presence of a ureteral stent. The stone-free rate was highest for stones located in the lumbar ureter (436/470; 92.8%) and lowest for those located in the pelvic ureter (268/324; 82.7%) (p = 0.0017). Stones with a transverse diameter of < or =1 cm were associated with a stone-free rate of 89.7% (715/797), compared to 83% (114/141) for those with a transverse diameter of >1 cm (p = 0.017). Non-stented patients had a stone-free rate of 89.8% (732/815), compared to 81.3% (100/123) for stented patients (p = 0.006). On multivariate analysis, these three factors maintained their statistical significance. A logistic regression model was designed to estimate the probability of stone-free status after ESWL.


CONCLUSIONS
The site and transverse diameter of the stone and the presence of a ureteral stent are the only significant predictors of success of ESWL therapy for ureteric stones.
Abdel-Khalek
Mohamed
M
Urology and Nephrology Center, Mansoura University, Mansoura, Egypt. unc@mum.mans.edu.eg
Sheir
Khaled
K
Elsobky
Emad
E
Showkey
Saied
S
Kenawy
Mahmoud
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000379:methods; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011183:Postoperative Complications; D011379:Prognosis; D019233:Retreatment / Q000706:statistics & numerical data; D012307:Risk Factors; D016896:Treatment Outcome; D014514:Ureteral Calculi / Q000175:diagnosis / Q000628:therapy*; D013520:Urologic Surgical Procedures