Increased water intake as a prevention strategy for recurrent urolithiasis: major impact of compliance on...

We evaluated the economic impact of preventing recurrent stones using a strategy of increased water intake and determined the impact of compliance on cost-effectiveness for the French health care system.

A Markov model was constructed to compare costs and outcomes for recurrent kidney stone formers with less than 2 L vs 2 L or more daily fluid intake. Model assumptions included an annual prevalence of 120,000 stone episodes in France, 14.4% annual risk of stone recurrence and a 55% risk reduction in subjects with adequate water intake. Costs were based on resource use as estimated by a panel of experts and official national price lists. Outcomes were from the perspective of the public health payer, and encompassed direct and indirect costs.

The total cost of an episode of urolithiasis was estimated at €4,267 including the cost of treatment and complications. This corresponds to an annual budget impact of €88 million for recurrent stones based on 21,000 stone events. Assuming 100% compliance with fluid intake recommendations of 2 L daily, 11,572 new stones might be prevented, resulting in a cost savings of €49 million. Compliance with water intake in only 25% of patients would still result in 2,893 fewer stones and a cost savings of €10 million. Varying the costs of managing stones had a smaller impact on outcomes since in many patients stones do not form. Varying the incidence of complications did not change the incidence of stones and had a negligible effect on overall cost.

Preventing recurrent urolithiasis has a significant cost savings potential for a payer as a result of a reduced stone burden. However, compliance is an important factor in determining cost-effectiveness.