Should we treat asymptomatic concurrent contralateral renal stones? A longitudinal analysis

The objective is to explore the need for future surgery among patients treated for asymptomatic concurrent contralateral stones versus those that were not. Upon IRB approval, we retrospectively reviewed records of patients who underwent stone surgeries (SWL, URS, PCNL) from 2009 to 2018. Patients were included if they were greater than 18 years old, had a minimum follow-up of 2 years, and had pre-operative imaging. Patients were divided into three groups: bilateral surgery, ipsilateral surgery with, and without asymptomatic concurrent contralateral stones. Cox regression was used to analyze patients' need for future surgery while controlling demographic and comorbid characteristics. Of the 1666 patients included, 51.9% were men. They were 59.7 ± 15 years and had a BMI of 31.3 ± 8.2 kg/m². During the follow-up of 5.2 ± 2.2 years (range 2-11 years), patients who had bilateral surgery and patients who had ipsilateral surgery without treatment of the asymptomatic concurrent contralateral stones had no difference in the need for future surgery (41.7% vs. 43%, p = 0.585). When stratified by stone size, patients with contralateral stones > 6 mm were more likely to require future surgical treatment than those treated bilaterally (p < 0.001). Our study demonstrates that treating asymptomatic concurrent contralateral stones does not lower the need for future surgical interventions. However, asymptomatic concurrent contralateral stones > 6 mm may portend earlier need for treatment. Therefore, bilateral treatment should be considered at presentation.