Influence of Body Mass Index on the Surgical Outcomes of Flexible Ureteroscopy for Pediatric Upper Urinary Tract Aalculi—A Single Surgeon Experience

Abstract

To examine the association between body mass index (BMI) and surgical outcomes of flexible ureteroscopy (FURS) for pediatric upper urinary tract calculi and to estimate the influence of BMI percentile on the learning curve of pediatric FURS. We reviewed our prospectively maintained database containing children who had kidney or ureteral stones from June 2014 to April 2019. We calculated BMI and plotted it on the Centers for Disease Control and Prevention growth chart for sex and age to estimate BMI percentile. Patient demographics, intraoperative data, stone characteristics, stone-free rate (SFR), and complication rate (CR) were analyzed. Learning curves stratified by BMI percentile groups were generated. The final analysis included 161 children, of whom 63 (39.1%) had upper body weight percentile (UBW), 64 (39.8%) had normal body weight percentile (NBW), and 34 (21.1%) had lower body weight percentile (LBW). The median stone burden of the 3 groups were 1.14 (IQR 0.50-3.41), 1.13 (IQR 0.70-3.14), and 0.95 (IQR 0.50-1.77), respectively (P=.17). The SFRs were 90.5% (57/63) in the UBW group, 81.2% (52/64) in the NBW group and 70.6% (24/34) in the LBW group (P=.04). The CRs were 15.9% (10/63), 21.9% (14/64), and 29.4% (10/34), respectively (P=.29). The learning curves showed that the SFR of FURS could be improved after about 100 cases. And decreasing BMI could steepen the learning curve of SFR. BMI is associated with the SFR of FURS. LBW children had the lowest SFR compared to UBW and NBW children. Lower BMI percentile makes the success of FURS more challenging.