Should we support prophylactic intervention for asymptomatic kidney stones? A retrospective cohort study with long-term follow-up

The purpose of this study was to evaluate the long-term outcomes of patients undergoing prophylactic intervention or active surveillance for asymptomatic kidney stones and identify factors influencing the outcomes. In this retrospective cohort study, we reviewed the medical records of patients with asymptomatic kidney stones in two institutes between November 2014 and November 2019. Standardized questions were asked via phone calls to supplement the outcomes. Pain, hydronephrosis, stone growth, serious infection, gross hematuria, and spontaneous passage were defined as stone-related events. Future intervention was also recorded to evaluate management. A total of 101 patients with 120 kidney units were enrolled in this study. The median follow-up time was 63 months. The patients were classified into the control group (79 cases) or exposure group (41 cases) according to whether they underwent prophylactic intervention before any stone-related events. Generally, the rates of stone-related events and future intervention were significantly different between the two groups (57.0 vs. 12.2%, p < 0.001; and 31.6 vs. 4.9%, p = 0.002, respectively). After applying stabilized inverse probability of treatment weighted, Cox regression suggested that patients who underwent prophylactic intervention were less likely to experience stone-related events and future intervention (HR = 0.175, and HR = 0.028, respectively). In conclusion, patients who underwent prophylactic intervention had a lower risk of stone-related events and future intervention, although they had some slight complications.