WCE 2017: Stone Size at Initial Presentation at a Tertiary Care Center: Demographics
The study reviewed retrospectively data from 1004 patients undergoing surgical treatments including Shock Wave Lithotripsy (SWL), Ureteroscopy (URS), and Percutaneous NephroLithotomy (PCNL) for urinary lithiasis. Demographics information including ethnicity, age, BMI and stone size (<2.0, 2-4, and >4 cm in the longest dimension) were recorded. Independent t-test was used to analyze continuous variables. Chi-squared or fisher exact test was used to analyze categorical variables.
Data analysis showed that among 1004 patients, 60%, 25%, and 15% of patients had stone size of <2 cm, 2-4 cm, and >4 cm, respectively. There was no significant difference in stone size between men and female (48.2%)(p = 0.92). There was significant difference in mean ages with different stone sizes: 49.3 ± 7.8 for stone size <2 cm, 55.8 ± 14.7 for stone size 2-4 cm, and 57.2 ± 13.9 for stone size >4cm (p < 0.001). There was significant difference in mean BMI with different stone sizes: 29.6 ± 7.8 for stone size <2 cm, 31.1 ± 7.6 for stone size 2-4 cm, and 31.3 ± 7.6 for stone size >4 cm (p < 0.01).
In terms of ethnicity, 15% of patients belonged to minority groups. Of that 15%, 58% was African American, 35% was Hispanic, and 7% was other ethnicity. There was significant difference in stone size compared between all minority groups and Caucasians respectively: 52% vs. 62% for stone size <2 cm, 32% vs. 24% for stone size 2-4 cm, and 16% vs. 14% for stone size >4cm (p = 0.0477).
In terms of age at stone presentation, there was 11% of patients at 21-30 years old, 14% at 31-40 years old, 17% at 41-50 years old, 23% at 51-60 years old, 21% at 61-70 years old, 10% at 71-80 years old, and 2% at over 80 years old. There was an increase of stone frequency per decade of age, peaking in the fifth decade. It was more common for the sixth decade of age having stone size 2-4 cm when being compared with other age groups.
Dr. Wardenburg discussed that higher age and BMI were correlated with larger stones presented in a tertiary care center. It was possible that there was a delayed diagnosis or a delayed in initial presentation for treatment because of competing health issues or referral patterns from the community. It should be noted that 34% (n = 341) of patients was ≥ 60 years old. Therefore, this study was believed as the largest study of its kind in this age group.
As a conclusion, Dr. Wardenburg stressed that increased age, higher BMI, and minority status at time of presentation at a tertiary center were correlated with larger stones. Because larger stones are often correlated with more invasive and higher number of surgical treatments, the findings were clinically significant in these groups of patients. Future studies were necessary to determine possible factors being responsible for these health disparities.
Presented by: Marla Wardenburg, MD
Authors: Marla Wardenburg, MD; Jeannette Brown; Rupam Ruchi; Xuerong Wen; Vincent Bird, MD; Victoria Y. Bird, MD
Affiliation: Department of Urology, University of Florida; Division of Nephrology, Department of Medicine, Department of Biomedical Engineering, University of Florida
Written by: Long Hoang, Department of Urology, University of California-Irvine at 35th World Congress of Endourology– September 12-16, 2017, Vancouver, Canada.