Regional Variation in Rate of SWL Utilization among Patients with Nephrolithiasis
Gina N. Tundo, MD; Vernon M. Pais, Jr., MD
Dartmouth Hitchcock, Lebanon, NH
Nephrolithiasis is rising in prevalence and continues to pose an increasing financial burden on society. Common management options for stones include watchful waiting, percutaneous stone removal, ureteroscopy and shockwave lithotripsy (SWL), with the latter two comprising the majority of interventions for stones in the US. When multiple treatment options exist, effective care is heralded by equal utilization rates in disparate locations. Conversely, if variation is identified, this may be secondary to unwarranted variation, potentially driven by either supply-sensitive or preference-sensitive care. Responsible healthcare spending dictates identification of variation in surgical utilization as a first step in unravelling and then addressing underlying sources of potentially unwarranted variation. Variation in the utilization of SWL has been suspected but not comprehensively evaluated in the United States.
Utilizing the full 100% Medicare dataset from the year 2014, we identified all patients with the diagnosis of a renal stone within the previously defined and validated 306 hospital referral regions (HRR's) of the US. Among beneficiaries with the diagnosis of a renal stone, we then assessed the rate of any type of surgical management of the stone, and then specifically the rate of use of SWL, both on a national level and by HRR. Both crude rates and rates adjusted by age, sex and race were generated.
In 2014 there were a total of 806,652 included Medicare beneficiaries with a diagnosis of a renal stone. Nationally, the rate of any surgical intervention was 71.34/1000. The HRR with the lowest rate of surgical intervention was 31.67/1000 while that with the highest was 131.02/1000, representing an approximately 4-fold variation in the rate of all surgical management.
For SWL, the national rate of utilization was 45.48/1000 patients with kidney stones. The HRR with the lowest rate of SWL utilization was 9.24/1000 while that with the highest was 105.80/1000, representing a greater than 11-fold variation in SWL utilization among those with stones.
In this all-inclusive population of Medicare beneficiaries with a diagnosis of a renal stone, there is dramatic variation in the rate of SWL utilization. Although this may reflect overutilization of SWL in some centers and underutilization in others, these findings clearly suggest that the probability of having SWL as opposed to any other management option for a stone may depend heavily upon the hospital to which one is referred. Whether this is due to supply-sensitive factors, including the availability of a lithotripter or number of urologists on staff, or preference-sensitive factors, including the physician's preferred treatment, warrants further investigation. Future efforts to standardize treatment algorithms and develop shared decision making models may reduce unwarranted variation in the care of patients with kidney stones.
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