The revised Recurrence of Kidney Stone tool predicts the risk of symptomatic recurrence by using readily available clinical characteristics of stone formers, a recent study found. Researchers used a random sample of incident symptomatic kidney stone formers in Olmsted County, MN, and followed them for all symptomatic stone episodes resulting in clinical care from January 1, 1984, though January 31, 2017. Clinical and radiographic characteristics at each stone episode predictive of subsequent episodes were identified. Among the findings:

• There were 3,364 incident kidney stone formers with 4,951 episodes.
• The stone recurrence rates per 100 person-years were 3.4 after the first episode, 7.1 after the second episode, 12.1 after the third episode, and 17.6 after the fourth or higher episode.
• Younger age, male sex, higher body mass index, family history of stones, pregnancy, incident asymptomatic stone on imaging before the first episode, suspected stone episode before the first episode, were among independent risk factors for recurrence.
• The risk of recurrence in 5 years ranged from 0.9% to 94%, depending on risk factors, number of past episodes, and years since the last episode.