Relationship between Success rate of Extracorporeal Shockwave Lithotripsy (ESWL) and Body Mass Index (BMI)

Abstract

Background and Objectives: Success rate of ESWL depends on the consistency, size, shape, location, and the attenuation of urinary calculi. Body mass index (BMI), an objective measure of obesity, has been proposed as a predictor of ESWL success rate outcome; however, this hypothesis has not been confirmed yet in more controlled studies. This study was aimed to evaluate the relationship between the success rate of ESWL and the BMI. Materials and Methods: In this cross-sectional study, we evaluated 80 patients with urinary calculi who underwent ESWL during a one-year period. The patients were categorized in 4 groups based on their BMIs as following: BMI 19-24.9, BMI 25-29.9- BMI 30-34.9, and BMI ≥35kg/m2 the patients were matched regarding the age, gender, stone specifications (frequency, location, chemical components, and stone size). Six weeks after completion of ESWL, the patients were categorized into stone free (SF) group and stone residual group (SR) group. The results were analyzed and compared between groups. Results: Eighty patients (47 male, 33 Female) with the mean age of 45.66±9.03 years were studied. All patients had solitary, upper urinary tract stone. The chemical analyses showed that the calcium oxalate was the most common type in )64 patients 80%) cases. The frequencies of SF and (SR) patients were 50 (62 %) and 30 (37.5%), respectively. mean BMI in SF and SR were 42.28±4.58 and 33.85±3.66 kg/m2 respectively. BMI predictive value for stone residue had the sensitivity and 80% and 78%. Conclusion: Higher BMI leads to the more SR encountered after ESWL. This was more prevalent in those with BMI ≥30 kg/m2. BMI greater than 30 kg/m2 negatively affect the success rate of ESWL and other therapeutic measurements should be considered in this patients.

Keywords: Urinary Calculi, Body Mass Index, Lithotripsy