Abstract

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• INTRODUCTION/

  OBJECTIVE:

  We examined the potential correlation between Charlson comorbidity index (CCI) and stone free rate after extracorporeal shock wave lithotripsy (ESWL).

  MATERIALS AND METHODS:

  Two hundred twenty-six adult patients were treated with 241 ESWL procedures for a renal or ureteral stone(s) over a 3 year period. Age, race, comorbidities, CCI, stone size and location, number of shocks and power level were determined. Treatment efficacies were evaluated at a mean of 56.1 days after each ESWL with computed tomography, abdominal x-ray, intravenous pyleography and/or renal ultrasound. Multivariate logistic regression analysis was performed.

  RESULTS:

  There was no correlation between CCI and any of the following: stone burden, number of shocks, or power level. There was no difference in stone burden, number of shocks or power level between those who were and were not stone free. Stone free rates for patients with CCI of zero, one, and two or greater were 44.7% (71/159), 27% (13/48) and 41.2% (14/34) respectively. Patients with an index of one were 2.1 times more likely to have a residual stone burden than patients with an index of zero (95% CI 0.99-4.42, p = 0.05). Patients with one comorbidity were 2.4 times more likely to have a residual stone burden than patients with none (95% CI 1.04-5.72, p = 0.04). Patients with upper ureteral stones were less likely to have a residual stone burden than patients with renal stones (RR = 0.52, 95% CI 0.27-0.98, p = 0.04). Those with lower ureteral stones were less likely to have a residual stone burden than those with renal stones (RR = 0.20, 95% CI 0.09-0.43, p **0.0001). The only significant predictors of the stone free rate were stone location and number of comorbidities.

  CONCLUSIONS:

  Stone location and number of comorbidities were significant predictors of ESWL outcome. The CCI may underestimate the magnitude of comorbidities and their effect on stone treatment efficacy.