'Low-Risk' Kidney Stone Removal May Be Risky and Costly

Laurie Barclay, MD

April 29, 2014

After low-risk procedures to remove urinary stones, 1 in 7 patients need an unplanned emergency visit at substantial cost, according to a study published in the May issue of Surgery.

"Emergency department care is an all-too-common side effect for patients undergoing kidney stone removal surgery, when it should be a routine, outpatient procedure," lead author Charles Scales, MD, a surgeon at Duke University Medical Center in Durham, NC, said in a news release. "No one should have to roll the dice when it comes to the risk and overall cost of follow-up care for a very common procedure."

Although the Affordable Care Act has recently imposed financial penalties for unplanned follow-up care, unplanned postsurgical care for patients with kidney stones is not well-understood. The goal of this study was to examine the frequency, variation, and costs of unplanned, high-urgency follow-up visits for privately insured patients undergoing percutaneous nephrostolithotomy, ureteroscopy, or shockwave lithotripsy for stones.

The researchers searched the Marketscan database for individuals who underwent a procedure for kidney stones between 2003 and 2011. The Marketscan database covers 170 million United States residents who are covered by private health insurance.

Among 93,523 initial procedures for stone fragmentation or removal, 1 in 7 (n=12,478; 13%) was followed by an unplanned visit or hospital admission within 30 days of the procedure. This included 12% of patients who had undergone shockwave lithotripsy, 15% of those who underwent ureteroscopy, and 15% of those who underwent percutaneous nephrostolithotomy.

The authors note that the most common reasons for the unplanned follow-up visit were pain (16%), infection (10%), bleeding (1.5%), and renal failure (1.4%).

"An estimated 70 percent of follow-up procedures occurred in the emergency room," Dr. Scales said in the release. "Additional, unexpected care after a common procedure places an undue cost burden on both the patient and an overtaxed health care system."

Unplanned Visits Less Likely After Procedures at High-Volume Facilities

Multivariate analyses showed that unplanned visits were significantly less likely after procedures at high-volume facilities (odds ratio [OR], 0.80; 95% confidence interval [CI], 0.74 - 0.87; P < .001), suggesting that some unplanned follow-up care may be preventable. Most patients in the study were relatively healthy, but older patients with more comorbidities were more likely to need unplanned follow-up treatment.

Among patients who had an unplanned postprocedural visit, adjusted incremental costs per episode were greater after shockwave lithotripsy ($32,156; 95% CI, $30,453 - $33,859) than after ureteroscopy ($23,436; 95% CI, $22,281 - $24,590). The potential financial effect of each unplanned follow-up episode ranged from just over $23,000 to more than $47,000.

Limitations of this study include use of claims-based analysis lacking important clinical details and possible misclassification bias.

"Our results suggest that unplanned, high-acuity visits after procedures are not uncommon in this patient population and can be quite costly," the authors conclude. "Furthermore, the identification of a volume-outcome relationship suggests that mutable factors, such as processes of care, may influence the risk of unplanned post-procedure visits. These results should prompt efforts to identify preventable causes of unplanned care, and design interventions to reduce the occurrence of this complication of stone surgery."

The National Institute of Diabetes and Digestive and Kidney Diseases and the Urologic Diseases in America Project supported this study. Dr. Scales was supported by the Robert Wood Johnson Foundation Clinical Scholars program and the US Department of Veterans Affairs.

Surgery. 2014.


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