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Cost-effectiveness of medical management strategies for nephrolithiasis.

PURPOSE
We evaluated the cost-effectiveness and stone recurrence rates of common management strategies in stone formers.


MATERIALS AND METHODS
A decision tree model was created to compare the costs of 6 medical treatment strategies, namely dietary measures alone (conservative), empiric drug treatment (empiric), or directed drug therapy based on simple or comprehensive metabolic evaluation. The model assumed cost accrual for evaluation, medications, emergency treatment and surgery for stone recurrence. We determined recurrence rates, medical evaluation sensitivity and the risk reduction of medical treatments from the literature and the costs of surgery, emergency room and medical evaluation at our county hospital. Drug costs were obtained from 2 national pharmacy chains.


RESULTS
In first time stone formers conservative treatment was the least costly strategy and it yielded a stone formation rate of 0.07 stones per patient yearly. In recurrent stone formers conservative treatment was less costly than drug treatments but it was associated with a higher stone recurrence rate (0.3 stones per patient yearly). The remaining drug treatments were more costly than conservative treatment ($885 to 1,187 vs $258 yearly) but they further decreased recurrence rates by 60% to 86%. Modified simple medical evaluation and management (SMEM), that is drug treatment in all patients after simple evaluation) was slightly more costly than empiric treatment and minimally more effective. Comprehensive evaluation and treatment offered no advantage in cost or efficacy over empiric treatment or modified SMEM.


CONCLUSIONS
In first time stone formers conservative therapy is cost-effective and efficacious. In recurrent stone formers conservative therapy is unsatisfactory despite low cost because of a high recurrence rate. Modified SMEM and empiric therapy yield the same cost and efficacy as treatments that follow comprehensive evaluation. However, modified SMEM may be advantageous because it offers useful additional medical information.