OBJECTIVE • To evaluate the impact of primary prevention of stones using a strategy of increased fl uid intake. SUBJECTS AND METHODS • A Markov model was constructed and analysed using Excel to calculate and compare the costs and outcomes for a virtual cohort of subjects with low vs high water intake. • A literature search was used to formulate assumptions for the model including an annual incidence of urolithiasis of 0.032%, annual risk of stone recurrence of 14.4% and 40% risk reduction in subjects with high water intake. • Costs were based on resource utilisation from the Delphi panel and official price lists in France. • Outcomes were based on payer perspective and included direct and indirect costs and loss of work. RESULTS • The base-case analysis found total cost of urolithiasis is € 4267 with direct costs of € 2767, including cost of treatment and complications. The annual budget impact for stone disease based on 65 million inhabitants is € 590 million for the payer. • The use of high water intake by 100% of the population results in annual cost savings of € 273 million and 9265 fewer stones. Even if only 25% of the population is compliant, there is still a cost saving of € 68 million and 2316 stones. • The model was evaluated to determine the impact of varying the assumptions by ± 10%. For example, when the incidence of stone disease is increased or decreased by 10% then the mean (range) baseline cost will change by € 59 (531-649) million for the payer and savings will either increase or decrease by € 27 (246-300) million. • The largest impact on cost savings occurs when varying risk reduction of water by 10% resulting in either a mean (range) increase or decrease by € 35 (238-308) million. • Varying cost of stone management by 10% has an impact of ± € 17 million. Varying other factors such as stone recurrence by 10% has only an impact of ± € 9 million and varying risk of chronic kidney disease ± € 1 million, as they affect only a portion of the population. CONCLUSIONS • The budget impact analyses show that prevention of nephrolithiasis can have a significant cost savings for a payer in a healthcare system and reduce the stone burden significantly. • Future studies will need to assess the feasibility and effectiveness of such an approach in a population.
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