AUA 2019: Effect of Stone Composition on Surgical Stone Recurrence: Single Center Longitudinal Analysis

Chicago, IL ( One of the main questions of Dr. Shuang Li’s study was to see if stone composition effect stone recurrence. She notes that a previous study found that Calcium oxalate was the least recurrent at about 30%, while brushite, struvite, and uric acid stones were at about 50%. She found that the best way to document recurrence was to track the need for a repeated surgery.

The stone compositions were separated into 6 categories and were placed in only one of the categories following sequential order: struvite, cystine, uric acid, brushite, calcium oxalate (≥50%), apatite (≥50%). It is important to note that about 63% of these patients have had a history of stone before their 1st surgery. Dr. Li highlights that the highest composition of stone was calcium oxalate which made up 65.5% of the stones. One important result to note is that brushite made up 5.9% of the stones. 

A survival analysis that showed brushite and cysteine had the highest rates of recurrence, with calcium oxalate having the lowest rate of recurrence. Dr. Li concludes that when calcium oxalate was used as a reference group in a hazard ration, all of the other stone compositions had a statistically significant value. The stones were then separated into three risk groups: high, intermediate, or low. Cystine and brushite were considered high risk, struvite uric acid, and apatite stones were intermediate risk, and calcium stones were in the low risk category. 

During the question portion of the presentation, it was pointed out that a limitation to this study was that not all patients were considered stone free after their initial surgery. This would result in a possible flaw in that data set, which would have most likely changed the outcomes. Another possible limitation was that only 34% of the patients had metabolic evaluation from a nephrologist or dietician.

Presented by: Shuang Li, MD, Billings Clinic, and St. Joseph Hospital-Eureka, Internal Medicine Cutten, CA
Co-authors: Shuang Li, Simone L. Vernez, Kristina L. Penniston, R. Allan Jhagroo, Sara Best, Stephen Y. Nakada, the University of California, San Francisco

Written by: Joshua Tran, (Department of Urology, University of California-Irvine) at the American Urological Association's 2019 Annual Meeting (AUA 2019), May 3 – 6, 2019 in Chicago, Illinois