Presentation Authors: Patrick Samson*, Sarah Holt, Seattle, WA, Ryan Hsi, Nashville, TN, Mathew Sorensen, Jonathan Harper, Seattle, WA
Introduction: The American Urologic Association Guidelines recommends obtaining a 24-hour urine (24HU) in recurrent stone formers, patients high-risk for stone recurrence, and interested first-time stone formers. However, the advantage of selective therapy based on 24HU results over empiric treatment is unclear. We aimed to determine if obtaining a 24HU in high risk stone formers is associated with decreased recurrent stone episodes in a contemporary cohort exemplifying real-world clinical practice.
Methods: We used the MarketScan database to identify insured, employed subjects, 18 to 64 years old with a primary diagnosis of kidney and/or ureteral stones based on ICD-9 and ICD-10 diagnosis codes from 2008 to 2014. Subjects at high risk for infectious stones or with cystinuria were excluded. High risk stone formers (based on AUA guidelines), those undergoing stone surgery, and those with previous stone diagnoses one year prior to the date of inclusion were characterized with CPT and ICD codes, as these subjects are thought to benefit the most from 24HU per the AUA guidelines. The exposure was a 24HU done within 6 months of diagnosis. The outcome was recurrent stone episodes as defined by ED visits and hospitalizations with a primary stone diagnosis or stone surgery from 6 months to 3 years after the primary diagnosis. We used adjusted logistic regression to estimate recurrence risk by 24HU exposure. We adjusted for age, gender, insurance type, year of diagnosis, high risk status, recurrent stone history, and being treated by a urologist on the multivariate analysis.
Results: We identified 422,124 subjects diagnosed with nephrolithiasis, 27,993 (6.6%) of whom had a 24HU within 6 months after their primary stone diagnosis. On multivariate analysis, completing a 24HU was not associated with recurrence rates in high risk/recurrent stone formers (OR 0.9; 95% CI [0.74-1.10] or those undergoing a surgery (OR 1.0; 95%CI [0.94-1.06]). We found no difference in 24HU utilization between men and women (6.6% vs 6.7%). A positive association of 24HU utilization was seen in high-risk vs. low risk-subjects (6.9% vs. 6.6%), recurrent vs. first time stone formers (8.7% vs 6.5%), and those treated with surgery vs. no stone surgical history (14.2% vs. 5.0%) (all p < 0.01). Recurrence rates of those who were high-risk/recurrent stone formers, had surgery and all-comers were 25.1%, 16.9%, and 12.3%, respectively.
Conclusions: Among high-risk/recurrent stone formers and those undergoing stone surgery, there are no associations observed between having a 24HU and stone recurrence at 3 years.