Evidence for durable kidney stone prevention over several decades.

Abstract

To analyse three outcomes of stone prevention strategies in one clinic devoted to that activity since 1969, i.e. stone recurrence rates, stone-related procedures and 24-h urinary stone risk factor, to assess whether such treatment can be maintained over long periods. We selected 2509 patients with at least one laboratory follow-up after initial clinical and laboratory evaluation. We divided them into five time cohorts of 5, 10, 15, 20 and >20 years of follow-up. Rates of new stones and stone-related procedures, and 24-h urinary stone risk factors were compared between the cohorts using analysis of variance and general linear modelling. Stone rates and rates of stone-related procedures declined in all five cohorts, as did 24-h urinary stone risk indices. We found no diminution of treatment effects for any of these three over time. Those patients who remained under active care had significant reductions in stone recurrence and rates of stone-related urological procedures for up to >20 years. However, only a small fraction of patients who entered the clinic remained for such long periods. Urine testing substantiates impressive and sustained reductions in supersaturation, the principle driving force for stone formation. Overall, for those patients willing to remain in continuous treatment for periods of up to three decades, medical stone prevention appears to be effective in maintaining low recurrence and procedure rates.