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STONE
DISEASE
When
is medical prophylaxis cost-effective for recurrent calcium stones?
Chandhoke PS
Department of Surgery (Urology), University of Colorado Health Sciences
Center, Denver, Colorado, USA
J Urol. 2002; 168:937-40
- Purpose:
Medical management is generally recommended for recurrent calcium stones
to prevent future episodes. However, in this era of extracorporeal shock
wave lithotripsy and outpatient ureteroscopy it is not known whether
medical prophylaxis is more cost-effective than treatment of recurrent
stone episodes. The cost of medical prophylaxis was compared with the
cost of clinically managing recurrent stone episodes, and the stone
recurrence rate without prophylaxis (stone frequency) at which these
2 treatment approaches became cost equivalent was determined.
- Materials
and Methods:
An international cost survey was conducted in 10 countries to compare
costs of medical prophylaxis and managing recurrent acute stone episodes.
Costs of an acute stone episode included an emergency room visit, associated
radiographic imaging to confirm diagnosis of a symptomatic stone and
outpatient treatment of upper urinary tract stones that did not pass
spontaneously. Costs of medical management included an initial limited
metabolic evaluation, drug therapy, a followup office visit every 6
months that included a 24-hour urinalysis and radiographic imaging of
the kidneys, ureters and bladder once a year.
- Results:
Costs of medical prophylaxis and managing an acute stone episode varied
significantly from country to country. The stone frequency at which
costs of these management options became equivalent ranged from 0.3
to 4 stone episodes a year.
- Conclusions:
Medical management of a first stone episode is not cost-effective. Cost
analysis should be individualized for specific health care plans to
determine which practice patterns are most cost-effective for a particular
patient with recurrent calcium stone formation.
- Editorial
Comment
Although effective diagnostic protocols and treatment regimens are available
for the diagnosis and prevention of recurrent nephrolithiasis, the cost-effectiveness
of stone metaphylaxis versus treatment of acute stone episodes as they
arise has not been thoroughly explored. In this article, the costs of
medical evaluation and management and treatment of symptomatic stone
episodes were determined world-wide from an economic survey of representative
individuals in selected countries. The point of cost equivalence, representing
the stone recurrence rate at which the cost of medical evaluation and
therapy and management of an acute stone episode were equivalent, was
determined for each country and varied between 0.32 and 0.69 in the
Unites States, depending on the estimated need of surgical intervention.
Based on their findings, the authors suggest that a medical preventative
program for the first time stone former is not cost-effective.
This important paper attempts to identify select subgroups of stone
formers in whom a medical treatment program is cost effective. In doing
so, the assumptions used in the model are of critical importance. Unfortunately,
the rate of surgical intervention varies widely in the literature and
the distribution of surgical procedures for symptomatic stones is not
well known. Furthermore, charges and not costs were used to determine
the points of cost equivalence in several countries, despite the inherent
problems involved in using the more arbitrary charge data. Nonetheless,
for well-defined patient populations (i.e., recurrent stone formers
at an institution where intervention rates and surgical distribution
is known), this model can be used to identify patients in whom a medical
treatment program is cost-effective.
Dr. Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA
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