By Deborah Borfitz
February 14, 2019 | Mayo researchers have significantly improved their predictive Recurrence of Kidney Stone (ROKS) tool by making it applicable to patients who have already had two or more attacks. The revised model, developed by a new study published in Mayo Clinic Proceedings, uses 13 readily available clinical characteristics of stone formers.
“Some of the risks we identified were known and others not,” says study co-author John Lieske, M.D., director of the Mayo Clinic’s O'Brien Urology Research Center. “But this Is the first time they have been combined into a single tool/questionnaire that gives a quantitative estimate specific for a given patient.”
Newly discovered are that higher body mass index and pregnancy at the last episode predict kidney stone recurrence. More granular radiographic predictors in the revised RKS tool include “any lower pole or pelvic kidney stone, number of kidney stones, and diameter of the largest kidney stone,” according to the published study.
One of the key findings is that the number of past episodes increases the risk of future ones up until the fourth or fifth kidney stone recurrence, possibly because stone formers learn to “self-manage … without clinical care,” the study says. “Prevention interventions were themselves a marker of recurrence,” the authors wrote.
The ROKS tool predicts the likelihood of a subsequent, symptomatic stone attack “in the next two, five or 10 years,” says Lieske. “This in turn can help the patient and caregiver decide how aggressive they want to be with diet changes and drugs.”
Since the tool is available as an online app, anyone could theoretically use it, adds Lieske, although “not all patients would be able to do it themselves.” The tool could also be used “to help power a study and select patients more likely to have a recurrence to enroll in a clinical trial.”
The study looked at a random sample of symptomatic kidney stone formers in Olmsted County, Minnesota, who were followed for all symptomatic stone episodes resulting in clinical care between January 1984 and January 2017. The data were obtained from the Rochester Epidemiology Project that provides access to medical records from most medical institutions in the county.