Cost-effectiveness of primary prevention strategies for nephrolithiasis.

PURPOSE: Stone disease is a highly prevalent condition associated with substantial cost and morbidity. We evaluated the cost-effectiveness of a primary prevention strategy.
MATERIALS AND METHODS: A decision analysis model was constructed to compare the cost of ad hoc management of symptomatic stones vs the cost of primary prevention. A literature search was performed to determine the incidence of stone disease, the effectiveness of nonmedical prevention strategies and cost associated with stone management. One and 2-way sensitivity analyses were performed to determine conditions under which a strategy of primary prevention might be cost-effective.
RESULTS: Assuming a 1% incidence of stones, a 50% risk reduction and a $100 cost per individual per year for primary prevention, the model was used to calculate the overall costs per individual per year without and with a primary prevention strategy of $46 and $123, respectively. One-way sensitivity analyses indicated that primary prevention was cost-effective if the incidence of stones exceeded 4.3% yearly or the cost of prevention was less than $23 per person yearly. Varying other factors (risk reduction, probability of requiring surgery, hours of lost work, emergency room cost) failed to reach cost equivalence under any circumstances or required unrealistic assumptions. Preventive strategies were more costly than no prevention unless the incidence of stone disease was at least 1%, the cost did not exceed $20 per person per year and the prevention strategy was at least 50% effective in preventing stones.
CONCLUSIONS: Primary prevention strategies for stone disease have not been sufficiently evaluated but can theoretically be cost-effective if the population has a sufficiently high incidence of stone disease and the strategy is of low cost and moderately effective.