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OBJECTIVE To determine if obtaining a 24-hour urine collection (24HU) in stone formers is associated with decreased recurrent stone episodes. METHODS Using the MarketScan database, adults 17-62 years old with nephrolithiasis were identified between 2007 and 2017 with a minimum of 3-year follow up. High-risk stone formers, those undergoing stone surgery, and those with history of recurrent stones were identified. The exposure was a 24HU within 6 months of primary diagnosis. The outcome was recurrent stone episodes—defined by stone-related emergency room visits, hospitalizations, or stone surgery 90 days to 3 years after diagnosis. Logistic regression was used to estimate recurrence risk by 24HU exposure for the overall cohort and sub-cohorts limited to known recurrent stone formers, high-risk subjects, and those having stone surgery. RESULTS Of 434,055 subjects analyzed, 30,153 (6.9%) had a 24HU. An annual decline in 24HU utilization was seen (7.5%-5.8%). Regional variation in usage rate was also observed. On multivariate analysis, completing a 24HU was not associated with risk of recurrence in any of the following cohorts: recurrent stone formers (OR 0.98, 95% CI 0.9-1.07), both high risk and recurrent stone formers (OR 0.95 [0.8-1.13]), those undergoing surgery (OR 1.02 [0.97-1.07]); a positive association with 24HU and recurrence was seen in those labeled high-risk (OR 1.08 [1.01-1.16]) and in all-comers (OR 1.15 [1.12-1.19]). CONCLUSION The 24HU was not associated with decreased recurrence rates in the overall population nor in higher risk sub-cohorts.

OBJECTIVE To determine if use of the hematuria risk index can reduce testing and cost, while maintaining equivalent lesion detection in patients with asymptomatic microscopic hematuria. MATERIALS AND METHODS Retrospective cohort study of 1049 patients at single institution. Hematuria risk index score was calculated based on clinical factors including age, sex, smoking history, and degree of hematuria for each patient along with evaluation studies performed and total number of tumors discovered. Cost benefit analysis was performed based on published Medicare averages. RESULTS Tumor detection rate in overall, low-risk, and moderate-risk groups were 1.2%, 0%, and 2.96% at a total cost of $408,376. When low-risk group is not screened cost decreases to $166,252 with no lesions missed. The cost to discover one lesion/cancer in the overall group was $34,031.3, the cost to find one high-grade clinically significant lesion/cancer was $136,125.3 for the overall group. When the low-risk group was removed, the cost to find a high-grade clinically significant lesion/cancer decreased to $55,417.3 without missing any significant lesions. Ultrasound may be utilized instead of computed tomography with minimal loss of lesion detection in select moderate risk patients. CONCLUSION None of the low-risk hematuria risk patients were diagnosed with any lesions, as such these patients may not need an evaluation. Furthermore, by utilizing a risk-stratified approach to the assessment of asymptomatic microscopic hematuria health care costs can be significantly decreased with limited negative consequences in terms of lesion detection.