Percutaneous Cryoablation vs Partial Nephrectomy: Cost Comparison of T1a Tumors

Abstract

Purpose:

To compare cost of percutaneous cryoablation vs open and robot-assisted partial nephrectomy of T1a renal masses from the hospital perspective.

Materials and Methods:

We retrospectively compared cost, clinical and tumor data of 37 percutaneous cryoablations to 26 open and 102 robot-assisted partial nephrectomies. Total cost was the sum of direct and indirect cost of procedural and periprocedural variables. Clinical data included demographics, Charlson Comorbidity Index (CCI), hospitalization time, complication rate, ICU admission rate, and 30-day readmission rates. Tumor data included size, RENAL nephrometry score, and malignancy rate. Student's t-test was used for continuous variables and Fisher's exact or chi-square tests for categorical data.

Results:

Mean total cost was lower for percutaneous cryoablation than open or robot-assisted partial nephrectomy: $6067 vs $11392 or $11830 (p<0.0001) with lower cost of procedure room: $1516 vs $3272 or $3254 (p<0.0001), room and board: $95 vs $1907 or $1106 (p<0.0001), anesthesia: $684 vs $1223 or $1468 (p<0.0001), and laboratory/pathology fees: $205 vs $804 or $720 (p<0.0001). Supply and device cost was higher than open: $2596 vs $1352 (p<0.0001), but lower than robot-assisted partial nephrectomy: $3207 (p=0.002). Mean hospitalization times were lower for percutaneous cryoablation (p<0.0001), while age and CCI were higher (p<0.0001). No differences in tumor size, nephrometry score, malignancy rate complication, ICU, or 30-day readmission rates were observed.

Conclusion:

Percutaneous cryoablation can be performed at significantly lower cost than open and robotic partial nephrectomies for similar masses.

Introduction

As economics plays a greater role in healthcare, increasing emphasis is being placed on the cost of therapeutic interventions.^1,2 Critical assessment of cost not only sets the stage for cost saving strategies but also allows for determination of a procedures value, defined as clinical efficacy divided by cost.³ Clinical efficacy can be readily defined in terms of survival or disease-free interval.³ Cost on the other hand is much more complicated, and the complexities of hospital accounting make a true cost determination next to impossible. Central to any cost enumeration process is the perspective from which costs are calculated. From the payers' perspective, costs are reported as charges, that is, the dollar amounts billed to third party payers, which in reality bears little to the true cost of performing a procedure.⁴ Costs from the patient perspective depend on a patient's willingness and ability to pay and have difficulty in translating from the individual to the population level.⁵ The hospital perspective offers the ability to determine the totality of cost through a breakdown of the individual cost elements, while minimizing assumptions,⁶ and can be useful in comparing the cost of competing procedures of the same condition.

Increased utilization of cross-sectional imaging has resulted in higher detection of incidental small renal masses.⁷ Fortunately, the majority are discovered at an early stage and is amenable to curative intervention via open partial nephrectomy, robot-assisted laparoscopic partial nephrectomy, or percutaneous cryoablation.^8,9 Considering the comparable efficacy rates between these procedures,¹⁰ attention now turns to comparing their actual costs as a preliminary step in determining the treatment option of greatest value. The goal of this study was to compare the actual cost of percutaneous cryoablation to open partial nephrectomy and robot-assisted partial nephrectomy from the hospital's perspective.

Materials and Methods

Patient selection and procedure details

Following approval by the institutional review board, cost data of all consecutive renal tumors treated by percutaneous cryoablation, open partial nephrectomy, or robot-assisted partial nephrectomy at our institution from January 2011 to March 2013 were compiled into a HIPPA compliant database. Patients younger than 18 years or those who underwent multiple surgical procedures during the same encounter (e.g., open partial nephrectomy and cholecystectomy) were excluded. Similarly, all tumors >4 cm in maximum dimension were excluded. A total of 37 percutaneous cryoablations in 34 patients (mean age of 69.1 years, 73% male), 26 open partial nephrectomies in 26 patients (mean age 61.2 years, 69% male), and 102 partial nephrectomies in 100 patients (mean age 59 years, 68% male) were included. To assess for heterogeneity in patient and tumor characteristics, we also included clinical and tumor data as detailed below.

Cost data

The total cost of each procedure was calculated as the sum of direct and indirect costs to the hospital for each of the following procedural and periprocedural variables:

• Procedure/Operating Room—included the cost of occupation, maintenance, and depreciation of a surgical suite or the CT intervention suite. This also included the cost of support personnel such as circulating nurse, surgical technologist, or radiology technologist during each procedure.

• Supplies and devices—included cost of the cryoprobes, surgical utensils, and disposable instruments (towels, gloves etc). Amortized cost of the Davinci robot was included in the direct cost of this variable, while the depreciation cost was foiled into the indirect cost.

• Imaging—this included operating, maintenance, and depreciation costs of the CT scanner during percutaneous cryoablation or intraoperative ultrasound during partial nephrectomy. This also included obtaining and interpretation of additional imaging (such as a chest X-ray) during each postprocedure course.

• Anesthesia fees- included cost of anesthesia unit setup, anesthetic and medications rendered, and anesthetist time during each procedure.

• Recovery room—billed as a function of time spent in the PACU.

• Routine room and board—included the cost of occupying a regular hospital bed, care products, and nursing/nurse's aid time.

• ICU room and board—costs associated with occupation of an intensive care unit bed with advanced hemodynamic monitoring devices such as central venous pressure monitoring.

• Respiratory care—this included time of respiratory care therapist and utilization of respiratory support devices such as a nebulizer.

• Laboratory and pathology fees—included the cost of fixation, staining, and interpretation of specimens obtained by surgical enucleation. This also included the cost of phlebotomy and processing of serum specimens such as complete blood count.

• Pharmacy—was the cost of intravenous fluids and all medications administered during periprocedural course.

• Other costs—determined as the cost of materials and/or personnel time associated with physical therapy, occupational therapy, speech therapy, dialysis, ECG, echocardiography, and blood transfusion.

Clinical data

Clinical variables included patient age, sex, and body mass index (BMI), intensive care unit (ICU) admission rate, and emergency room visitation/hospital readmission rates within 30 days of each procedure. We reassessed comorbidities by calculating the Charlson Comorbidity Index score (CCI) for each patient.¹³ Hospital length of stay was calculated from the time of admission to the time of discharge. Complications were reported as major or minor in accordance with standard guidelines set by the Society of Interventional Radiology.¹⁴

Tumor data

Tumor size and R.E.N.A.L. nephrometry scores were calculated by retrospective review of each patient's preprocedural cross-sectional imaging, (contrast-enhanced CT or MRI).¹⁵ The mean R.E.N.A.L. nephrometry score was calculated as the mean of numerical values, including the radius in centimeters (R), endophytic/exophytic extent (E), nearness to the hilum (N), and location relative to polar lines (L). The anterior/posterior (A) measurement, reported as a letter value, was not included in the calculation. The malignancy rate was calculated based on the histology of each tumor biopsy or from enucleated specimens in operative cases that proceeded without biopsy. Malignant lesions included clear-cell carcinoma, papillary cell carcinoma, chromophobe, and renal-cell carcinoma (RCC) unspecified (such as sarcomatoid). Oncocytomas, angiomyolipomas, and mulitloculated cysts were counted as benign. Indeterminate lesions were not considered in the malignancy rate.

Percutaneous cryoablation procedure details

All percutaneous cryoablations were performed under computed tomography (CT) guidance using a 16-slice SOMATOM^® scanner (Siemens^®, Erlangen, Germany) in a nondedicated CT intervention suite. General anesthesia and the Visual-ICE^® Cryoablation system (Galil Medical^®, St. Paul, MN) were used in all cases. Hydrodissection was used to buffer tumors in close proximity with other viscera.¹⁶ The number of cryoprobes was based on the three-dimension tumor size positioned to obtain an 8–10 mm ablation margin (Fig. 1). All ablations consisted of at least two freeze–thaw cycles followed by a contrast-enhanced CT to determine the adequacy of the ablation as indicated by the hypodense ice ball. Standard postprocedure care included monitoring in a standard postanesthesia care unit (PACU) followed by monitoring for a maximum of 23 hours. Here patients received IV hydration, patient-controlled analgesia, antinausea medication, and necessary home medications. Patients unfit for discharge were admitted to a routine hospital bed or intensive care unit as indicated.

FIG. 1.

Axial computed tomography image shows a percutaneous cryoablation probe with a surrounding hypodense ablation cavity.

Partial nephrectomy procedure details

Both open and robot-assisted partial nephrectomies were performed under general anesthesia in a standard surgical suite. The use of mannitol, intraoperative ultrasound, and Surgicel^® Bolster (Ethicon, Somerville, NJ) was at the surgeons' discretion. For the open partial nephrectomy, ice slurry was used to cool the kidney and facilitate enucleation of the mass that was sent in its entirety for pathologic evaluation. Robot-assisted partial nephrectomy was performed using the Davinci^® robot system (Intuitive Surgical^®, Sunnyville, CA) employed with either two or three arm ports plus an assistant port. All open and robot-assisted partial nephrectomy patients were monitored in a PACU before being admitted to a regular surgical floor or intensive care unit. During admission, patients received necessary home medications in addition to as-needed postoperative medications and support devices.

Biopsy and follow-up

By imaging alone, any solid enhancing renal tumor is considered malignant until proven otherwise. With improvement in tissue diagnosis, percutaneous sampling has become standard practice for any lesion being considered for percutaneous cryoablation unless there is a compelling indication otherwise (family history of recurrent tumor, prior biopsy-proven malignancy, anticoagulation). For tumors being evaluated by partial nephrectomy, tissue sampling is at the discretion of the treating surgeon. Because of the wide variability in rates of tissue sampling (CT or US-guided biopsy), it was not included in the total cost, whether it was performed at a prior encounter or immediately before percutaneous cryoablation, as was the case early in our experience.

Surveillance following partial nephrectomy and/or percutaneous cryoablation is variable depending on patient condition, tumor margins, or risk factors (e.g., family history). In general, dual-phase CT is routinely performed at 6 months following partial nephrectomy with repeat CT or magnetic resonance imaging (MRI) on a yearly basis with periodic renal ultrasound. A chest X-ray is obtained every year for the first 5 years postoperatively. Following percutaneous cryoablation, dual-phase CT or MRI is obtained at 6, 12, and 24 months postablation. Because of the wide variability in follow-up protocols, patient compliance, and imaging (ultrasound, CT, or MRI), these costs were not included.

Direct cost refers to the dollar amount incurred by the hospital for each procedural and periprocedural cost variable.¹¹ Indirect cost is the dollar amount added to each direct cost from nonpatient care departments such as financing, human resources, housekeeping, office supplies, and utilities.

Financial data for each procedure were obtained from our finance department using the EPSi database (Allscripts^®, Chicago, IL). All finances were reported in 2011 US dollar amounts. Because of the relatively short time frame (27 months), the rate of inflation (∼3%) did not appear to significantly affect data¹² and was not adjusted for within this dataset.

Statistical analysis

Total costs as well as the cost of each individual procedural and periprocedural variable (sum of direct and indirect cost of each variable), clinical variables (age, gender, BMI, CCI, length of stay, ICU admission rate, 30-day readmission rate, major/minor complication rate), and tumor variables (tumor size, mean R.E.N.A.L nephrometry score, malignancy rate) were compared. First, we compared percutaneous cryoablation vs open partial nephrectomy and then percutaneous cryoablation vs robot-assisted partial nephrectomy. Student's t-test was used for continuous variables and Fisher's exact or chi-square tests for categorical data. Statistical significance was concluded when a two-tailed p-value was <0.05.Statistical analysis was conducted using SPSS (IBM^®, Armonk, NY).

Results

Patient and clinical data

Percutaneous cryoablation patients were older (mean 69.1 years, range 51–85) than patients who underwent open partial nephrectomy (mean 61.2 years, range 48–78, p<0.0001) or robot-assisted partial nephrectomy (mean age 59 years, range 30–85, p<0.0001). Comorbidity indices were also higher for percutaneous cryoablation patients (CCI=7.14, standard deviation±1.398) compared to 5.0±1.020 for open partial nephrectomy (p<0.0001) or robot-assisted partial nephrectomy 4.98±1.335 (p<0.0001). No differences in gender; 73% male for percutaneous cryoablation vs 69% (p=0.931) for open partial nephrectomy and 68% (p=0.222) for robot-assisted partial nephrectomy. BMI: mean 30.4, range 17.4–53.3 for percutaneous cryoablation, vs 29.0, range 19.3–43.1 (p=0.748) for open partial nephrectomy or 29.1, range 15.0–46.8 (p=0.476) for robot-assisted partial nephrectomy were observed. Of the patients who underwent percutaneous cryoablation, 4 had contralateral nephrectomies and 6 had at least one prior partial nephrectomy; one of which was a residual/recurrence after robot-assisted partial nephrectomy. One patient underwent percutaneous ablation of an incompletely ablated robot-assisted laparoscopic cryoablation. Two patients had familial RCC syndromes and 1 patient had a history of Birt-Hogg-Dubé. Two patients who underwent robot-assisted partial nephrectomy had remote contralateral partial nephrectomies.

Nearly 90% (33/37) of patients who underwent percutaneous cryoablation were discharged within 24 hours of their procedure. Four patients (10.8%) required hospitalization between 1–5 days with no patients requiring admission for >5 days. Open partial nephrectomy patients were routinely hospitalized postoperatively with 81% of patients (22/27) admitted for 1–5 days, while 5 patients (18.5%) required >5 days. Of patients who underwent robot-assisted partial nephrectomy, 4 patients (∼4%) were discharged within 1 day, 92% (94/102) required 1–5 days admission, and 4 patients (4%) were admitted for >5 days. Mean hospitalization time for percutaneous cryoablation was 1.08 days, standard deviation 0.752, significantly lower than open partial nephrectomy: mean 4.53 days, standard deviation 1.60 (p<0.0001) and robot-assisted partial nephrectomy: mean 2.60 days, standard deviation 1.40 (p<0.0001).

Of the patients who underwent percutaneous cryoablation, 3 had minor and one had a major complication. Two of the minor complications were overnight admission for pain control. The third minor complication was in a patient with preprocedural end-stage renal disease who was noted to have acutely elevated serum potassium that resolved following a single session of hemodialysis. The major complication was a perinephric hematoma following ablation of a 4 cm endophytic mass abutting the hilar vessels. Following coil embolization of the bleeding vessel, the patient was admitted to the ICU for hemodialysis.

Three patients in the open partial nephrectomy group had major complications. One required operative ligation of a urine leak. Another patient, with a history of contralateral total nephrectomy, had low urine output over his postoperative course that resolved spontaneously during monitoring in the ICU. A third patient required placement of ureteral stents for hydronephrosis. A minor complication was seen in a patient with a history of COPD, who required prolonged intubation (−46 hours), but was eventually extubated without incident. Three major complications were noted in the robotic group. Two patients developed postoperative arrhythmias requiring ICU monitoring and cardioversion. A different patient became hypotensive during PACU monitoring and was found to have a perinephric hematoma and had the bleeding vessel effectively embolized by Interventional Radiology. There was one minor complication of a patient with a history of COPD, who was noted to be hypoxic and required brief ICU monitoring, but did not require intubation. Statistically, there were no differences in the complication rate of percutaneous cryoablation n=4 vs open partial nephrectomy n=4 (p=0.0235) or vs robotic partial nephrectomy n=5 (p=0.348). No difference in the rate of ICU admission between percutaneous cryoablation n=2 and open partial nephrectomy n=2 (p=0.172) or robot-assisted partial nephrectomy n=4 (p=0.434) was observed.

In the cryoablation group, one patient was seen at postoperative day 1 for incisional pain. Another patient, with a history of Birt–Hogh–Dubé, was seen on postprocedure day 22 for a recurrent pneumothorax that resolved with monitoring. One patient in the open group was seen on postoperative day 6 for diarrhea and was found to have clostridium difficile colitis. Another patient was seen on postoperative day 21 for pneumonia. One patient who had a robotic partial nephrectomy was seen for hydronephrosis postoperative day 4. He was subsequently discharged following overnight admission and endoscopic stent placement.

With a mean follow-up time of 22.1 months, one patient with a history of familial RCC who underwent percutaneous cryoablation was found to have an enhancing focus suspicion for disease recurrence at the margin of an ablation cavity. Whether this was a failed ablation or a new lesion adjacent to the ablation cavity is debatable. Nonetheless, this patient underwent repeat ablation, and at the latest, follow-up (6.2 months) was found to have no recurrent disease. Recurrence rates in patients undergoing surgical extirpation were excellent. One patient who underwent partial nephrectomy was found to have a 1.0 cm focus of enhancement consistent with incomplete resection. The residual tumor subsequently underwent effective percutaneous cryoablation. At a median follow-up of 28.1 months, none of the patients who underwent open partial nephrectomy was found to have residual disease. Because of the extremely low recurrence rates within all groups, no reasonable statistics could be deduced.

Tumor data

Mean size of tumors that underwent percutaneous cryoablation was 2.11 cm, range 1–4 cm, which was not significantly different from those that underwent open partial nephrectomy: 2.59 cm, range: 1.2–4 (p=0.099) or robot-assisted partial nephrectomy: mean 2.32 cm, range: 1.1–4 (p=0.0055). There was no significant difference in the Mean R.E.N.A.L. nephrometry scores of tumors undergoing percutaneous cryoablation: mean score: 6.48 compared to those that underwent open partial nephrectomy: 6.34 (p=0.841) or robot-assisted partial nephrectomy: 5.67 (p=0.087).

Of the 37 tumors that underwent percutaneous cryoablation, 34 were malignant. Fourteen underwent CT-guided biopsy (10 clear cell, 2 papillary, and 2 chromophobe) and 14 tumors underwent ultrasound-guided biopsy before ablation (9 clear cell, 4 papillary, 1 atypical RCC unclassified). Nine lesions did not undergo tissue sampling: 4 in patients with familial RCC syndromes and presumed to be malignant, one in a patient who had underwent incomplete resection of a clear-cell carcinoma by robotic nephrectomy, and another that had underwent incomplete robot-assisted laparoscopic cryoablation of a papillary carcinoma. Three lesions that underwent CT-guided biopsy immediately before cryoablation were found to be oncocytomas. In the open partial nephrectomy group, 25 tumors were malignant and 1 was benign. Pathology of the 18 enucleated specimens that did not have tissue sampling before resection revealed the following: 8 clear-cell carcinomas, 6 papillary cells, 1 chromophobe, 2 multicystic RCC, and 1 multilocular cyst. Four tumors had CT-guided biopsy before resection included 2 clear-cell and 2 papillary cell carcinomas. Another four had a prior ultrasound-guided biopsy: 3 clear-cell and 1 papillary cell carcinoma. One tumor had an ultrasound-guided biopsy that was nondiagnostic, followed by a CT-guided biopsy showing papillary cell carcinoma. Of the tumors that underwent robot-assisted partial nephrectomy, 85 tumors were malignant, 15 were benign, and 2 were nondiagnostic. Surgical resection without a prior biopsy was performed in 82 tumors that showed 39 clear-cell carcinomas, 20 papillaries, 3 chromophobes, 3 multilocular RCC, 1 angiomyolipoma, 9 oncocytomas, 5 multilocular cysts, and 2 were nondiagnostic. Six tumors had prior CT-guided biopsy: 2 clear cell, 3 papillary, and 1 chromophobe. This included one tumor that had underwent CT-guided biopsy twice; the first sample being nondiagnostic with the second sample demonstrating papillary cell carcinoma. Fourteen had a US-guided biopsy before resection: 6 clear cell, 7 papillary, and 1 unclassified RCC. No significant difference in the rate of malignancy was observed between percutaneous cryoablation n=34 vs open partial nephrectomy n=26 (p=0.897) or robot-assisted partial nephrectomy n=85 (p=0.0693).

Cost data

Detailed cost data are provided in Table 1. When comparing percutaneous cryoablation to open partial nephrectomy, percutaneous cryoablation demonstrated lower mean differences in the following variables: total cost: $4999 (p<0.0001); procedure/operating room: $1723 (p<0.001); routine room and board: $1812 (p<0.0001); anesthesia: $531 (p<0.001); pharmacy: $207 (p=0.014); and laboratory/pathology fees: $600 (p<0.0001). Open partial nephrectomy had a significantly higher supply and device cost: mean difference $1327 (p<0.0001). No difference was observed in the mean difference in cost of the following: imaging: $12 (p=0.875), recovery room: $61 (p=0.391), ICU room and board: $66 (p=0.737), respiratory care: $39 (p=0.267), or other charges: $80 (p=0.629).

Table 1.

Summary Cost Data of Percutaneous Cryoablation vs Open Partial Nephrectomy and Robot-Assisted Partial Nephrectomy

Variable	Median	Mean	Standard deviation	Statistics
Surgical supplies and devices
Cryoablation	$2596	$2772	$550	Cryoablation vs open: p<0.0001
Open	$1352	$1445	$630	Cryoablation vs robot: p=0.002
Robot	$3207	$3288	$1417
Operating room
Cryoablation	$1516	$1770	$1864	Cryoablation vs open: p≤0.0001
Open	$3272	$3494	$700	Cryoablation vs robot: p<0.0001
Robot	$3254	$3280	$707
Imaging
Cryoablation	$0	$179	$366	Cryoablation vs open: p=0.861
Open	$76	$167	$189	Cryoablation vs robot: p=0.390
Robot	$103	$283	$700
Recovery room
Cryoablation	$291	$454	$337	Cryoablation vs open: p=0.331
Open	$410	$393	$139	Cryoablation vs robot: p=0.720
Robot	$356	$432	$227
R&B—Routine
Cryoablation	$0	$95	$278	Cryoablation vs open: p<0.0001
Open	$1694	$1907	$821	Cryoablation vs robot: p<0.0001
Robot	$869	$1106	$674
R&B—ICU
Cryoablation	$0	$133	$814	Cryoablation vs open: p<0.730
Open	$0	$200	$699	Cryoablation vs robot: p<0.914
Robot	$0	$151	$853
Anesthesia
Cryoablation	$684	$653	$281	Cryoablation vs open: p<0.0001
Open	$1,223	$1,184	$375	Cryoablation vs robot: p<0.0001
Robot	$1468	$1,678	$967
Respiratory
Cryoablation	$0	$8	$53	Cryoablation vs open: p=0.267
Open	$0	$47	$168	Cryoablation vs robot: p=0.325
Robot	$0	$57	$488
Medications
Cryoablation	$319	$365	$222	Cryoablation vs open: p=0.014
Open	$485	$572	$362	Cryoablation vs robot: p=0.936
Robot	$315	$368	$184
Laboratory/Pathology
Cryoablation	$80	$205	$299	Cryoablation vs open: p<0.0001
Open	$574	$804	$540	Cryoablation vs robot: p<0.0001
Robot	$485	$720	$656
Other
Cryoablation	$0	$164	$815	Cryoablation vs open: p=0.573
Open	$0	$84	$213	Cryoablation vs robot: p=0.457
Robot	$0	$61	$295
Total
Cryoablation	$6067	$6803	$4459	Cryoablation vs open: p<0.0001
Open	$11,392	$11,803	$3190	Cryoablation vs robot: p<0.0001
Robot	$11,830	$13,242	$4,371

ICU=intensive care unit.

When comparing percutaneous cryoablation to robot-assisted partial nephrectomy, percutaneous cryoablation had significantly lower mean differences in the following: total cost: $6439 (p<0.0001); procedure/operating room: $1510 (p<0.0001); supply and device cost: $515 (p=0.033); routine room and board: $1010 (p<0.0001); anesthesia: $1025 (p<0.0001); laboratory/pathology fees: $615 (p<0.0001). No significant differences were seen in the mean difference in cost of the following: imaging: $104 (p=0.259); pharmacy: $37(p=0.936); recovery room: $21 (p=0.667); ICU room and board: $17 (p=0.914); respiratory care: $49 (p=0.325); or other costs: $7(p=0.4673).

Discussion

Results of the current study show that, from the hospital perspective, percutaneous cryoablation can be performed for approximately $5000 less than open partial nephrectomy and over $6400 less than robot-assisted laparoscopic partial nephrectomy for tumors of similar size, complexity, and malignancy rate. Despite percutaneous cryoablation being performed in older patients with higher comorbidity indices, percutaneous cryoablation had lower hospitalization times and eliminated the cost of many hospital-related expenses such as room and board. Procedure-related costs of percutaneous cryoablation were lower in some aspects, as the use of image guidance avoided the need for a traditional surgical suite, and thus incurred lower cost associated with the procedure room and anesthesia. Supply and device costs of percutaneous cryoablation were higher than open partial nephrectomy, presumably due to the high cost of the cryoprobes.¹⁷ In contrast, supply and device costs were lower than robot-assisted partial nephrectomy, likely due to the high operating fees associated with the robotic device.^18,19 Both open and robot-assisted partial nephrectomies incurred higher laboratory and pathology expenses associated with pathologic evaluation of the enucleated specimen. This, however, can be seen as an advantage of extirpative techniques providing a more definitive pathologic diagnosis compared to core biopsy.²⁰ Findings were observed without sacrificing patient safety as the procedures demonstrated a similar complication rate, ICU admission rate, and 30-day readmission rates.

Previously, the higher recurrence rate with percutaneous cryoablation was thought to offset its long-term cost savings by indicating repeat treatments.^21
–23 Such conclusions are less likely to affect cost data considering that updated efficacy studies have demonstrated recurrence rates of percutaneous cryoablation similar to traditional surgical techniques.^10,24

–27 Of the tumors treated in the current study, one tumor that underwent percutaneous cryoablation had required repeat ablation. That patient had a history familial RCC and whether that was a true recurrence or a new tumor in the renal parenchyma at the ablation margin was debatable. No tumors treated by open or robot-assisted partial nephrectomy underwent repeat surgical treatment; however, a residual tumor (measuring approximately 1 cm) from one robot-assisted partial nephrectomy was a tumor that underwent percutaneous cryoablation. In future studies, long-term efficacy data should be compared to the continuum of care costs to make a true value-based comparison.

The primary goal of this project was to provide updated cost data for future cost effectiveness studies aimed at determining the treatment modality of greatest value from a societal perspective. Cost effectiveness studies to date were either based on surveyed financial data²¹ or excluded important cost variables such as laboratory fees,¹⁷ which demonstrated significant differences in the current study. To minimize the number of assumptions that go into cost effectiveness studies, baseline cost data should be based on actual cost data, which include the totality of procedure and periprocedural cost while limiting estimations, as was demonstrated in the current study. In addition, critical examination of cost sets the stage for cost saving strategies by allowing for evaluation of the individual cost elements and emphasizes the increasing importance of cost containment in the modern era.²⁸

The biggest limitation to this study was inherent to the cost enumeration process. Numerous methods of determining cost have been described, each with their own set of limitations. Utilizing charges as a surrogate for cost is a simplified method of readily available Medicare or Medicaid data, but in reality bares little to the true cost of a procedure.⁴ Cost accounting depends heavily on the volume and buying power of a specific department and also relies on presumptions of labor time, overhead and equipment depreciation, and could potentially exclude significant elements in calculating total treatment cost.²⁹ The current cost analysis was based on the hospital perspective of a single midwest teaching hospital. Although this limits its generalizability, it provides a practical method for comparison of the individual procedures by controlling for some institution-specific variables. For example, the differences in room and board cost should be due to the incidence of admission incurred by either procedure, while the cost associated with anesthesia would be due to differences in the time, amount of anesthetic, and utensils utilized for each procedure rather than the hospital contract with the anesthetic supply company.

Other limitations of the study included its retrospective nature. Physician fees were not included and because of the wide variability in follow-up regiments for the different treatment options, those costs were not included. An additional treatment consideration of small renal masses, which was not included, is the use of active surveillance. Considering patient anxiety and surveillance imaging costs⁷ and risk of progression to metastasis,³⁰ the exact indications for active surveillance remain uncertain.⁹ Nonetheless, future cost and cost effectiveness analysis should also include mention of active surveillance.

Conclusion

The treatment option for any condition depends on a multitude of factors. In the changing face of healthcare, greater emphasis will be placed on the value of different procedures for the same condition. The current study suggests the cost advantage of percutaneous cryoablation over partial nephrectomy and sets the stage for more updated cost effectiveness studies and value determination. With the growing number of cost-related research, healthcare providers should be aware of the methodology associated with and cost studies such as this may help clarify this process.

Footnotes

Acknowledgments

Special thanks to Paulina Ivanova, Michael Weisser, and Dr. Miron Stano for their help and guidance on this Project.

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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