Economic and Utilization Analysis of Robot-Assisted Versus Laparoscopic Live Donor Nephrectomy

Abstract

Background:

Reports of robot-assisted live donor nephrectomies (LDNs) have been emerging in the literature. We sought to examine the national incidence of robot-assisted LDNs and to assess regional use and economic differences in robot-assisted versus laparoscopic LDN.

Methods:

Data from the Nationwide Inpatient Sample (NIS) were used to identify patients who underwent either laparoscopic or robot-assisted LDN between 2009 and 2011. Descriptive analysis was performed to examine differences between the laparoscopic and robot-assisted groups.

Results:

A total of 4,163 cases of LDN were performed using robot-assistance or pure laparoscopic surgery between 2009 and 2011. Of these, 142 were classified as robot-assisted nephrectomies; these cases were all from the western United States. There was no difference in the incidence of complications between the laparoscopic and robot-assisted groups (P=0.206). Median (interquartile range [IQR]) total charges for robot-assisted LDN were $48,639 ($42,380–$53,050) vs $37,019 ($28,715–$48,816) for laparoscopic cases (P<0.001).

Conclusions:

The role of robotic assistance in LDN remains to be determined; we identified no benefits to robotic assistance in our study.

Introduction

Each year an estimated 28,000 kidney transplants are performed in the United States; 21% of these are performed using live donor kidneys, while the remainder are from cadaveric sources.¹ Live donor nephrectomies (LDNs) are preferred to cadaveric nephrectomies due to improved graft survival, and they offer an important means of decreasing the waiting list.^2,3 Furthermore, cost analyses have demonstrated a benefit associated with LDN compared with cadaveric donors.^4,5 With over 99,000 individuals on the kidney transplant waiting list,¹ the incidence of LDN is unlikely to decrease in the coming years. Since the institution of laparoscopy in the 1990s its role in LDN has increased, and it is currently considered the standard of care.^6,7

In the past 10 years, robot-assisted procedures have becoming increasingly common among urologic procedures. Studies have shown that robot-assisted procedures compose more than half of many procedures, including prostatectomy, adult pyeloplasty, and partial nephrectomy.^8
–10 While some advocate for the use of robotic assistance primarily in cases that involve reconstruction, there are others who prefer robotic assistance to pure laparoscopy in all settings.¹¹ Since 2002 reports have emerged of LDNs being performed using robotic assistance.^12
–14 Advocates claim shorter warm ischemia time, fewer short-term complications, and medium-term serum creatinine equivalence, although many studies have used open donor nephrectomy as the comparison group.^12

–15 Using a national database, we sought to determine the national incidence of robot-assisted LDNs. As secondary objectives, we aimed to assess regional use and economic differences in robot-assisted versus laparoscopic LDNs.

Patients and Methods

Data source and population

We performed a retrospective cohort analysis of patients using the Nationwide Inpatient Sample (NIS) database, which is made available by the Healthcare Cost and Utilization Project (HCUP) of the Agency for Healthcare Research and Quality.¹⁶ NIS provides an annual 20% capture of in-patient hospitalizations within nongovernment hospitals in the United States. Patient data are collected from 43 states and are considered nationally representative with the additional function of using discharge weights to estimate national incidence.¹⁶ International Classification of Disease version 9 (ICD-9) codes are used to identify procedures and diagnoses coded during the hospitalization.

We identified all patients who underwent LDN (ICD-9 codes V59.4 and 55.51) from the 2009–2011 NIS database patient files. Robotic assistance was identified using ICD-9 code 174.x, and laparoscopic cases were identified by ICD-9 codes 54.21 and 54.51. All other cases were considered open LDNs and excluded from the study. We chose to use patients from 2009 to 2011 because the ICD-9 code for robotic assistance was instituted in the fourth quarter of 2008. All variables included were assessed for completeness. Race and cost were missing in more than 15% of data: As multiple states do not report race to NIS, it is known to be a limiting factor, and cost was missing in the majority of robot-assisted cases. Both of these variables were eliminated from inclusion in the study.

Outcomes and variables

The primary outcome of interest in this study was the method of performing minimally invasive LDN (robot-assisted vs laparoscopic). Variables included in the analysis were categorized into demographic, hospital, and hospitalization variables. Demographic variables included age and sex. Hospital variables included region (Northeast, Midwest, South, and West) and teaching hospital status. Hospitalization variables were primary payer (Medicare, Medicaid, private insurance, and other), length of stay, postoperative in-hospital complications, and total cost and charges. In-patient complications were classified by organ system using ICD-9 codes 996.x–999.x following previously established methods.¹⁷ As the NIS requires at least 10 cases for the purpose of reporting data, median zip code income quartile, race, and cost were eliminated from the presented analysis. Total charges were defined as the charges assigned by the hospital to the primary payer. While we hoped to examine total costs, due to too few robot-assisted donor nephrectomy cases we were unable to present this data.

Statistical analysis

Population discharge weighting was performed using discharge weights and HCUP methodology.¹⁶ Descriptive analysis of categorical and continuous variables was performed using Pearson's chi-square test and the Mann-Whitney test, respectively. All variables included in the final model were determined a priori. Significance was set at P<0.05. All statistical analyses were performed using Stata 12.1 (Stata Corp. LP, College Station, TX). The Indiana University Institutional Review Board provided exempt status for the conduct of this study.

Results

We identified 4,163 cases of LDN that were performed using robotic assistance or pure laparoscopic surgery between 2009 and 2011. Of these, 142 (3.4%) were classified as robot-assisted. As shown in Table 1, there were no differences in age or sex between the groups. All robot-assisted cases occurred in the western region of the United States. There was a difference in the primary payer for robot-assisted versus laparoscopic LDN (P<0.001). All cases of robot-assisted LDN were performed at teaching hospitals, as were 97% of the laparoscopic cases (P=0.373).

Table 1.

Demographic Characteristics of Patients Undergoing Donor Nephrectomy

	Laparoscopic	Robot-assisted
Factor	n (%)	n (%)	p-value^a
Age, mean (SD)	40.8 (12)	44.0 (13)	0.242
Sex (female)	2468 (65)	71 (50)	0.116
Teaching hospital	3885 (96.5)	142 (100)	0.373
Hospital Region
Northeast	829 (21)	0	<0.001
Midwest	1048 (26)	0
South	1353 (34)	0
West	790 (20)	142 (100)
Primary Payer
Medicare	403 (10)	56 (39)	<0.001
Medicaid	155 (4)	0
Private insurance	1839 (47)	0
Other	1485 (38)	86 (61)

Chi-square test for categorical variables; Mann-Whitney test for continuous variables.

Complications in the laparoscopic LDN patients were uncommon, occurring in 5% of patients compared with no identified complications in the robot-assisted LDN group (P=0.206). Digestive tract complications, such as postoperative ileus, were the most common among LDN cases, occurring in 2.4% of cases. Other complications occurred in less than 1% of patients and included complications of the urinary tract, respiratory tract, cardiovascular system, and accidental punctures. As shown in Table 2, The median (interquartile range [IQR]) length of hospitalization for robot-assisted cases was 3 days (3–4) compared with 3 days (2–3) for laparoscopic cases (P<0.001). Median (IQR) total charges for robot-assisted LDN were $48,639 ($42,380–$53,050) vs $37,019 ($28,715–$48,816) (P<0.001).

Table 2.

Perioperative Characteristics of Patients Undergoing Donor Nephrectomy

	Laparoscopic	Robot-assisted
Factor	n	n	p-value^a
Length of stay, median (IQR)	3 (Range: 2–3)	3 (Range: 3–4)	<0.001
Complications	214 (5)	0	0.206
Total charges, median (IQR)	$37,019 (Range: 28,715–48,816)	$48,638.5 (Range: 42,380–53,049.5)	<0.001

Chi-square test for categorical variables; Mann-Whitney test for continuous variables.

Interquartile range.

Discussion

Widespread adoption of new technology into surgical techniques should require the demonstration of either operative benefit from the procedure or decreased surgical and hospital costs. Using a nationally representative sample of patients, we compared patients undergoing robot-assisted and laparoscopic LDN to determine differences in robot-assisted technique use, charges, and patient population.

Although we identified no in-hospital complications in the robot-assisted LDN group, there was no statistical difference from the 5% rate of complications observed in the laparoscopic LDN group. Thirty-day complications are rare in LDN.^14,18,19 Historically, rates of major (Clavien Grade III or higher) perioperative complications are accepted at between 3% and 6%, with minor complications observed in up to 22% of laparoscopic LDN cases.²⁰ Perioperative complications observed in robot-assisted LDN cohorts either do not occur or are statistically negligible,^8,14 and no differences have been noted in comparisons with either laparoscopic or open LDN.^13
–15,21 Although evaluating long-term differences in patient outcomes between robot-assisted and laparoscopic LDN remains outside the scope of this study, we found no difference in in-hospital complications. A long-term function study previously showed an average 23% loss of renal function after 11 years in kidney donors,²² and recently Segev and colleagues²³ demonstrated that there is no difference in perioperative morbidity or survival for patients undergoing LDN compared to the general population. Thus, it is reasonable to assume that there is no difference in perioperative morbidity associated with robot-assisted LDN; however, with complications occurring at such low rates it will take even larger cohorts of patients to detect a difference.

With no differences in postoperative morbidity, the question of differences in intraoperative factors must be raised. A recent study from Liu and associates²⁴ compared robot-assisted LDN with laparoscopic LDN for right-sided donor nephrectomy and found no difference in warm ischemia time or operative time between the groups. Estimated glomerular filtration rates were higher in the robot-assisted LDN than laparoscopic, although the reason for this was unclear.²⁴ Renoult and colleagues¹⁴ compared robot-assisted LDN with open LDN and found longer operative and warm ischemia times in the robot-assisted group, although there were no differences in short-term creatinine clearance between the groups. Unfortunately, due to the nature of the data set used for this study we were unable to assess if there were differences in operative or warm ischemia times. Comparisons of robot-assisted LDN to laparoscopic LDN should be encouraged over comparisons with open LDN, however, as laparoscopic LDN is the current preferred modality and is more similar to robot-assisted LDN.

Previous studies have noted longer hospitalization time in the robot-assisted LDN population.²⁴ This increase in hospitalization time directly correlates with an increase in hospital charges. In a study by Hubert and colleagues,¹⁵ robot-assisted LDN patients were hospitalized an average of 5.5 days, which is longer than the average hospitalization times reported for laparoscopic LDN.^25,26 These findings were confirmed in our study, in which longer hospitalizations were noted in the robot-assisted LDN group. The charges assigned to the primary payer for robot-assisted LDN were over $10,000 more than for laparoscopic LDN (P<0.001). It is widely accepted that robot-assisted procedures are associated with significantly higher charges than laparoscopic or open techniques, and this should be considered when deciding whether to use robotic assistance.^24,27 Many have argued that reduced hospitalization time, fewer complications, and quicker return to work should offset these costs.^8,9,28 Improved postoperative cosmesis could be another significant advantage for laparoscopic LDN compared to robot-assisted LDN. During laparoscopic LDN, 3- and 5-mm ports can be used, and one of them can be positioned in a less visible part of the abdomen (lower abdomen). Comparatively, 8-mm ports are normally used during robot-assisted LDN. At this juncture, robotic assistance is beneficial for complex reconstruction and intracorporeal suturing, but in a nonreconstructive case such as total nephrectomy it is difficult to justify the increased charges found in this study.

Amid the evolving climate of health care delivery, accountable care organizations (ACO) are becoming increasingly common payers. The Affordable Care Act encourages expansion and use of ACOs in the delivery of care. As a single sum of money is assigned to specific diagnoses, procedures that are not sufficiently shown to provide clinical and economic benefit to the patient will be used less in order to maintain reimbursement to the physician and hospital. This goal of minimizing costs will decide the fate of robotic assistance.^29,30 Based on our findings and previous studies, there is neither a clinical nor an economic benefit to robotic assistance in LDN. In the setting of an adequately trained laparoscopic surgeon, laparoscopic LDN is likely the best option, as it has demonstrated benefits over open LDN. With the development of alternate robotic systems, there is potential in the near future for reductions in the costs associated with robotic assistance, which might result in more widespread use.

An administrative database has many limitations. The quality of the data that we report upon in this study is solely reliant upon the coding and reporting practices of institutions across the country. Additionally, we used ICD-9 codes to identify patient procedures and complications. The limited number of robot-assisted LDN cases reported to the NIS during our study period makes it difficult to draw significant conclusions or recommendations in this study; however, we believe that this study is important in that it is the first nationally representative examination of the use of robot-assisted LDN. It provides an initial charge comparison along with analysis of differences in hospital stay between robot-assisted and laparoscopic LDN. Understanding use of new technology is increasingly important as we move forward in a resource-constrained environment, and the benefits of technology must be demonstrated before its incorporation into mainstream practice.

Conclusion

Robot-assisted LDN cases accounted for 3.4% of the LDNs performed between 2009 and 2011. The use of robotic assistance in donor nephrectomy added approximately $10,000 to the total charge as well as an increase in the length of stay. The claim that robot-assisted LDNs improve the quality of the procedure cannot be supported with the current data. With such low reported rates of complications for LDN, it is difficult to recommend widespread use of robotic assistance for surgeries that do not contain a reconstructive component.

Footnotes

Disclosure Statement

No competing financial interests exist for the authors.

Abbreviations Used

References

Organ Procurement and Transplantation Network (OPTN). U.S. Department of Health and Human Services. Updated 2013. Available at http://optn.transplant.hrsa.gov (Accessed December 2013 ).

Terasaki

, Cecka

, Gjertson

, et al. High survival rates of kidney transplants from spousal and living unrelated donors. N Engl J Med, 1995; 333:333–336.

Davis

, Delmonico

. Living-donor kidney transplantation: A review of the current practices for the live donor. J Am Soc Nephrol, 2005; 16:2098–2110.

Mullins

, Thomas

, Pradel

, et al. The economic impact of laparoscopic living-donor nephrectomy on kidney transplantation. Transplantation, 2003; 75:1505–1512.

Smith

, Woodward

, Cohen

, et al. Cadaveric versus living donor kidney transplantation: A Medicare payment analysis. Transplantation, 2000; 69:311–314.

Alston

, Spaliviero

, Gill

. Laparoscopic donor nephrectomy. Urology, 2005; 65:833–839.

Yuan

, Liu

, Zheng

, et al. The safety and efficacy of laparoscopic donor nephrectomy for renal transplantation: An updated meta-analysis. Transplant Proc, 2013; 45:65–76.

Benway

, Bhayani

, Rogers

, et al. Robot assisted partial nephrectomy versus laparoscopic partial nephrectomy for renal tumors: A multi-institutional analysis of perioperative outcomes. J Urol, 2009; 182:866–872.

, Hevelone

, Lipsitz

, et al. Use, costs and comparative effectiveness of robotic assisted, laparoscopic and open urological surgery. J Urol, 2012; 187:1392–1398.

10.

Monn

, Bahler

, Schneider

, et al. Emerging trends in robotic pyeloplasty for the management of ureteropelvic junction obstruction in adults. J Urol, 2013; 189:1352–1357.

11.

Rozet

, Jaffe

, Braud

, et al. A direct comparison of robotic assisted versus pure laparoscopic radical prostatectomy: A single institution experience. J Urol, 2007; 178:478–482.

12.

Galvani

, Rilo

, Samame

, et al. First fully robotic-assisted total pancreatectomy combined with islet autotransplant for the treatment of chronic pancreatitis: A case report. Pancreas, 2013; 42:1188–1189.

13.

Horgan

, Vanuno

, Sileri

, et al. Robotic-assisted laparoscopic donor nephrectomy for kidney transplantation. Transplantation, 2002; 73:1474–1479.

14.

Renoult

, Hubert

, Ladriere

, et al. Robot-assisted laparoscopic and open live-donor nephrectomy: A comparison of donor morbidity and early renal allograft outcomes. Nephrol Dial Transplant, 2006; 21:472–477.

15.

Hubert

, Renoult

, Mourey

, et al. Complete robotic-assistance during laparoscopic living donor nephrectomies: An evaluation of 38 procedures at a single site. Int J Urol, 2007; 14:986–989.

16.

Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample, 2009–2011. U.S. Department of Health and Human Services, Agency for Healthcare Research and Quality, Rockville, MD. December 2013. Available at www.hcup-us.ahrq.gov/nisoverview.jsp (Accessed: February 26, 2014 ).

17.

Kim

, Boorjian

, Shah

, et al. Contemporary trends of in-hospital complications and mortality for radical cystectomy. BJU Int, 2012; 110:1163–1168.

18.

, Ratner

, Montgomery

, et al. Laparoscopic live donor nephrectomy: Trends in donor and recipient morbidity following 381 consecutive cases. Ann Surg, 2004; 240:358–363.

19.

Schold

, Goldfarb

, Buccini

, et al. Comorbidity burden and perioperative complications for living kidney donors in the United States. Clin J Am Soc Nephrol, 2013; 8:1773–1782.

20.

Lentine

, Patel

. Risks and outcomes of living donation. Adv Chronic Kidney Dis, 2012; 19:220–228.

21.

Gorodner

, Horgan

, Galvani

, et al. Routine left robotic-assisted laparoscopic donor nephrectomy is safe and effective regardless of the presence of vascular anomalies. Transplant Int, 2006; 19:636–640.

22.

Gossmann

, Wilhelm

, Kachel

, et al. Long-term consequences of live kidney donation follow-up in 93% of living kidney donors in a single transplant center. Am J Transplant, 2005; 5:2417–2424.

23.

Segev

, Muzaale

, Caffo

, et al. Perioperative mortality and long-term survival following live kidney donation. JAMA, 2010; 303:959–966.

24.

Liu

, Narins

, Maley

, et al. Robotic-assistance does not enhance standard laparoscopic technique for right-sided donor nephrectomy. JSLS, 2012; 16:202–207.

25.

Kok

, Lind

, Hansson

, et al. Comparison of laparoscopic and mini incision open donor nephrectomy: Single blind, randomised controlled clinical trial. BMJ, 2006; 333:221.

26.

Simforoosh

, Basiri

, Tabibi

, et al. Comparison of laparoscopic and open donor nephrectomy: A randomized controlled trial. BJU Int, 2005; 95:851–855.

27.

Barbash

, Glied

. New technology and health care costs: The case of robot-assisted surgery. N Engl J Med, 2010; 363:701–704.

28.

Dols

, Kok

, Ijzermans

. Live donor nephrectomy: A review of evidence for surgical techniques. Transplant Int, 2010; 23:121–130.

29.

Dall

, Gallo

, Chakrabarti

, et al. An aging population and growing disease burden will require a large and specialized health care workforce by 2025. Health Aff (Millwood), 2013; 32:2013–2020.

30.

Mehta

, Macklis

. Overview of accountable care organizations for oncology specialists. J Oncol Pract, 2013; 9:216–221.