Marchese, Pelletier - 27 - References i Gupta et al., BJU International 105 (2009): 980-83. ii Web. 21 Apr. 2010. iii "Robotic Prostatectomy: Is It the Future?" Web. < v Matthew F. Bultitude, Declan Murphy, Ben Challacombe, Oussama Elhage, Mohammed S. Khan, Qing Wang, Prokar Dasgupta, PATIENT PERCEPTION OF ROBOTIC UROLOGY SO: BJU International VL: 103 NO: 3 PG: 285-286 YR: 2009 CP: © 2008 THE AUTHORS. JOURNAL COMPILATION © 2008 BJU INTERNATIONAL ON: 1464-410X PN: 1464-4096 AD: Health Economics, Guys and St. Thomas Hospital NHS Foundation Trust and Kings College London School of Medicine, London, UK DOI: 10.1111/j.1464-410X.2008.08058.x http://dx.doi.org/10.1111/j.1464- 410X.2008.08058.x vi Charles D. Scales Jr, Peter J. Jones, Eric L. Eisenstein, Glenn M. Preminger, David M. Albala, Local Cost Structures and the Economics of Robot Assisted Radical Prostatectomy, The Journal of Urology, Volume 174, Issue 6, December 2005, Pages 2323-2329, ISSN 0022-5347, DOI: 10.1097/01.ju.0000181830.43340.e7. http://www.sciencedirect.com/science/article/B7XMT-4HW762W-3S/2/e2cf4de356c6958ff0fa4a1acb8d10f9 vii John P. Lenihan Jr., Carol Kovanda, Usha Seshadri-Kreaden, What is the Learning Curve for Robotic Assisted Gynecologic Surgery?, Journal of Minimally Invasive Gynecology, Volume 15, Issue 5, September-October 2008, Pages 589-594, ISSN 1553-4650, DOI: 10.1016/j.jmig.2008.06.015. viii "Intuitive Surgical - Hospital & Surgeon Locator." Web. 12 Jan. 2010. . ixSurveyMonkey: Free online survey software & questionnaire tool. Web. 12 J Background Some surgeons use robotic assistance to achieve dexterity and visualization that would be impossible through other approaches. Although use of robotic-assisted surgery has increased in the United States, the degree of use in ambulatory surgery settings is unknown. Objective To assess how the proportion of outpatient procedures with robotic assistance differs across procedure and facility types, and patient populations. Study Design In this cross-sectional study, we analyzed ambulatory surgery visits involving 12 procedures using data on hospital-owned facilities in 26 states from the 2016 Healthcare Cost and Utilization Project State Ambulatory Surgery and Services Databases. We compared robotic procedures with nonrobotic laparoscopic and nonlaparoscopic procedures. Measures We examined how the proportion of procedures performed robotically differed by expected payer, residence location, community-level income, census region, hospital ownership, and teaching status. Results The proportion of ambulatory procedures with robotic assistance was highest for pyeloplasty (15.1% of 1,903 procedures), myomectomy (14.7% of 14,069), and hysterectomy (10.1% of 301,251). The proportion of visits with robotic assistance was higher for patients with private insurance (4.1%) than for those with other types of insurance (1.9-2.5%; P<.001), higher in private for-profit hospitals (6.2%) compared with nonprofit (3.0%) and public (1.1%) hospitals (P><.001), and higher in nonteaching versus teaching hospitals (4.3% vs. 1.7%; P><.001). Conclusions Robotic-assisted surgery remains relatively uncommon in ambulatory surgery settings. Patients with private insurance and those at for-profit, nonteaching hospitals are most likely to undergo robotic-assisted procedures. This study provides baseline data on the extent to which ambulatory procedures involve robotic assistance. HCUP (10/20/2021) 1 Robotic-Assisted Ambulatory Surgery INTRODUCTION Robotic-assisted surgery is the use of small surgical tools manipulated by a robotic arm, which a surgeon controls with a computer.1 Since 1985 when robotic-assisted surgery first was used in neurosurgical biopsy, robotic techniques have become increasingly common.2,3 In 2017, more than 600,000 robotic-assisted operations occurred in the United States, making the nation the largest market for robotic surgery.4 Robotic techniques are particularly useful in certain subspecialties, including gynecology, urology, and general surgery, that often involve procedures in the deep pelvis where robotic technology can increase dexterity (e.g., through 360-degree motion) and visualization (e.g., through three-dimensional images) within confined spaces.5 In recent decades, the volume of and revenue associated with outpatient operations have steadily increased.6-10 This growth is driven in part by improved technology in ambulatory surgical settings. An increase in the use of robotic technology in outpatient settings has been documented.11-15 However, most studies of the safety and efficacy of robotic surgery have been conducted in inpatient settings and have yielded mixed results. The limited research in outpatient settings has focused on specific robotic procedures, such as hysterectomy or cholecystectomy, or has been conducted in a select number of surgical centers.11,12,16,17 Benefits of robotic surgery are reported to include faster recovery; less postoperative pain and analgesic use; decreased risk of blood loss, infection, and other complications; and enhanced cosmetic results.18,19 However, other research has suggested that the benefits for patients are minimal and may not warrant the costly initial capital investment for equipment; ongoing costs of maintenance, training, and staffing; and longer operating times.20-22 Furthermore, compared with other surgical approaches, robotic-assisted hysterectomy may be associated with shorter survival times among patients with cervical cancer, as well as higher postoperative revisit rates among women with nonmalignant conditions.23-26 There is a dearth of information not only on the efficacy of robotic surgery in outpatient settings but also on how often various outpatient procedures are performed robotically, types of facilities that use this technology, characteristics of patients who undergo these procedures, and variation in spending by surgical approach. In this study, we describe the degree to which robotic technology is used throughout ambulatory surgery settings across hospitals in the United States and assess how the proportion of procedures performed robotically differs across procedure and facility types, and across patient populations. In a secondary analysis, we explore differences in spending between robotic-assisted and nonrobotic laparoscopic procedures. METHODS Data Source For our primary analysis, we used the 2016 Healthcare Cost and Utilization Project (HCUP) State Ambulatory Surgery and Services Databases (SASD)27 for 26 states (see Acknowledgements for a list of states). We included hospital-owned outpatient facilities (as opposed to free-standing facilities, for which data are not contributed by every state) that could be linked to the American Hospital Association Annual Survey, the source of data for facility characteristics. To calculate annual volume, we selected facilities that contributed data in all 4 quarters of 2016 and did not have irregularities in quarterly volume. Level II Healthcare Common Procedure Coding System (HCPCS) codes are used to identify robotic surgery, but not all facilities consistently report Level II HCPCS codes. Therefore, we included only facilities HCUP (10/20/2021) 2 Robotic-Assisted Ambulatory Surgery at which at least 90% of outpatient discharges had a Level II HCPCS code documented in any procedure listed on the record. Charges are documented in the SASD, but those charges generally are higher relative to the actual cost of care and the amount that hospitals charge for similar services varies. Currently, unlike for inpatient data, there are no generally accepted cost estimation methods for ambulatory surgery data.28 Therefore, we supplemented our analysis of charges in the SASD with payments using data from the IBM® MarketScan® Commercial Database for patients with employer-sponsored health insurance in the same 26 states. For consistency with the MarketScan commercial data, we compared these results with a similar analysis of charges in the SASD, which was restricted to patients with private insurance. To better interpret the charge and payment results across these two different data sources, we verified the regional distribution of ambulatory surgery visits included in this study from the SASD and the MarketScan Commercial Database (see Appendix Table A.1). The distributions generally were similar across the two data sources. Definition of Robotic-Assisted Procedures We identified robotic-assisted procedures as those with a Level II HCPCS code of S2900, G0339, or G0340 (see Appendix Table A.2). We focused on procedures for which 1% or more were performed robotically. Those procedures included cervical excision and trachelectomy; cholecystectomy; colpopexy and other procedures to treat pelvic organ prolapse; excision of lesions of the ovary, pelvic viscera, or peritoneal surface; hysterectomy; incisional and other ventral hernia repair; inguinal and femoral hernia repair; myomectomy; oophorectomy; paraesophageal hernia repair and esophagogastric fundoplasty; prostatectomy; and pyeloplasty. More than 1% of outpatient knee arthroplasty procedures were performed robotically, but we excluded this procedure because it involves different equipment and functions than the robotic techniques applied to the intra-abdominal/pelvic procedures listed above. For each procedure, we categorized the approach as robotic, nonrobotic laparoscopic, or nonrobotic nonlaparoscopic (i.e., all other approaches, which generally include open approaches, either through an incision or via a natural opening, such as the vagina). See Appendix Table A.3 for procedure codes and definitions. Patient and Hospital Characteristics We examined the proportion of procedures performed robotically by patient characteristics (firstlisted expected payer, urban/rural location of patient residence, and quartiles of median household income in the patient’s ZIP Code of residence) and by hospital characteristics (region, ownership, and teaching status), based on definitions found in HCUP documentation.29 Spending Using data from the SASD, we examined billed charges per procedure, which generally include facility charges but not professional fees and noncovered charges.29 For consistency with the data from the MarketScan Commercial Database, we limited our analysis of charges in the SASD to patients with an expected payer of private insurance. For consistency with the types of charges reported in the SASD, we limited our analysis of payments (allowed charges) among patients with private, employer-sponsored insurance coverage in the MarketScan Commercial Database to facility payments. Payments include those made by the insurer and out-of-pocket costs to the patient. HCUP (10/20/2021) 3 Robotic-Assisted Ambulatory Surgery Analysis We examined differences in the proportion of procedures performed robotically across patient and hospital characteristics. We also used Poisson regression models to examine the difference in charges and payments associated with robotic-assisted surgery versus the nonrobotic laparoscopic approach. To isolate spending associated with robotic technology, above what would be observed for a traditional laparoscopic approach, we focused on these two approaches and not on open approaches. We present results from unadjusted models, as well as models that included age as a covariate and fixed effects for the hospital identifier in the SASD. The latter control for hospital-level differences in charges; thus, the charge difference estimated by the adjusted models reflects within-hospital comparisons across surgical approaches. Similarly, the MarketScan Commercial Database models included a fixed effect for the employer health insurance plan, which controls for differences in payments that may result from variation in negotiations between insurers and hospitals. We included age and not a broader set of patient clinical characteristics (e.g., uterine size) because we did not want to overcontrol for conditions (e.g., cancer) that might indicate need for a particular surgical approach but also complicate procedures, leading to higher charges. RESULTS Ambulatory Procedures Performed Robotically We identified 1.8 million ambulatory procedures of interest and 65,000 robotic-assisted operations across the 12 procedure categories (Figure 1). The proportion of ambulatory procedures performed robotically was greatest for pyeloplasty, myomectomy, and hysterectomy—constituting 15.1% of 1,903, 14.7% of 14,069, and 10.1% of 301,251 procedures, respectively. For these three procedures, 60-74% involved nonrobotic laparoscopic techniques. For cervical excision/trachelectomy and prostatectomy, nearly 8% of procedures were robotic assisted. Less than 5% of the remaining procedures were performed robotically. The highest volume procedures were hernia repair and cholecystectomy. However, the proportion of roboticassisted procedures was lowest for cholecystectomy (1.4%) and was 1.8% for hernia repair overall (1.6% for incisional/other ventral hernia repair; 1.9% for inguinal/femoral hernia repair; 2.1% for paraesophageal hernia repair and esophagogastric fundoplasty). Together hernia repair (N=12,811 robotic procedures) and cholecystectomy (N=6,778 robotic procedures) constituted nearly 20,000 ambulatory robotic procedures. HCUP (10/20/2021) 4 Robotic-Assisted Ambulatory Surgery Figure 1. Surgical Approach for 12 Select Procedures Performed in Hospital-Owned Ambulatory Surgery Centers in 26 States, 2016 Excision of lesions indicates Excision of lesions of ovary, pelvic viscera, or peritoneal surface; Colpopexy, Colpopexy and other procedures to treat pelvic organ prolapse; Paraesophageal hernia repair, Paraesophageal hernia repair and esophagogastric fundoplasty. HCUP (10/20/2021) 5 Robotic-Assisted Ambulatory Surgery Robotic Surgery by Patient Characteristics For the 12 ambulatory procedures combined, the proportion with robotic assistance was lower among Medicare (1.9%) and Medicaid (2.5%) patients and among patients with an expected payer of self-pay/no charge (1.9%), compared with patients with private insurance (4.1%) (P><.001) (Table 1). For the 12 procedures combined, the proportion with robotic assistance was lower among patients living in micropolitan (1.8%) and rural areas (1.8%), compared with those living in metropolitan areas (3.7%) (P><.001), and also lower among patients from the lowest income communities (income quartile 1; 2.6%), compared with those from the highest income communities (quartile 4; 4.1%; p><0.001). Generally, similar findings were observed for each of the 12 procedures. Table 1. Robotic-Assisted Surgery for Select Procedures Performed in Hospital-Owned Ambulatory Surgery Centers in 26 States by Patient Characteristic, 2016 Procedure Percentage of Procedures With Robotic Assistance Primary Expected Payer Location Community Income Medicare Medicaid Private Self-Pay/No Charge Metropolitan Micropolitan Rural Quartile 1 (Lowest) Quartiles 2-3 Quartile 4 (Highest) Total 12 procedures 1.9§ 2.5§ 4.1 1.9§ 3.7 1.8§ 1.8§ 2.6§ 3.3§ 4.1 Pyeloplasty 11.9§ 11.3§ 17.7 —| 16.1 11.8 9.9§ 12.9§ 13.4§ 20.8 Procedures of female organs, total 4.4§ 4.7§ 7.8 5.2§ 7.5 3.7§ 4.0§ 5.4§ 6.6§ 8.6 Myomectomy 13.5 10.2§ 15.8 7.4§ 15.3 5.5§ 5.1§ 12.0§ 14.4§ 17.3 Hysterectomy 7.1§ 8.2§ 11.1 8.4§ 11.1 5.8§ 6.2§ 8.3§ 9.7§ 12.9 Cervical excision/ trachelectomy —| 8.6 8.6 —| 8.6 —| —v 3.9§ 9.2 8.5 Colpopexy* 2.3§ 4.0§ 5.6 3.0§ 4.8 2.2§ 2.4§ 3.2§ 4.1§ 5.7 Oophorectomy 2.8 1.1§ 3.0 1.2§ 2.8 1.0§ 1.0§ 1.7§ 2.5§ 3.3 Excision of lesions† 6.9§ 2.3§ 5.3 2.9§ 5.2 2.1§ 1.9§ 3.4§ 4.4§ 6.4 Prostatectomy 2.9§ —| 10.9 —| 8.0 7.3 4.6§ 6.4 8.3 7.8 Hernia repair, total 1.3§ 1.3§ 2.1 1.1§ 1.9 1.0§ 0.9§ 1.5§ 1.8 1.8 Paraesophageal‡ 1.8 3.6§ 2.1 —| 2.3 1.5§ 1.8 1.7§ 2.2 2.4 Inguinal/femoral 1.4§ 1.2§ 2.4 1.3§ 2.1 0.9§ 1.0§ 1.7§ 2.0 1.9 Incisional/other ventral 1.3§ 1.3§ 1.9 0.9§ 1.8 1.1§ 0.8§ 1.4§ 1.7 1.7 Cholecystectomy 0.9§ 1.5 1.6 0.6§ 1.6 0.9§ 0.9§ 1.1§ 1.5 1.5 * Colpopexy and other procedures to treat pelvic organ prolapse. † Excision of lesions of ovary, pelvic viscera, or peritoneal surface. ‡ Paraesophageal hernia repair and esophagogastric fundoplasty. § Chi-square test for difference in the percentage of robotic procedures = P><.05 (reference groups were patients with private insurance, from metropolitan areas, and with community income in quartile 4). | Not shown; number of events ≤10. HCUP (10/20/2021) 6 Robotic-Assisted Ambulatory Surgery Robotic Surgery by Hospital Characteristics For the 12 ambulatory procedures combined, the proportion with robotic assistance was higher among hospitals in the Northeast (4.3%) than among hospitals in the South (3.4%), West (2.6%), and Midwest (2.5%) (P><.001); higher for private for-profit hospitals (6.2%) than for private nonprofit (3.0%) and public hospitals (1.1%) (P><.001); and higher for nonteaching (4.3%) than for teaching hospitals (1.7%) (P><.001) (Table 2). These findings were observed for most of the 12 procedures, including hysterectomy for which the proportion performed robotically reached 15.4% in the Northeast, 15.7% in private for-profit hospitals, and 12.5% in teaching hospitals. However, for several other procedures, robotic assistance was slightly more common in the West than in the Northeast, including total hernia repair (2.4% West, 2.2% Northeast; P=.01) and cholecystectomy (2.5% West, 1.9% Northeast; P><.001). Table 2. Robotic-Assisted Surgery for Select Procedures Performed in Hospital-Owned Ambulatory Surgery Centers in 26 States by Hospital Characteristic, 2016 Procedure Percentage of Procedures With Robotic Assistance Census Region Ownership Teaching Northeast Midwest South West Private, for Profit Private, Nonprofit Public Teaching Nonteaching Total 12 procedures 4.3 2.5§ 3.4§ 2.6§ 6.2 3.0§ 1.1§ 1.7 4.3§ Pyeloplasty 19.5 10.6§ 17.2 —| 15.7 16.1 7.6§ 16.0 15.0 Procedures of female organs, total 9.5 5.3§ 6.9§ 3.0§ 11.1 6.5§ 1.6§ 3.3 8.4§ Myomectomy 24.5 6.1§ 12.1§ 4.1§ 15.6 15.5 2.5§ 4.4 17.2§ Hysterectomy 15.4 8.4§ 9.8§ 4.2§ 15.7 9.8§ 2.7§ 5.2 12.5§ Cervical excision/ trachelectomy 12.1 3.6§ 9.0 —| 18.3 7.7§ —| 5.9 8.8 Colpopexy* 6.4 2.6§ 4.6§ 3.3§ 8.6 3.9§ 0.8§ 2.3 5.1§ Oophorectomy 3.3 1.1§ 3.3 1.1§ 5.2 2.4§ 0.3§ 1.2 3.2§ Excision of lesions† 6.4 2.5§ 5.6§ 2.1§ 8.8 4.4§ 0.7§ 2.5 5.8§ Prostatectomy 5.1 3.1§ 12.2§ —| 4.5 8.9§ 2.6 4.8 8.9§ Hernia repair, total 2.2 1.3§ 1.7§ 2.4§ 3.9 1.5§ 0.9§ 1.2 2.0§ Paraesophageal‡ 3.4 1.6§ 1.5§ 9.5§ 4.6 1.6§ 1.4§ 1.0 3.0§ Inguinal/femoral 2.3 1.4§ 1.9§ 2.6§ 4.5 1.6§ 1.0§ 1.4 2.2§ Incisional/other ventral 2.1 1.1§ 1.7§ 1.9 3.5 1.4§ 0.9§ 1.2 1.9§ Cholecystectomy 1.9 1.0§ 1.3§ 2.5§ 3.4 1.1§ 0.9§ 0.8 1.9§ * Colpopexy and other procedures to treat pelvic organ prolapse. † Excision of lesions of ovary, pelvic viscera, or peritoneal surface. ‡ Paraesophageal hernia repair and esophagogastric fundoplasty. § Chi-square test for difference in the percentage of robotic procedures = P><.05 (reference groups were patients with private insurance, from metropolitan areas, and with community income in quartile 4). | Not shown; number of events ≤10. HCUP (10/20/2021) 7 Robotic-Assisted Ambulatory Surgery Charges and Payments for Robotic Surgery for Patients With Private Insurance In unadjusted models for the 12 ambulatory procedures combined, among patients with an expected payer of private insurance, charges for procedures involving robotic surgery were 61.8% (95% confidence interval [CI]: 60.7%, 62.9%) higher than those for nonrobotic laparoscopic procedures (Table 3). Adjusting for age and hospital fixed effects attenuated the association between robotic versus nonrobotic laparoscopic surgery and charges to 17.9% (95% CI: 12.1%, 24.0%). In the models adjusted for age and hospital fixed effects, charges generally were higher for robotic than for nonrobotic laparoscopic procedures, ranging from 10.1% (95% CI: 6.2%, 14.2%) higher for hysterectomy to 45.9% (95% CI: 34.0%, 58.8%) higher for excision of lesions of the ovary, pelvic viscera, or peritoneal surface. We did not find that robotic surgery was associated with higher charges for pyeloplasty, colpopexy, prostatectomy, and paraesophageal hernia repair (P>.05). Payments, as measured in the MarketScan Commercial Database for individuals with private employer-sponsored health coverage, were 29% lower than charges as measured in the SASD. For the 12 procedures combined, the average payment for robotic surgery was $11,500, whereas the average charge was $40,000. In the adjusted models of payments in the MarketScan Commercial Database, we found no association between robotic versus nonrobotic laparoscopic surgery and payments for the 12 procedures combined (1.033; 95% CI: 0.992, 1.075). For some procedures, payments were higher for robotic-assisted procedures than for nonrobotic laparoscopic procedures, ranging from 14.3% (95% CI: 5.8%, 24.2%) higher for robotic inguinal/femoral hernia repair to 65.6% (95% CI: 18.2%, 132.2%) higher for robotic paraesophageal hernia repair. We did not find an association between robotic-assisted surgery and payments for colpopexy, prostatectomy, or incisional/other ventral hernia repair. Robotic versus nonrobotic laparoscopic surgery was associated with lower payments for pyeloplasty and hysterectomy.. Association of Robotic-Assisted Surgery With Charges and Payments Among Patients With Private Insurance* Procedure Charges or Payments, $ (Mean) Robotic T-test for difference in charges or payments between robotic and nonrobotic procedures = P<0.05. ¶ Not shown; number of events ≤10. ** By definition, cervical excision/trachelectomy is not performed using a nonrobotic laparoscopic approach and therefore was not included in the regression models. HCUP (10/20/2021) 9 Robotic-Assisted Ambulatory Surgery DISCUSSION In this study of hospital-owned outpatient facilities in 26 states, we captured 65,000 robotic ambulatory surgery visits for 12 procedures in which robotic techniques are commonly used. Our findings suggest that robotic-assisted surgery still accounts for a relatively small share of total ambulatory procedures. Among the procedures examined, the proportion of roboticassisted surgery ranged from 1.4% for cholecystectomy (a very common ambulatory procedure) to 15.1% for pyeloplasty (a relatively uncommon ambulatory procedure). Thus, despite reports that robotic technology is becoming more common at outpatient facilities, for most ambulatory procedures, robotic technology rarely is used. However, robotic techniques may be concentrated at relatively few hospitals that have invested in technology and surgical training and that take referrals for cases indicating a robotic approach.5 Our results suggest that hospitals with a higher proportion of ambulatory robotic procedures are likely to be nonteaching and for-profit hospitals in the Northeast. Studies have documented disparities in access to robotic surgery.11,30,31 After controlling for demographic and clinical factors, Price et al. (2017) found that race/ethnicity, Medicaid enrollment, and income were associated with lower odds of robotic hysterectomy.30 We found that robotic hysterectomy and most of the other ambulatory robotic procedures were less likely to be performed among patients without private insurance, from nonmetropolitan areas, and with lower community-level incomes than among patients with private insurance, from metropolitan areas, and with higher community-level incomes. Some studies have noted that the minimal benefits of robotic surgery for patients may not justify the expense.18-20 Our analysis of hospital charges in the SASD aligned with payments from the MarketScan Commercial Database for privately insured patients can shed light on issues related to the financing of these kinds of procedures. There are two related points worth mentioning. First, for these 12 ambulatory procedures overall, payments for robotic-assisted procedures constituted 29% of charges for patients with private insurance. Thus, although hospitals may bill more for robotic surgery, negotiated payments between hospitals and private insurance plans are much lower, as are prices and reimbursement rates in general when compared with charges.32 We supplemented our analysis of charges with payments because currently there is no accepted cost estimation methodology for ambulatory surgery data. However, the difference between payments and charges in our study is consistent with the ratio of costs to charges for total inpatient stays in the United States in 2016, which was 25%, down from 44% in 2000.33 Second, numerous studies have documented higher spending associated with robotic versus nonrobotic surgery.34-41 In adjusted models, we found that charges were 18% higher for robotic than for nonrobotic laparoscopic procedures for the 12 procedures overall. However, payments were not higher after adjusting for differences across plan reimbursement structures. Thus, within plans, payments for robotic procedures were not statistically different from those for nonrobotic laparoscopic procedures. These findings warrant more research to understand how costs associated with robotic surgery are distributed across patients, payers, and hospitals. Salient issues include whether there may be long-term effects of robotic surgery on health insurance premiums and out-of-pocket costs. A recent study found robotic surgery was associated with lower out-of-pocket costs for oncologic procedures relative to open surgery but did not examine nonrobotic laparoscopic approaches.42 Additionally, future studies may explore reimbursement for robotic surgery, particularly for patients with Medicare, which does not reimburse claims based on the Level II HCPCS code S2900 for robotic surgery (the most common code for robotic surgery used in our data), but only HCUP (10/20/2021) 10 Robotic-Assisted Ambulatory Surgery based on Current Procedural Terminology codes that differentiate laparoscopic from nonlaparoscopic procedures.43 Future research also may focus on the extent to which reimbursement by private or public payers covers the cost of robotic-assisted surgery for hospitals and hospital responses to recoup costs. For instance, hospitals may shift costs across robotic and nonrobotic surgical visits.39 Outpatient robotic surgery also may help offset the investment made for inpatient procedures. Finally, robotic approaches may be favored for procedures involving the deep pelvis where improved visualization and the greater degrees of freedom of robotic instruments substantially facilitate the procedure. For other procedures, including cholecystectomy, inguinal hernia repair, and appendectomy, robotic visualization and instrumentation may be no more advantageous than that with standard laparoscopic techniques21; thus, benefits of a robotic approach may not outweigh additional costs. Although the proportion of robotic cholecystectomies and inguinal/femoral hernia repairs was relatively low (below 2%), second to hysterectomy, these two procedures constituted the second largest number of ambulatory robotic procedures and therefore should be monitored by researchers assessing the safety and efficacy of robotic surgery in ambulatory settings. Our study has several limitations. Although we excluded hospitals with fewer than 90% of ambulatory surgery visits with a Level II HCPCS code, the HCPCS code for robotic surgery still may be underreported if it is not commonly used for billing.43 To our knowledge, this study provides the most comprehensive summary of use of robotic technology for hospital-based ambulatory procedures in the United States. Although we included data from only 26 states, these states constituted 58% of the U.S. population in 2016.44 However, the proportion of procedures performed robotically in these states may not be generalizable to other states. Finally, we did not examine clinical outcomes of ambulatory robotic-assisted surgery, and without validated estimation methods, we cannot comment on outpatient costs, nor was this the goal of the current study. We suspect that the spending differentials we report between robotic surgery and the nonrobotic laparoscopic approach could be biased downward because roboticrelated Level II HCPCS codes may be underreported and because hospitals can shift costs from robotic to nonrobotic surgical visits. Because we did not include inpatient data, we were unable to monitor how often complications of ambulatory robotic surgery resulted in an inpatient stay or further surgical intervention in the inpatient setting. CONCLUSION Although the proportion of ambulatory robotic procedures was generally low, 1 in 10 outpatient hysterectomies were performed robotically. Hysterectomy is a common ambulatory procedure, and more than 30,000 outpatient robotic hysterectomies in 26 states were included in this study. Only 1.4% of cholecystectomies and 1.9% of inguinal/femoral hernia repairs were robotic assisted, yet, next to hysterectomy, these two procedures constituted the second highest number of ambulatory robotic operations (nearly 20,000). Given questions about the benefits of robotic-assisted surgery for certain procedures (e.g., cholecystectomy and inguinal hernia repair)20 and emerging evidence documenting poorer outcomes for patients undergoing roboticassisted hysterectomy for cervical cancer,22-25 our study is an important step in describing some basic characteristics of outpatient robotic surgery and advancing research on this topic. Additional studies using longitudinal data may reveal whether the findings we observed are static or dynamic, and those comparing data from inpatient and outpatient settings may more fully describe the use of robotic technology. > Robotic Surgery Phong Thanh Nguyen, M. Lorate Shiny, K. Shankar, Wahidah Hashim, Andino Maseleno Robotic Surgery 996 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: F13030886S219/2019©BEIESP DOI:10.35940/ijeat.F1303.0886S219 Table 2: Limitations of humans and robots II. HISTORY At National Aeronautics and Space Centre (NASA) in early 1980’s the concept of robotic surgery was first introduced. The surgical and virtual reality robots were developed with Stanford Research Institute. The concept of telepresence surgery was proposed. In 1990’s robotic surgery was commercialized. Complete development of robotic surgery was the next step. In late 1990’s the da Vinci robotic system and Zeus robotic system were presented. In both robotic systems the surgical workstation controlled from remote manipulators. There has been a wide development in less than 20 years time. The Computer