Presentation Authors: Shuang Li*, Simone L. Vernez, Kristina L. Penniston, R. Allan Jhagroo, Stephen Y. Nakada, Madison, WI
Introduction: Epidemiological studies have explored stone recurrence rates according to stone composition. However, longitudinal studies have not been performed to examine the association between stone composition and need for repeat surgery. The objective of this study was to explore the association between stone composition and surgical recurrence.
Methods: Patients who underwent stone surgery at our institution between 2009-2017, were followed for â‰¥1 year, and had â‰¥1 stone composition analysis were identified. Stone composition was defined as the predominant component (>50%); the stone analysis closest to surgery was used. Repeat surgery was defined as the second surgery on the same kidney unit. Planned staged surgery for one stone was not considered repeat surgery. Cox regression analysis was used.
Results: Of patients included (n=944), 52% were men. Mean age was 59.0Â±15.0 y; mean BMI was 31.1Â±8.2. The time from stone analysis to surgery was 5.7Â±15.7 months. Most patients had undergone ureteroscopy (75.1%), while 19.4% and 5.5% had undergone percutaneous lithotomy and shock-wave lithotripsy, respectively. Over 4.9Â±2.4 y (median 4.8 y) of follow-up, 27.6% of patients required repeat surgery. Patients&[prime] stone compositions were calcium oxalate (69.3%), calcium phosphate (14.2%), uric acid (9.1%), struvite (2.5%), and cystine (1%). Patients with stones of some other composition (n=37) were excluded from our analysis due to small sample size. Survival analysis showed that patients with predominantly calcium oxalate or uric acid stones had a lower risk of repeat surgery. Those with predominantly cystine, calcium phosphate, or struvite had significantly higher risk of surgical recurrence compared with calcium oxalate (p < 0.001, p < 0.001, and p=0.05, respectively).
Conclusions: Patients with cystine, calcium phosphate, or struvite stones had more surgical recurrence compared to patients with calcium oxalate stones. There was no significant difference between calcium oxalate and uric acid stone formers for surgical recurrence. This finding can be used in counseling patients about their surgical stone risk and in managing expectations.