Cost‐effective Strategies for Stone Management

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Cost‐effective Strategies for Stone Management

Justin I. Friedlander^1,2 & Eric M. Ghiraldi²

¹ Fox Chase Cancer Center, Philadelphia, PA, USA

² Department of Urology, Einstein Healthcare Network, Philadelphia, PA, USA

Introduction

The economic impact of nephrolithiasis is as important as ever as disease prevalence continues to rise. The most recent National Health and Nutrition Examination Survey (NHANES; 2007–2010) data indicate that kidney stones will affect nearly one in 11 (8.8%) people in the United States, up from 5.2% in 1988–1994 and 3.2% in 1976–1980 [1, 2]. In 2000 it was estimated that spending on treatment of urolithiasis eclipsed US$2 billion, nearly double that spent just 6 years previously ($1.37 billion) [3]. Other estimates suggest an additional cost of urolithiasis treatment of $1.24 billion/year by 2030 if the prevalence of diabetes and obesity continue to rise along with expected population growth [4]. Additionally, as stone disease is most prevalent among working‐age individuals, lost work hours contribute a substantial indirect cost [5]. Taken together, these statistics highlight the considerable economic impact of stone disease, for both the individual and society as a whole.

Assessing and analyzing cost

The reality of limitations on available resources increasingly requires that physicians understand the influence of economics, or, more simply, cost, in terms of how medical care is delivered. Healthcare economics influences the availability of operating room equipment/instruments and disposables, patient access to medication, and in the setting of such limitations physicians must consider not only efficacy but also cost when selecting treatments.

The definition of cost often varies with the perspective of the group that bares the cost, making it anything but consistent to measure. Patient cost refers to out‐of‐pocket expenses for a given treatment. This can vary significantly by insurance status, which in countries like the United States can be related to employment, with related deductible or co‐pays required. Societal cost is another term, one that can have a drastically different meaning depending on the healthcare system. For instance, there is a direct impact on the nation’s budget for countries like Canada or the United Kingdom with national healthcare systems, whereas in the United States only the healthcare needs of selected groups are covered by government‐funded programs such as Medicaid or Medicare, which ties the healthcare economics to overall budgetary concerns. This is not to mention cost of capital and disposable equipment as well as the level of subsidization, which will undoubtedly vary by country [6]. Common to all countries are indirect economic costs, which are sometimes even harder to quantify. Examples of indirect costs include lost wages secondary to illness and/or treatment.

It is typically much easier to define hospital costs and expenditures; thus, much of the research on healthcare costs are from the hospital’s perspective. Despite the fact that hospital costs will undoubtedly vary between centers and countries, many shared concepts exist in this space: the purchase and maintenance costs of capital equipment such as lithotripters, the cost of labor for both physicians and other healthcare workers, medication costs, and services and supplies used during hospitalization.

Not to be overlooked, any discussion involving the financial impact of treatment requires distinguishing the terms “charge” and “cost.” Charge includes both the direct cost of an item/service and the indirect cost associated with its supply. Cost most commonly refers to the direct cost to the hospital to provide a service or purchase an item. One big difference is that charge involves a defined profit margin whereas cost does not. The cost‐to‐charge ratio usually varies between surgical procedures. For example, a hospital may choose to collect a larger profit margin from one particular service than another despite a lower actual cost. Overall charge appears on the bill, although its components are often difficult to identify. The most accessible data to researchers are often the hospital billing statement; thus charges are unfortunately frequently used when performing cost analyses. The arbitrary nature of charge data means that it may not consistently relate to actual cost; however, cost data, as previously mentioned, are not without their own inherent flaws.

Lastly, medical decision‐making should include outcomes other than cost considerations. Other variables such as stone parameters, patient factors and preferences, available equipment, and surgeon preference may, in many situations, outweigh cost considerations in selecting the best stone treatment option for a given patient.

The remainder of this chapter will discuss cost with respect to diagnosis and treatment of ureteral stones, renal stones, and medical management to prevent stone recurrence.

Ureteral stones

Treatment of ureteral stones requires consideration of the following factors: diagnosis, determining the need for surgical intervention, and, if surgery is necessary, choosing the optimal surgical treatment. Each decision along the course of treatment has associated cost considerations that impact the overall cost for each treatment strategy.

Diagnosis

For many years now computed tomography (CT) has been the gold‐standard imaging modality for diagnosing ureteral stones. CT scanning has a sensitivity of 98% and a specificity of 95–100% for diagnosing calculi [7, 8] and can also more frequently diagnose the etiology of pain when calculi are not present [7]. In recent years ultrasound (US) has challenged the widespread use of CT due to concerns regarding long‐term effects from exposure to ionizing radiation (with CT), CT having a high rate of incidental findings that have the potential to create unnecessary follow‐up evaluation, higher cost of CT compared to US, and ease of access to US with more emergency department (ED) physicians obtaining training and certification in point‐of‐care US. Smith‐Bindman et al. performed a multicenter randomized control trial (RCT) to assess the effects of US and CT for suspected nephrolithiasis [9]. Patients who presented to the ED during the daytime (2759) suspected of having nephrolithiasis were randomized to US performed by the ED physician, US performed by a radiologist, or CT. The primary outcome was 30 day incidence of high‐risk diagnoses with complications that could be related to missed or delayed diagnosis. The results demonstrated that incidence of high‐risk diagnoses with complications did not vary significantly between groups, with the overall rate being low at 0.4%. There were also no significant differences in return ED visits or hospitalizations between the groups. Patients in the US groups were more likely than those in the CT group to undergo additional testing during the initial ED visit (40.7% for ED US, 27% for radiology US, and 5.1% for CT); however, mean total costs for the ED visit was lower by $25 for patients assigned to US than to those assigned to CT (P < 0.001). These results suggest that US can be safely used as an initial imaging modality when nephrolithiasis is suspected and leads to a lower overall ED visit cost. This study was not without limitations, especially patient selection prior to randomization. It is also does not address the impact of imaging on subsequent stone treatment or the overall cost of care beyond the ED visit. Thus it is always important to consider clinical context when selecting an imaging study for stones.

Observation with medical expulsive therapy

In the absence of obstruction and under the correct clinical circumstances, it is reasonable to observe a patient for spontaneous stone passage. Lotan et al. created a decision‐tree model in 2002 that showed that if observation did not fail, and no additional financial costs emerged such as ED visits or future surgery, observation was the least costly pathway compared to lithotripsy or ureteroscopy (URS) [10]. However, it is not always easy to predict which patients will pass their stone spontaneously, with studies showing anywhere from 13 to 75% failure of spontaneous passage based on size and location and 17–33% ultimately requiring intervention [11, 12].

The likelihood of spontaneous passage of ureteral calculi depends on ureteral anatomy, stone size, and stone location [11, 13]. Spontaneous passage rates increase the more distal the location of the stone at diagnosis and vary inversely with stone size [13]. Numerous pharmacologic agents have been shown to increase the likelihood of spontaneous passage, thus eliminating the need for surgery or further intervention. These drugs constitute so‐called medical expulsive therapy (MET) [14]. The use of MET became widespread based on small RCTs and meta‐analyses that demonstrated medication use increased stone passage rates at relatively low cost. However, this conclusion was recently called into question. A large, multicenter placebo‐controlled RCT was performed in the United Kingdom in which 1167 patients with ureteral stones ≤10 mm were randomized 1:1:1 to tamsulosin 0.4 mg (alpha‐blocker), nifedipine 30 mg (calcium channel blocker), or placebo to determine the proportion of patients who did not require further intervention for stone clearance within 4 weeks of randomization [15]. The study demonstrated that neither tamsulosin nor nifedipine was effective at decreasing the need for further treatment for patients with expectantly managed ureteral stones at 4 weeks, even after adjusting for factors such as stone size and location (Table 72.1). After further extensive sensitivity analyses of the same data it was demonstrated that MET was not cost‐effective with either drug, owing to the fact that there was no difference in quality‐adjusted life years gained or in cost between the trial groups [16]. Table 72.2 displays these cost data.

Table 72.1 Primary outcome results, no need for intervention at 4 weeks.

Source: [15]. Reproduced with permission of Elsevier.

	Odds ratio (95% CI); P value	Risk difference (95% CI)
MET vs. placebo
Unadjusted	1.04 (0.77–1.43); 0.76	0.8% (−4.1 to 5.7)
Adjusted	1.06 (0.70–1.60); 0.78	0.9% (−5.1 to 6.8)
Tamsulosin vs. nifedipine
Unadjusted	1.07 (0.74–1.53); 0.73	1.0% (−4.6 to 6.6)
Adjusted	1.06 (0.73–1.53); 0.77	0.8% (−4.5 to 6.1)
Tamsulosin vs. placebo
Unadjusted	1.08 (0.76–1.56); 0.76	1.2% (−4.4 to 6.9)
Adjusted	1.09 (0.67–1.78); 0.73	1.3% (−5.7 to 8.3)
Nifedipine vs. placebo
Unadjusted	1.02 (0.71–1.45); 0.93	0.2% (−5.4 to 5.9)
Adjusted	1.03 (0.68–1.56); 0.88	0.5% (−5.6 to 6.5)

CI, confidence interval; MET, medical expulsive therapy.

Unadjusted and adjusted for stone location (lower vs. middle vs. upper ureter), stone size (≤5 vs. >5 mm), and center (random effect).

Table 72.2 Summary of costs.

Source: [16]. Without need for permission by UK Non‐commercial government license for public sector information.

	Intervention {n, mean [median] (SD)}
Resource	Tamsulosin	Nifedipine	Placebo
Intervention	383, £4.96	383, £6.95	384, £0
Analgesics and antibiotics	383, £4 [£5] (2)	383, £4 [£5] (2)	383, £4 [£5] (2)
Diagnostic tests^a	383, £96 [£120] (40)	383, £94 [£120] (36)	383, £98 [£120] (41)
Doctor visits	329, £9 [£0] (30)	331, £8 [£0] (30)	325, £6 [£0] (24)
Nurse visits	329, £0.57 [£0] (5)	330, £0.28 [£0] (2)	325, £1.14 [£0] (14)
Outpatient visits^b	377, £73 [£101] (74)	378, £64 [£101] (67)	379, £67 [£101] (70)
All interventions^c	378, £250 [£0] (581)	379, £267 [£0] (608)	379, £291 [£0] (632)
Excess admission days^d	375, £44 [£0] (169)	377, £62 [£0] (279)	375, £65 [£0] (298)
Total costs^e	325, £326 [£228] (494)	329, £335 [£227] (557)	323, £367 [£223] (619)

^a Includes tests conducted at baseline, 4 weeks and participant‐reported tests.

^b Includes 4 week clinic attendance and participant‐reported outpatient visits.

^c Cost of all interventions as some participants had more than one intervention in a visit.

^d Consists of duration of admissions reported in the Case Report Form minus the median 1 day admission (urology department) as well as participant admissions.

^e Estimates based on participants with complete cost data.

Since the primary outcome of the UK multicenter RCT was no need for additional intervention at 4 weeks as opposed to radiographic evidence of stone passage, MET continues to be used to aid passage of distal ureteral stones. Outside of this indication its use has largely fallen out of favor.

Immediate decompression

If ureteral obstruction is present and infection is suspected/present, immediate decompression of the collecting system is paramount. The two options for decompression include internal ureteral stent placement or percutaneous nephrostomy. Two RCTs have addressed the choice of optimal modality to treat infection in the setting of ureteral obstruction. Pearle et al. randomized 42 patients with suspected infection and obstruction to either ureteral stent or percutaneous nephrostomy, and compared cost and time to clinical improvement [17]. The two modalities were found to be equally effective with respect to the time to normalization of white blood count and/or patient temperature; however, percutaneous nephrostomy was less costly ($1137 vs. $2401, respectively) due to stent placement being performed under general anesthesia. Mokhmalji et al. randomized 40 patients with hydronephrosis due to ureteral calculi both with and without signs of infection to either receive stenting or nephrostomy [18]. The authors concluded that percutaneous nephrostomy was the superior method of decompression due to shorter antibiotic treatment duration (0 vs. 64% requiring antibiotics for longer than 5 days, respectively), reduced time to definitive stone treatment (25 vs. 50% with need for diversion at 2 weeks, respectively), and need for less fluoroscopy (10 vs. 40% with >2 min, respectively). Cost was not evaluated in the later study.

In general, percutaneous nephrostomy is highly successful in the setting of hydronephrosis due to the large, dilated collecting system. Failed stent placement due to complete ureteral obstruction, which has been reported to occur in up to 20% of cases, is a definite cost concern in favor of nephrostomy as stent failures will incur the additional cost of salvage [18]; however, currently there are no data comparing costs that take into account failed stent placement.

Presuming equal efficacy for decompression in the acute setting of infection and obstruction, the choice of stent placement versus nephrostomy is commonly based on factors other than cost, such as availability of the interventional radiologist versus the operating room, stone size and/or location, physician, and patient preference.

Surgical intervention

Surgical intervention must be considered for stones that are unlikely to or have failed to pass based on aforementioned patient and stone characteristics. The mainstays of treatment for ureteral stones are URS and shock‐wave lithotripsy (SWL). The 2016 American Urological Association (AUA)/Endourological Society Surgical Management of Stones Guideline [19] states that URS should be offered as first‐line therapy for patients with mid or distal ureteral stones who require intervention (those who are not candidates for or who fail MET), as URS is associated with significantly higher stone‐free rates in a single procedure than SWL in this setting. Studies comparing URS versus SWL for distal ureteral stones reported the overall success rate for distal ureteral stones to be approximately 92% for URS (2539/2751) compared to 65% for SWL (2260/3488; P < 0.001) [20]. SWL is an acceptable alternative for patients who decline URS as it has lesser morbidity and a lower complication rate. The disparity in stone‐free rate was greater for mid and distal ureteral stones than proximal ureteral stones, hence the delineation in the guideline.

Costs for URS and SWL differ in great part due to differences in complication rates, stone‐free rates, and equipment costs between the two procedures. Furthermore, factors other than cost influence surgical treatment choice, including patient preference, surgeon skill, stone characteristics, and equipment availability. While numerous studies have been performed to assess cost of URS versus SWL, they are plagued by overuse of charge data rather than cost data, lack of uniform inclusion of costs of preoperative evaluation, costs of disposables or other equipment, cost of lost work productivity, and charges associated with complications.

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