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Cost-Minimization Analysis of Robotic-Assisted, Laparoscopic, and Abdominal Sacrocolpopexy
Original Article
Cost-Minimization Analysis of Robotic-Assisted, Laparoscopic, and Abdominal Sacrocolpopexy John P. Judd, MD*, Nazema Y. Siddiqui, MD, Jason C. Barnett, MD, Anthony G. Visco, MD, Laura J. Havrilesky, MD, and Jennifer M. Wu, MD, MPH From the Divisions of Urogynecology and Pelvic Reconstructive Surgery (Drs. Judd, Siddiqui, Visco, and Wu) and Gynecologic Oncology (Drs. Barnett and Havrilesky), Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina.
ABSTRACT Study Objective: To perform a cost-minimization analysis comparing robotic-assisted, laparoscopic, and abdominal sacrocolpopexy. Design: Cost-minimization analysis using a micro-costing approach (Canadian Task Force classification III). Measurements and Main Results: A decision model was developed to compare the costs (2008 US dollars) of robotic, laparoscopic, and abdominal sacrocolpopexy. Our model included operative time, risk of conversion, risk of transfusion, and length of stay (LOS) for each method. Respective baseline estimates for robotic, laparoscopic, and abdominal sacrocolpopexy procedures included operative time (328, 269, and 170 minutes), conversion (1.4%, 1.8%, and 0%), transfusion (1.4%, 1.8%, 3.8%), and LOS (1.0, 1.8, and 2.7 days). Two models were used, the Robot Existing model, that is, current hospital ownership of a robotic system, and the Robot Purchase model, that is, initial hospital purchase of a robotic system, with purchase and maintenance costs amortized and distributed across robotic procedures. Sensitivity analyses were performed to assess the effect of varying each parameter through its range. For the Robot Existing robot model, robotic sacrocolpopexy was the most expensive, $8508 per procedure compared with laparoscopic sacrocolpopexy at $7353 and abdominal sacrocolpopexy at $5792. Robotic and laparoscopic sacrocolpopexy became cost-equivalent only when robotic operative time was reduced to 149 minutes, robotic disposables costs were reduced to $2132, or laparoscopic disposable costs were increased to $3413. Laparoscopic and abdominal sacrocolpopexy became cost-equivalent only when laparoscopic disposable costs were reduced to $668, mean LOS for abdominal sacrocolpopexy was increased to 5.6 days, or surgeon reimbursement for abdominal sacrocolpopexy exceeded $2213. The addition of robotic purchase and maintenance costs resulted in an incremental increase of $581, $865, and $1724 per procedure when these costs were distributed over 60, 40, and 20 procedures per month, respectively. Conclusion: Robotic sacrocolpopexy was more expensive compared with the laparoscopic or abdominal routes under the baseline assumptions. Journal of Minimally Invasive Gynecology (2010) 17, 493–499 Ó 2010 AAGL. All rights reserved. Keywords:
Cost; Cost analysis; Cost-minimization analysis; Laparoscopic; Robotic; Robotic-assisted; Sacral colpopexy; Sacrocolpopexy
Pelvic organ prolapse is a common condition, resulting in more than 200 000 surgical procedures each year in the United States [1]. It is estimated that 1 in 9 women who live to age 80 The authors have no commercial, proprietary, or financial interest in the products or companies described in this article. Dr. Visco is a proctor and assists with procedure development for Intuitive Surgical, Inc. Presented at the 30th Annual Scientific Meeting of the American Urogynecologic Society, Hollywood, Florida, September 24–26, 2009. Corresponding author: John P. Judd, MD, Division of Urogynecology and Pelvic Reconstructive Surgery, Duke University Medical Center, DUMC 3192, Durham, NC 27710. E-mail: [email protected] Submitted January 3, 2010. Accepted for publication March 6, 2010. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2010 AAGL. All rights reserved. doi:10.1016/j.jmig.2010.03.011
years will undergo surgical treatment of prolapse or urinary incontinence [2]. Abdominal sacrocolpopexy is recognized as a well-accepted and durable repair for advanced apical prolapse, with demonstrated long-term success [3,4]. Until recently, sacrocolpopexy required the associated morbidity of an abdominal incision. However, with development of the laparoscopic approach to treatment of sacrocolpopexy, patients experience the benefits of a minimally invasive alternative to laparotomy, including decreased blood loss and shorter hospital stay, with comparable operative time and clinical outcome [5,6]. The advanced laparoscopic surgical skills required for laparoscopic sacrocolpopexy are challenging and may limit use of this procedure. With the implementation of robotic-assisted laparoscopy using the da Vinci Surgical System (Intuitive Surgical, Inc.,
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Fig. 1. Decision model comparing robotic-assisted, laparoscopic, and abdominal sacrocolpopexy, beginning with diagnosis of advanced prolapse.
Sunnyvale, CA), proponents contend that complex laparoscopic maneuvers can be accomplished with less difficulty, simplifying the procedure and shortening operative time [7]. In a recent retrospective study, patients who underwent robotic-assisted sacrocolpopexy experienced similar vaginal vault support results at 6 weeks when compared with patients who underwent abdominal sacrocolpopexy [8]. Furthermore, compared with the abdominal approach, robotic-assisted sacrocolpopexy was associated with less blood loss, similar rates of perioperative complications, and shorter length of hospital stay (LOS), but at the expense of longer operative time. When considering adoption of a new and rapidly evolving technology, an important factor to consider is cost. Recent data have shown that robotic-assisted sacrocolpopexy produces the highest hospital charges when compared with laparoscopic or abdominal sacrocolpopexy, with no significant difference in Medicare reimbursement between the 3 approaches [9]. It is important for any hospital or practice to have a clear understanding of the costs associated with adoption and implementation of a urogynecologic robotic program or expansion of an existing robotic program to include robotic-assisted sacrocolpopexy. Data to minimize healthcare costs while conveying the most benefit to patients are currently lacking. Thus, we performed a costminimization analysis to compare robotic-assisted with laparoscopic and abdominal sacrocolpopexy.
Material and Methods Decision Model To compare the costs of sacrocolpopexy performed using robotic-assisted, laparoscopic, and abdominal techniques, we developed a decision model [10,11]. A decision model is
ideal for a cost analysis because it incorporates both outcomes and costs and enables sensitivity analyses. Our method is based on the guidelines of the Panel on CostEffectiveness in Health and Medicine [12]. This analysis was conducted from a healthcare system perspective and costs were 2008 US dollars. Inasmuch as sacrocolpopexy is performed in a similar fashion regardless of the route of surgery and because the short-term outcomes of roboticassisted, laparoscopic, and abdominal sacrocolpopexy are comparable [5,8,13], we assumed that they were equally effective in the treatment of advanced prolapse. Given this assumption of equivalent outcomes, we focused only on costs and, therefore, conducted a cost-minimization analysis and not a cost-effectiveness analysis. The model was based on a hypothetical cohort of women with advanced pelvic organ prolapse who have elected to undergo surgical correction via sacrocolpopexy with synthetic polypropylene mesh (Fig. 1). Women can opt for a sacrocolpopexy via 1 of 3 routes of surgery: robotic-assisted, laparoscopic, or abdominal. For the robotic-assisted and laparoscopic cohorts, the model included the possibility of conversion to an abdominal procedure. Conversions were defined as ‘‘early,’’ that is, those occurring before robot docking in the roboticassisted group or during the diagnostic portion of the case in the laparoscopic group, or ‘‘late,’’ that is, once hysterectomy or sacrocolpopexy was under way. The risk of blood transfusion was incorporated into all cohorts, with maximum transfusion volume assumed to be 2 units of packed red blood cells. We considered only short-term events that were likely to occur during the initial admission. Because of the rarity of enterotomy or ureteral injury, we chose blood transfusion as the only secondary event for which we calculated cost during the initial hospitalization [3].
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Table 1
Robotic-assisted, laparoscopic, and abdominal sacrocolpopexy parameter estimatesa Robotic-assisted sacrocolpopexy
Laparoscopic sacrocolpopexy
Abdominal sacrocolpopexy
Parameter
Baseline
Range
Baseline
Range
Baseline
Range
Operative time, min Conversion risk, % Transfusion risk, % Length of stay, days
328 [8] 1.4 [8] 1.4 [8] 1 [8]
130 [7]–383 [8] 0–12 [16] 0–5 [3] 0.5–3 [7]
269 [13] 1.8 [13] 1.8 [13] 1.8 [13]
97 [14]–334 [13] 0–12 [16] 0–5 [3] 0.5–3.0 [13]
170 [15] NA 3.8 [8] 2.7 [8]
110 [15]–286 [8] NA 0 [16]–17 [3] 2 [16]–6 [13]
NA 5 data not available. a References given in brackets.
Parameter Estimates
Costs
Parameter estimates were derived from a systematic review of the medical literature. In decision analysis, data for the parameters in the model are often abstracted from a systematic literature search [12]. Estimates from the highest quality studies are then used as the baseline, or base-case, estimates, and the lowest and highest reported values are used for the sensitivity analyses. A PubMed search was performed in February 2009 using the keywords ‘‘Colpopexy,’’ ‘‘Sacral colpopexy,’’ and ‘‘Sacrocolpopexy’’ combined with ‘‘Abdominal,’’ ‘‘Laparoscopic,’’ ‘‘Robotic,’’ or ‘‘Robotic-assisted.’’ This search was limited to human subjects and English, with exclusion of editorials, letters, or comments. Studies with fewer than 20 subjects were excluded, whereas studies in which concomitant procedures including hysterectomy and colporrhaphy were performed were included because they are representative of situations commonly encountered in clinical practice. On the basis of the recommendations of the US Preventive Services Task Force, each identified article was given a hierarchical rank based on study design, with data from higher quality studies such as randomized controlled trials and comparative studies given greater weight than data derived from case series [12]. Because no studies comparing all modes of sacrocolpopexy were identified, data were obtained from 7 observational studies. Two comparative studies, Geller et al [8], representing the largest comparative study of robotic-assisted and abdominal sacrocolpopexy, and Paraiso et al [13], representing the largest comparative study of laparoscopic vs abdominal sacrocolpopexy, reported the highest quality data and, therefore, were the source for many of the parameter estimates in the base-case analysis. Parameter estimates were obtained for operative time, risk of conversion (for laparoscopic and robotic procedures), risk of transfusion, and LOS (Table 1). In determining the ranges of each parameter estimate, the extracted data from the previously identified 7 studies were reviewed, and the highest and lowest estimates determined in such a way as to provide the widest range of potential values (Table 1). Estimates listed without reference were assumptions based on expert opinion; thus, we varied these parameters widely in the sensitivity analyses to ensure model robustness.
Costs in 2008 US dollars were derived using a microcosting approach based on our own institutional data (Table 2). For each procedure, physician reimbursement was derived from current Medicare reimbursement rates for anesthesia CPT code 00840 and surgeon CPT codes 57425 (robotic-assisted and laparoscopic) and 57283 (abdominal) [18]. Procedure costs were derived by examining the perioperative, intraoperative, and postoperative costs incurred at Duke medical center. For all approaches, perioperative and postoperative costs accounted for the cost of time in preoperative holding and the postanesthesia care unit, as well as room and board for the duration of hospital stay. Anesthesiology costs consisted of a base fee of $1413 per procedure that included initial setup and professional fees. Additional costs were then applied based on the operative time required for each approach (Table 2). For intraoperative costs, we accounted for standardized operating room costs including cost per minute of operative time, anesthesia fees per minute, and surgical and anesthesia physician reimbursement (Table 2). In addition, we included disposable costs related to each procedure such as drapes, gowns, and gloves; single-use instruments; sutures; Foley catheter; and miscellaneous items such as the electrosurgical generator, scalpel blades, uterine manipulators, and laparoscopic trocars as indicated. For both robotic-assisted and laparoscopic sacrocolpopexy, we sought to minimize the cost per procedure of disposable instruments. For the robotic-assisted approach, the cost of each reusable robotic instrument was evenly distributed across 10 robotic procedures based on the 10 lives available for each robotic instrument before they must be replaced. Because procedures using laparoscopic and abdominal surgical equipment are now commonplace, we assumed that all hospital systems already own the required surgical equipment for these procedures and, thus, no additional investment was needed for this equipment. Reusable instrumentation for both laparoscopic and abdominal surgery was also assumed to have no cost because of the substantial lifetime of the instrumentation. To estimate the cost of conversion, we assumed that a late conversion from robotic-assisted or laparoscopic sacrocolpopexy to laparotomy would incur the full cost of the current
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Cost estimates for robotic-assisted, Laparoscopic, and abdominal sacrocolpopexy Robotic-assisted sacrocolpopexy
Laparoscopic sacrocolpopexy
Abdominal sacrocolpopexy
Cost, 2008 US dollars
Baseline
Range
Baseline
Range
Baseline
Anesthesia Professional fee, surgeon Operating room Disposable equipment, early conversion Disposable equipment, late or no conversion Postanesthesia care Room and board, pharmacy [17], laboratory
842 893 2728 1924
334–983 893–4156 1081–3185 NA
690 893 2237 1677
249–857 893–4156 807–2778 NA
436 638 1414 NA
282–734 638–3276 915–2379 NA
3293
1500–4500
2244
500–3500
966
0–2000
216 1198
77–378 468–2748
216 1654
77–378 468–2748
404 2489
102–816 1851–5499
Range
NA 5 not applicable.
surgical approach, along with the cost of the additional operative time required for the conversion. This additional operative time was assumed to be 30 minutes at baseline, with a range of 0 to 60 minutes. Early conversion for robotic-assisted or laparoscopic sacrocolpopexy, however, reverted to the baseline surgical time of abdominal sacrocolpopexy, with an additional amount of operative time required for the initial laparoscopic portion of the procedure and time to convert, again assumed to be 30 minutes. We recognized that fewer laparoscopic instruments would have been used during an early conversion from a robotic-assisted or laparoscopic approach, and disposable costs were calculated appropriately. For early conversion of robotic-assisted sacrocolpopexy, only initial laparoscopic instruments such as graspers and monopolar endoshears were included as disposable equipment. Because the robotic system had not yet been docked, no lives were deducted from the robotic instruments, and, thus, no cost was accrued for the robotic instrumentation. For laparoscopic sacrocolpopexy, there was no difference in disposable equipment use between our early or late conversion arms because all instruments were assumed opened at the beginning of the procedure. To account for postoperative care, laboratory tests including a complete blood cell count and basic metabolic panel were used for the initial postoperative day. Pharmacy costs were individualized to the procedure: the robotic-assisted and laparoscopic arms of the model included only oral pain medication administered every 6 hours, whereas the abdominal arm included one 30-mg vial for intravenous morphine via patient-controlled analgesia for the initial postoperative day, followed by oral pain medication administered every 6 hours until discharge. Pharmacy costs additionally included a daily stool softener, and assumed 1 dose each of intravenous and oral antiemetics (odansetron and promethazine). Postoperative intravenous fluid estimates were identical between the 3 approaches at 1L for the initial postoperative evening. Estimates for intravenous pharmacy costs were obtained from the Medicare Part B maximum allowable charge, and oral medication costs were derived from the lowest advertised price online [17]. The costs for hospital room and board as
well as transfusion packed red blood cell unit cost were obtained from the hospital billing department. The costs for the purchase and maintenance of the daVinci Surgical System (Intuitive Surgical, Inc.) were based on the daVinci S HD system. Mean purchase price was $1.65 million, with an annual maintenance cost of $149 000 per year for years 2 through 5. For costs data, if only charge rather than cost was available for any item, a standardized conversion ratio of 0.6 was applied. This cost-charge ratio was further varied from 0.2 to 1.0 in the sensitivity analysis [19].
Analysis The decision model was constructed and analyzed with commercially available software (TreeAge Pro Suite 2008; TreeAge Software, Inc., Williamstown, MA) [20]. Two models were analyzed, the Robot Existing model and the Robot Purchase model. The Robot Existing model was defined as a hospital system that currently owns the daVinci Surgical System. We assumed, therefore, that the initial capital investment and the annual maintenance costs were previously fully funded by the institution. Thus, these costs were not included in the model. The Robot Purchase model, in comparison, represented a hospital system that does not currently own a daVinci system and must incur the initial capital investment and recurrent annual maintenance costs for the robotic surgical system. Thus, a total purchase and maintenance cost of $2 246 000 was amortized over 7 years at an interest rate of 5% and distributed to each procedure performed, for which the baseline estimate for the number of procedures per month was 24. The number of procedures per month for this purchased system varied from 4 to 60 in the sensitivity analysis. One-way sensitivity analyses were used to assess the effects of varying each model parameter and cost variables through its range of low and high estimates (Tables 1 and 2). This study was exempt from institutional board review because the research was based on publicly available data.
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Results Existing Robot Model We designed our initial analysis to estimate overall costs for robotic-assisted, laparoscopic, and abdominal sacrocolpopexy, respectively, under the assumption that a daVinci HD S Robotic Surgical System (Intuitive Surgical, Inc.) was already present at the surgical facility. Baseline analysis demonstrated that robotic-assisted sacrocolpopexy was the most expensive, at $8508 per procedure. In comparison, laparoscopic sacrocolpopexy was $7353 per procedure, and abdominal sacrocolpopexy was the least expensive, at $5792 per procedure. When comparing the 2 minimally invasive approaches, our analyses found robotic-assisted sacrocolpopexy to be $1155 more costly than laparoscopic sacrocolpopexy, a differential that was narrowed to $773 when mean operative times were assumed to be identical at 269 minutes. A cost equivalence of $7353 was reached only when robotic-assisted operative time was further decreased below its lowest reported estimate to 149 minutes, a value not reported in the literature, whereas laparoscopic operative time remained at its baseline value of 269 minutes. There were 2 other scenarios in which robotic-assisted sacrocolpopexy became less costly than laparoscopic sacrocolpopexy: robotic disposables were reduced to less than $2132 from the baseline cost of $3293, and laparoscopic disposables were increased to more than $3413 from the baseline cost of $2244. Fig. 2 shows the Tornado diagram, a graphic representation of 1-way sensitivity analyses, comparing robotic-assisted vs laparoscopic sacrocolpopexy [21]. With the exception of the extremes noted above, varying the remaining parameters of LOS, risk of conversion, risk of transfusion, anesthesia costs, surgeon fees, postanesthesia costs, hospital room and board, pharmacy costs, and laboratory costs failed to make the robotic-assisted approach less costly than the laparoscopic approach. When the laparoscopic and abdominal approaches were compared, laparoscopic sacrocolpopexy remained more expensive than abdominal sacrocolpopexy in most analyses. The only scenarios in which laparoscopic sacrocolpopexy became the least expensive were when mean LOS for abdominal sacrocolpopexy was increased to more than 5.6 days and laparoscopic LOS remained fixed at 1.8 days; when the surgeon reimbursement fee for abdominal sacrocolpopexy was increased to more than $2213; and when disposable equipment costs for laparoscopic sacrocolpopexy were lowered to less than $668. Otherwise, the abdominal approach remained less costly than either the robotic-assisted or laparoscopic approach (Tables 1 and 2). Robot Purchase Model For the Robot Purchase model, we assumed the purchase and maintenance of a daVinci HD S Surgical System (Intuitive Surgical, Inc.) amortized over 7 years, in addition to the other costs included in the Robot Existing model. In
Fig. 2. Tornado diagram: laparoscopic sacrocolpopexy (LSC) cost minus robotic-assisted sacrocolpopexy (RSC). One-way sensitivity analyses demonstrate when RSC becomes less expensive than LSC. Variables with greatest effect on model are listed at top and have longest bars. Range of each variable is given. Vertical dotted line represents $0 US dollars, the point at which RSC and LSC are cost-equivalent. When a bar is less than zero, RSC is more expensive than LSC, and when a bar is more than zero, RSC is less expensive than LSC. LOS 5 length of stay; OR 5 operating room.
the baseline analysis of 24 procedures per month, roboticassisted sacrocolpopexy remained the most expensive, at $9962, compared with laparoscopic at $7353 and abdominal at $5792. The laparoscopic and abdominal sacrocolpopexy costs do not change compared with the Robot Existing model because the primary difference with this model was the addition of the daVinci purchase and maintenance costs. When these costs were distributed over 60, 40, and 20 procedures per month in the sensitivity analysis, the robotic-assisted baseline cost of $8508 was incrementally increased by $581, $865, and $1724 per procedure. The results of the sensitivity analyses comparing robotic-assisted and laparoscopic sacrocolpopexy demonstrated no situations in which roboticassisted sacrocolpopexy became less costly than the laparoscopic approach, even when each parameter was varied through its range in sensitivity analyses. Discussion The present study sought to estimate the effect of robotic sacrocolpopexy on healthcare resource usage in comparison with laparoscopic and abdominal sacrocolpopexy. Using this cost-minimization analysis, we synthesized the best data from the current literature with a micro-costing approach. We found that even without inclusion of the purchase and maintenance costs of the daVinci Surgical System, roboticassisted sacrocolpopexy was more costly than either laparoscopic or abdominal sacrocolpopexy, with an incremental cost of $1155 over the laparoscopic approach and $2716 over the abdominal approach. These increased costs reflect the higher disposable equipment costs associated with robotic sacrocolpopexy, and the increased operative time required for performance using this approach. Sensitivity analyses involving robotic sacrocolpopexy demonstrated no situations in which this approach became less costly than the abdominal approach; however, 3 scenarios were identified in which robotic sacrocolpopexy was less costly than laparoscopic sacrocolpopexy, and these serve to highlight the findings for operative time and disposable
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equipment cost. The potential for shorter robotic operative times and lower robotic disposable equipment costs to improve the economic attractiveness of the robotic operative approach illustrates that although substantial reductions in any one particular parameter may be unlikely, continued innovation and technologic advances may result in significant cost savings in robotic gynecologic surgery. With regard to the comparison of laparoscopic and abdominal sacrocolpopexy, sensitivity analyses demonstrated that the abdominal approach was least expensive in most cases. Laparoscopic sacrocolpopexy became least expensive only when mean LOS for abdominal sacrocolpopexy was more than 5.6 days; when surgeon fees for abdominal sacrocolpopexy were increased to more than $2213, which was close to the maximum of its range; and when laparoscopic disposables cost less than $668, which was near the minimum of its range. These situations in which postoperative LOS is increased, physician reimbursement is increased, or instrumentation expense is decreased by 70% are less likely to occur, making the probability of the mean cost for laparoscopic sacrocolpopexy being lower than the mean cost for abdominal sacrocolpopexy remote. Strengths of the present study include our comprehensive literature search, which reflects real-world experience in robotic-assisted, laparoscopic, and abdominal sacrocolpopexy. By including concurrent hysterectomy and other indicated pelvic reconstructive surgical procedures, the model more closely represents actual clinical scenarios faced by practicing gynecologic surgeons and recognizes that complex surgical plans are required to address these patient conditions. In addition, by integrating the lowest and highest parameter estimates reported in the literature, we allowed compensation for inherent differences in surgical practice, thereby improving model robustness. One limitation of this study is that we did not assess the effect of each route of surgery on quality of life. Based on existing data, we assumed that all 3 surgical approaches would be equally effective in treating advanced prolapse. However, the effect of each route of surgery on quality of life was not integrated into the model because these data currently do not exist. For example, the minimally invasive nature of robotic-assisted and laparoscopic approaches may result in less postoperative pain and faster recovery compared with abdominal sacrocolpopexy. Although these benefits are often associated with minimally invasive procedures, quality-of-life data, specifically measured by utilities, are not available for these procedures. Utility data would enable calculation of quality-adjusted life-years and would enable us to perform a cost-effectiveness analysis. Furthermore, we did not assess the effect of each surgical route on societal costs. While our analysis was performed with regard to immediate costs from a healthcare system perspective, incorporation of societal costs including lost productivity and wages may lead to a different outcome. Another limitation is that we did not account for every potential cost that could be incurred during the perioperative period.
For example, our model did not include rare complications such as intraoperative bowel, bladder, or ureteral injury, and readmission because of bowel obstruction, ileus, or infection. However, because these outcomes are rare, they are unlikely to significantly affect the final results of the decision model. Although in both of our models, robotic sacrocolpopexy remained the most costly, clinicians should consider the potential benefits of the robotic-assisted approach on patients, such as decreased blood loss, shorter LOS, and possibly a quicker return to normal activity over an abdominal route [6,8]. Furthermore, the adoption of robotic techniques may expand patient access to a minimally invasive alternative to abdominal sacrocolpopexy. While correction of pelvic organ prolapse using robotic-assisted sacrocolpopexy is comparable to abdominal sacrocolpopexy at 6-week follow-up, prospective trials are needed to determine the long-term equivalence of these surgical outcomes [8]. In addition, quality-of-life data measured using utilities would enable performance of costeffectiveness analysis, and may be an important distinguishing feature between these 3 routes of surgery. Furthermore, comprehensive cost-minimization modeling regarding interdivisional and interdepartmental use of the daVinci Surgical System across a wide spectrum of surgical procedures is required to better understand the full effect of this emerging technology on use of healthcare resources.
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12. Gold MR, Siegel JE, Russell LB, Weinstein MC, editors. Identifying and valuing outcomes. Cost-Effectiveness in Health and Medicine. New York, NY: Oxford University Press; 1996. 13. Paraiso MF, Walters MD, Rackley RR, Melek S, Hugney C. Laparoscopic and abdominal sacral colpopexies: a comparative cohort study. Am J Obstet Gynecol. 2005;192:1752–1758. 14. Rozet F, Mandron E, Arroyo C, et al. Laparoscopic sacral colpopexy approach for genito-urinary prolapse: experience with 363 cases. Eur Urol. 2005;47:230–236. 15. Brubaker L, Cundiff GW, Fine P, et al. Abdominal sacrocolpopexy with Burch colposuspension to reduce urinary stress incontinence. N Engl J Med. 2006;354:1557–1566. 16. Hsiao KC, Latchamsetty K, Govier FE, Kozlowski P, Kobashi KC. Comparison of laparoscopic and abdominal sacrocolpopexy for the treatment of vaginal vault prolapse. J Endourol. 2007;21:926–930.
499 17. Prescription Price Checker; 2009. Available at: http://www.drugstore.com/ pharmacy/drugindex/default.asp?trx51Z5015. Accessed March 14, 2009. 18. Davis JB. Medical Fees in the United States 2008: Nationwide Charges for Medicine, Surgery, Laboratory, Radiology and Allied Health Services. 14th ed. Los Angeles, CA: Practice Management Information Corporation; 2008. 19. Luce BR, Manning WG, Siegel JE, Lipscomb J. Estimating costs in costeffectiveness analysis. In: Gold MR, Siegel JE, Russell LB, Weinstein MC, editors. Cost-Effectiveness in Health and Medicine. New York, NY: Oxford University Press; 1996. p. 196–198. 20. Krahn MD, Naglie G, Naimark D, Redelmeier DA, Detsky AS. Primer on medical decision analysis: part 4, analyzing the model and interpreting the results. Med Decis Making. 1997;17:142–151. 21. Eschenbach TG. Spiderplots versus Tornado diagrams for sensitivity analysis. Interfaces. 1992;22:40–46.
Cost-Minimization Analysis of Robotic-Assisted, Laparoscopic, and Abdominal Sacrocolpopexy John P. Judd, MD*, Nazema Y. Siddiqui, MD, Jason C. Barnett, MD, Anthony G. Visco, MD, Laura J. Havrilesky, MD, and Jennifer M. Wu, MD, MPH From the Divisions of Urogynecology and Pelvic Reconstructive Surgery (Drs. Judd, Siddiqui, Visco, and Wu) and Gynecologic Oncology (Drs. Barnett and Havrilesky), Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina.
ABSTRACT Study Objective: To perform a cost-minimization analysis comparing robotic-assisted, laparoscopic, and abdominal sacrocolpopexy. Design: Cost-minimization analysis using a micro-costing approach (Canadian Task Force classification III). Measurements and Main Results: A decision model was developed to compare the costs (2008 US dollars) of robotic, laparoscopic, and abdominal sacrocolpopexy. Our model included operative time, risk of conversion, risk of transfusion, and length of stay (LOS) for each method. Respective baseline estimates for robotic, laparoscopic, and abdominal sacrocolpopexy procedures included operative time (328, 269, and 170 minutes), conversion (1.4%, 1.8%, and 0%), transfusion (1.4%, 1.8%, 3.8%), and LOS (1.0, 1.8, and 2.7 days). Two models were used, the Robot Existing model, that is, current hospital ownership of a robotic system, and the Robot Purchase model, that is, initial hospital purchase of a robotic system, with purchase and maintenance costs amortized and distributed across robotic procedures. Sensitivity analyses were performed to assess the effect of varying each parameter through its range. For the Robot Existing robot model, robotic sacrocolpopexy was the most expensive, $8508 per procedure compared with laparoscopic sacrocolpopexy at $7353 and abdominal sacrocolpopexy at $5792. Robotic and laparoscopic sacrocolpopexy became cost-equivalent only when robotic operative time was reduced to 149 minutes, robotic disposables costs were reduced to $2132, or laparoscopic disposable costs were increased to $3413. Laparoscopic and abdominal sacrocolpopexy became cost-equivalent only when laparoscopic disposable costs were reduced to $668, mean LOS for abdominal sacrocolpopexy was increased to 5.6 days, or surgeon reimbursement for abdominal sacrocolpopexy exceeded $2213. The addition of robotic purchase and maintenance costs resulted in an incremental increase of $581, $865, and $1724 per procedure when these costs were distributed over 60, 40, and 20 procedures per month, respectively. Conclusion: Robotic sacrocolpopexy was more expensive compared with the laparoscopic or abdominal routes under the baseline assumptions. Journal of Minimally Invasive Gynecology (2010) 17, 493–499 Ó 2010 AAGL. All rights reserved. Keywords:
Cost; Cost analysis; Cost-minimization analysis; Laparoscopic; Robotic; Robotic-assisted; Sacral colpopexy; Sacrocolpopexy
Pelvic organ prolapse is a common condition, resulting in more than 200 000 surgical procedures each year in the United States [1]. It is estimated that 1 in 9 women who live to age 80 The authors have no commercial, proprietary, or financial interest in the products or companies described in this article. Dr. Visco is a proctor and assists with procedure development for Intuitive Surgical, Inc. Presented at the 30th Annual Scientific Meeting of the American Urogynecologic Society, Hollywood, Florida, September 24–26, 2009. Corresponding author: John P. Judd, MD, Division of Urogynecology and Pelvic Reconstructive Surgery, Duke University Medical Center, DUMC 3192, Durham, NC 27710. E-mail: [email protected] Submitted January 3, 2010. Accepted for publication March 6, 2010. Available at www.sciencedirect.com and www.jmig.org 1553-4650/$ - see front matter Ó 2010 AAGL. All rights reserved. doi:10.1016/j.jmig.2010.03.011
years will undergo surgical treatment of prolapse or urinary incontinence [2]. Abdominal sacrocolpopexy is recognized as a well-accepted and durable repair for advanced apical prolapse, with demonstrated long-term success [3,4]. Until recently, sacrocolpopexy required the associated morbidity of an abdominal incision. However, with development of the laparoscopic approach to treatment of sacrocolpopexy, patients experience the benefits of a minimally invasive alternative to laparotomy, including decreased blood loss and shorter hospital stay, with comparable operative time and clinical outcome [5,6]. The advanced laparoscopic surgical skills required for laparoscopic sacrocolpopexy are challenging and may limit use of this procedure. With the implementation of robotic-assisted laparoscopy using the da Vinci Surgical System (Intuitive Surgical, Inc.,
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Fig. 1. Decision model comparing robotic-assisted, laparoscopic, and abdominal sacrocolpopexy, beginning with diagnosis of advanced prolapse.
Sunnyvale, CA), proponents contend that complex laparoscopic maneuvers can be accomplished with less difficulty, simplifying the procedure and shortening operative time [7]. In a recent retrospective study, patients who underwent robotic-assisted sacrocolpopexy experienced similar vaginal vault support results at 6 weeks when compared with patients who underwent abdominal sacrocolpopexy [8]. Furthermore, compared with the abdominal approach, robotic-assisted sacrocolpopexy was associated with less blood loss, similar rates of perioperative complications, and shorter length of hospital stay (LOS), but at the expense of longer operative time. When considering adoption of a new and rapidly evolving technology, an important factor to consider is cost. Recent data have shown that robotic-assisted sacrocolpopexy produces the highest hospital charges when compared with laparoscopic or abdominal sacrocolpopexy, with no significant difference in Medicare reimbursement between the 3 approaches [9]. It is important for any hospital or practice to have a clear understanding of the costs associated with adoption and implementation of a urogynecologic robotic program or expansion of an existing robotic program to include robotic-assisted sacrocolpopexy. Data to minimize healthcare costs while conveying the most benefit to patients are currently lacking. Thus, we performed a costminimization analysis to compare robotic-assisted with laparoscopic and abdominal sacrocolpopexy.
Material and Methods Decision Model To compare the costs of sacrocolpopexy performed using robotic-assisted, laparoscopic, and abdominal techniques, we developed a decision model [10,11]. A decision model is
ideal for a cost analysis because it incorporates both outcomes and costs and enables sensitivity analyses. Our method is based on the guidelines of the Panel on CostEffectiveness in Health and Medicine [12]. This analysis was conducted from a healthcare system perspective and costs were 2008 US dollars. Inasmuch as sacrocolpopexy is performed in a similar fashion regardless of the route of surgery and because the short-term outcomes of roboticassisted, laparoscopic, and abdominal sacrocolpopexy are comparable [5,8,13], we assumed that they were equally effective in the treatment of advanced prolapse. Given this assumption of equivalent outcomes, we focused only on costs and, therefore, conducted a cost-minimization analysis and not a cost-effectiveness analysis. The model was based on a hypothetical cohort of women with advanced pelvic organ prolapse who have elected to undergo surgical correction via sacrocolpopexy with synthetic polypropylene mesh (Fig. 1). Women can opt for a sacrocolpopexy via 1 of 3 routes of surgery: robotic-assisted, laparoscopic, or abdominal. For the robotic-assisted and laparoscopic cohorts, the model included the possibility of conversion to an abdominal procedure. Conversions were defined as ‘‘early,’’ that is, those occurring before robot docking in the roboticassisted group or during the diagnostic portion of the case in the laparoscopic group, or ‘‘late,’’ that is, once hysterectomy or sacrocolpopexy was under way. The risk of blood transfusion was incorporated into all cohorts, with maximum transfusion volume assumed to be 2 units of packed red blood cells. We considered only short-term events that were likely to occur during the initial admission. Because of the rarity of enterotomy or ureteral injury, we chose blood transfusion as the only secondary event for which we calculated cost during the initial hospitalization [3].
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Table 1
Robotic-assisted, laparoscopic, and abdominal sacrocolpopexy parameter estimatesa Robotic-assisted sacrocolpopexy
Laparoscopic sacrocolpopexy
Abdominal sacrocolpopexy
Parameter
Baseline
Range
Baseline
Range
Baseline
Range
Operative time, min Conversion risk, % Transfusion risk, % Length of stay, days
328 [8] 1.4 [8] 1.4 [8] 1 [8]
130 [7]–383 [8] 0–12 [16] 0–5 [3] 0.5–3 [7]
269 [13] 1.8 [13] 1.8 [13] 1.8 [13]
97 [14]–334 [13] 0–12 [16] 0–5 [3] 0.5–3.0 [13]
170 [15] NA 3.8 [8] 2.7 [8]
110 [15]–286 [8] NA 0 [16]–17 [3] 2 [16]–6 [13]
NA 5 data not available. a References given in brackets.
Parameter Estimates
Costs
Parameter estimates were derived from a systematic review of the medical literature. In decision analysis, data for the parameters in the model are often abstracted from a systematic literature search [12]. Estimates from the highest quality studies are then used as the baseline, or base-case, estimates, and the lowest and highest reported values are used for the sensitivity analyses. A PubMed search was performed in February 2009 using the keywords ‘‘Colpopexy,’’ ‘‘Sacral colpopexy,’’ and ‘‘Sacrocolpopexy’’ combined with ‘‘Abdominal,’’ ‘‘Laparoscopic,’’ ‘‘Robotic,’’ or ‘‘Robotic-assisted.’’ This search was limited to human subjects and English, with exclusion of editorials, letters, or comments. Studies with fewer than 20 subjects were excluded, whereas studies in which concomitant procedures including hysterectomy and colporrhaphy were performed were included because they are representative of situations commonly encountered in clinical practice. On the basis of the recommendations of the US Preventive Services Task Force, each identified article was given a hierarchical rank based on study design, with data from higher quality studies such as randomized controlled trials and comparative studies given greater weight than data derived from case series [12]. Because no studies comparing all modes of sacrocolpopexy were identified, data were obtained from 7 observational studies. Two comparative studies, Geller et al [8], representing the largest comparative study of robotic-assisted and abdominal sacrocolpopexy, and Paraiso et al [13], representing the largest comparative study of laparoscopic vs abdominal sacrocolpopexy, reported the highest quality data and, therefore, were the source for many of the parameter estimates in the base-case analysis. Parameter estimates were obtained for operative time, risk of conversion (for laparoscopic and robotic procedures), risk of transfusion, and LOS (Table 1). In determining the ranges of each parameter estimate, the extracted data from the previously identified 7 studies were reviewed, and the highest and lowest estimates determined in such a way as to provide the widest range of potential values (Table 1). Estimates listed without reference were assumptions based on expert opinion; thus, we varied these parameters widely in the sensitivity analyses to ensure model robustness.
Costs in 2008 US dollars were derived using a microcosting approach based on our own institutional data (Table 2). For each procedure, physician reimbursement was derived from current Medicare reimbursement rates for anesthesia CPT code 00840 and surgeon CPT codes 57425 (robotic-assisted and laparoscopic) and 57283 (abdominal) [18]. Procedure costs were derived by examining the perioperative, intraoperative, and postoperative costs incurred at Duke medical center. For all approaches, perioperative and postoperative costs accounted for the cost of time in preoperative holding and the postanesthesia care unit, as well as room and board for the duration of hospital stay. Anesthesiology costs consisted of a base fee of $1413 per procedure that included initial setup and professional fees. Additional costs were then applied based on the operative time required for each approach (Table 2). For intraoperative costs, we accounted for standardized operating room costs including cost per minute of operative time, anesthesia fees per minute, and surgical and anesthesia physician reimbursement (Table 2). In addition, we included disposable costs related to each procedure such as drapes, gowns, and gloves; single-use instruments; sutures; Foley catheter; and miscellaneous items such as the electrosurgical generator, scalpel blades, uterine manipulators, and laparoscopic trocars as indicated. For both robotic-assisted and laparoscopic sacrocolpopexy, we sought to minimize the cost per procedure of disposable instruments. For the robotic-assisted approach, the cost of each reusable robotic instrument was evenly distributed across 10 robotic procedures based on the 10 lives available for each robotic instrument before they must be replaced. Because procedures using laparoscopic and abdominal surgical equipment are now commonplace, we assumed that all hospital systems already own the required surgical equipment for these procedures and, thus, no additional investment was needed for this equipment. Reusable instrumentation for both laparoscopic and abdominal surgery was also assumed to have no cost because of the substantial lifetime of the instrumentation. To estimate the cost of conversion, we assumed that a late conversion from robotic-assisted or laparoscopic sacrocolpopexy to laparotomy would incur the full cost of the current
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496 Table 2
Cost estimates for robotic-assisted, Laparoscopic, and abdominal sacrocolpopexy Robotic-assisted sacrocolpopexy
Laparoscopic sacrocolpopexy
Abdominal sacrocolpopexy
Cost, 2008 US dollars
Baseline
Range
Baseline
Range
Baseline
Anesthesia Professional fee, surgeon Operating room Disposable equipment, early conversion Disposable equipment, late or no conversion Postanesthesia care Room and board, pharmacy [17], laboratory
842 893 2728 1924
334–983 893–4156 1081–3185 NA
690 893 2237 1677
249–857 893–4156 807–2778 NA
436 638 1414 NA
282–734 638–3276 915–2379 NA
3293
1500–4500
2244
500–3500
966
0–2000
216 1198
77–378 468–2748
216 1654
77–378 468–2748
404 2489
102–816 1851–5499
Range
NA 5 not applicable.
surgical approach, along with the cost of the additional operative time required for the conversion. This additional operative time was assumed to be 30 minutes at baseline, with a range of 0 to 60 minutes. Early conversion for robotic-assisted or laparoscopic sacrocolpopexy, however, reverted to the baseline surgical time of abdominal sacrocolpopexy, with an additional amount of operative time required for the initial laparoscopic portion of the procedure and time to convert, again assumed to be 30 minutes. We recognized that fewer laparoscopic instruments would have been used during an early conversion from a robotic-assisted or laparoscopic approach, and disposable costs were calculated appropriately. For early conversion of robotic-assisted sacrocolpopexy, only initial laparoscopic instruments such as graspers and monopolar endoshears were included as disposable equipment. Because the robotic system had not yet been docked, no lives were deducted from the robotic instruments, and, thus, no cost was accrued for the robotic instrumentation. For laparoscopic sacrocolpopexy, there was no difference in disposable equipment use between our early or late conversion arms because all instruments were assumed opened at the beginning of the procedure. To account for postoperative care, laboratory tests including a complete blood cell count and basic metabolic panel were used for the initial postoperative day. Pharmacy costs were individualized to the procedure: the robotic-assisted and laparoscopic arms of the model included only oral pain medication administered every 6 hours, whereas the abdominal arm included one 30-mg vial for intravenous morphine via patient-controlled analgesia for the initial postoperative day, followed by oral pain medication administered every 6 hours until discharge. Pharmacy costs additionally included a daily stool softener, and assumed 1 dose each of intravenous and oral antiemetics (odansetron and promethazine). Postoperative intravenous fluid estimates were identical between the 3 approaches at 1L for the initial postoperative evening. Estimates for intravenous pharmacy costs were obtained from the Medicare Part B maximum allowable charge, and oral medication costs were derived from the lowest advertised price online [17]. The costs for hospital room and board as
well as transfusion packed red blood cell unit cost were obtained from the hospital billing department. The costs for the purchase and maintenance of the daVinci Surgical System (Intuitive Surgical, Inc.) were based on the daVinci S HD system. Mean purchase price was $1.65 million, with an annual maintenance cost of $149 000 per year for years 2 through 5. For costs data, if only charge rather than cost was available for any item, a standardized conversion ratio of 0.6 was applied. This cost-charge ratio was further varied from 0.2 to 1.0 in the sensitivity analysis [19].
Analysis The decision model was constructed and analyzed with commercially available software (TreeAge Pro Suite 2008; TreeAge Software, Inc., Williamstown, MA) [20]. Two models were analyzed, the Robot Existing model and the Robot Purchase model. The Robot Existing model was defined as a hospital system that currently owns the daVinci Surgical System. We assumed, therefore, that the initial capital investment and the annual maintenance costs were previously fully funded by the institution. Thus, these costs were not included in the model. The Robot Purchase model, in comparison, represented a hospital system that does not currently own a daVinci system and must incur the initial capital investment and recurrent annual maintenance costs for the robotic surgical system. Thus, a total purchase and maintenance cost of $2 246 000 was amortized over 7 years at an interest rate of 5% and distributed to each procedure performed, for which the baseline estimate for the number of procedures per month was 24. The number of procedures per month for this purchased system varied from 4 to 60 in the sensitivity analysis. One-way sensitivity analyses were used to assess the effects of varying each model parameter and cost variables through its range of low and high estimates (Tables 1 and 2). This study was exempt from institutional board review because the research was based on publicly available data.
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Results Existing Robot Model We designed our initial analysis to estimate overall costs for robotic-assisted, laparoscopic, and abdominal sacrocolpopexy, respectively, under the assumption that a daVinci HD S Robotic Surgical System (Intuitive Surgical, Inc.) was already present at the surgical facility. Baseline analysis demonstrated that robotic-assisted sacrocolpopexy was the most expensive, at $8508 per procedure. In comparison, laparoscopic sacrocolpopexy was $7353 per procedure, and abdominal sacrocolpopexy was the least expensive, at $5792 per procedure. When comparing the 2 minimally invasive approaches, our analyses found robotic-assisted sacrocolpopexy to be $1155 more costly than laparoscopic sacrocolpopexy, a differential that was narrowed to $773 when mean operative times were assumed to be identical at 269 minutes. A cost equivalence of $7353 was reached only when robotic-assisted operative time was further decreased below its lowest reported estimate to 149 minutes, a value not reported in the literature, whereas laparoscopic operative time remained at its baseline value of 269 minutes. There were 2 other scenarios in which robotic-assisted sacrocolpopexy became less costly than laparoscopic sacrocolpopexy: robotic disposables were reduced to less than $2132 from the baseline cost of $3293, and laparoscopic disposables were increased to more than $3413 from the baseline cost of $2244. Fig. 2 shows the Tornado diagram, a graphic representation of 1-way sensitivity analyses, comparing robotic-assisted vs laparoscopic sacrocolpopexy [21]. With the exception of the extremes noted above, varying the remaining parameters of LOS, risk of conversion, risk of transfusion, anesthesia costs, surgeon fees, postanesthesia costs, hospital room and board, pharmacy costs, and laboratory costs failed to make the robotic-assisted approach less costly than the laparoscopic approach. When the laparoscopic and abdominal approaches were compared, laparoscopic sacrocolpopexy remained more expensive than abdominal sacrocolpopexy in most analyses. The only scenarios in which laparoscopic sacrocolpopexy became the least expensive were when mean LOS for abdominal sacrocolpopexy was increased to more than 5.6 days and laparoscopic LOS remained fixed at 1.8 days; when the surgeon reimbursement fee for abdominal sacrocolpopexy was increased to more than $2213; and when disposable equipment costs for laparoscopic sacrocolpopexy were lowered to less than $668. Otherwise, the abdominal approach remained less costly than either the robotic-assisted or laparoscopic approach (Tables 1 and 2). Robot Purchase Model For the Robot Purchase model, we assumed the purchase and maintenance of a daVinci HD S Surgical System (Intuitive Surgical, Inc.) amortized over 7 years, in addition to the other costs included in the Robot Existing model. In
Fig. 2. Tornado diagram: laparoscopic sacrocolpopexy (LSC) cost minus robotic-assisted sacrocolpopexy (RSC). One-way sensitivity analyses demonstrate when RSC becomes less expensive than LSC. Variables with greatest effect on model are listed at top and have longest bars. Range of each variable is given. Vertical dotted line represents $0 US dollars, the point at which RSC and LSC are cost-equivalent. When a bar is less than zero, RSC is more expensive than LSC, and when a bar is more than zero, RSC is less expensive than LSC. LOS 5 length of stay; OR 5 operating room.
the baseline analysis of 24 procedures per month, roboticassisted sacrocolpopexy remained the most expensive, at $9962, compared with laparoscopic at $7353 and abdominal at $5792. The laparoscopic and abdominal sacrocolpopexy costs do not change compared with the Robot Existing model because the primary difference with this model was the addition of the daVinci purchase and maintenance costs. When these costs were distributed over 60, 40, and 20 procedures per month in the sensitivity analysis, the robotic-assisted baseline cost of $8508 was incrementally increased by $581, $865, and $1724 per procedure. The results of the sensitivity analyses comparing robotic-assisted and laparoscopic sacrocolpopexy demonstrated no situations in which roboticassisted sacrocolpopexy became less costly than the laparoscopic approach, even when each parameter was varied through its range in sensitivity analyses. Discussion The present study sought to estimate the effect of robotic sacrocolpopexy on healthcare resource usage in comparison with laparoscopic and abdominal sacrocolpopexy. Using this cost-minimization analysis, we synthesized the best data from the current literature with a micro-costing approach. We found that even without inclusion of the purchase and maintenance costs of the daVinci Surgical System, roboticassisted sacrocolpopexy was more costly than either laparoscopic or abdominal sacrocolpopexy, with an incremental cost of $1155 over the laparoscopic approach and $2716 over the abdominal approach. These increased costs reflect the higher disposable equipment costs associated with robotic sacrocolpopexy, and the increased operative time required for performance using this approach. Sensitivity analyses involving robotic sacrocolpopexy demonstrated no situations in which this approach became less costly than the abdominal approach; however, 3 scenarios were identified in which robotic sacrocolpopexy was less costly than laparoscopic sacrocolpopexy, and these serve to highlight the findings for operative time and disposable
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equipment cost. The potential for shorter robotic operative times and lower robotic disposable equipment costs to improve the economic attractiveness of the robotic operative approach illustrates that although substantial reductions in any one particular parameter may be unlikely, continued innovation and technologic advances may result in significant cost savings in robotic gynecologic surgery. With regard to the comparison of laparoscopic and abdominal sacrocolpopexy, sensitivity analyses demonstrated that the abdominal approach was least expensive in most cases. Laparoscopic sacrocolpopexy became least expensive only when mean LOS for abdominal sacrocolpopexy was more than 5.6 days; when surgeon fees for abdominal sacrocolpopexy were increased to more than $2213, which was close to the maximum of its range; and when laparoscopic disposables cost less than $668, which was near the minimum of its range. These situations in which postoperative LOS is increased, physician reimbursement is increased, or instrumentation expense is decreased by 70% are less likely to occur, making the probability of the mean cost for laparoscopic sacrocolpopexy being lower than the mean cost for abdominal sacrocolpopexy remote. Strengths of the present study include our comprehensive literature search, which reflects real-world experience in robotic-assisted, laparoscopic, and abdominal sacrocolpopexy. By including concurrent hysterectomy and other indicated pelvic reconstructive surgical procedures, the model more closely represents actual clinical scenarios faced by practicing gynecologic surgeons and recognizes that complex surgical plans are required to address these patient conditions. In addition, by integrating the lowest and highest parameter estimates reported in the literature, we allowed compensation for inherent differences in surgical practice, thereby improving model robustness. One limitation of this study is that we did not assess the effect of each route of surgery on quality of life. Based on existing data, we assumed that all 3 surgical approaches would be equally effective in treating advanced prolapse. However, the effect of each route of surgery on quality of life was not integrated into the model because these data currently do not exist. For example, the minimally invasive nature of robotic-assisted and laparoscopic approaches may result in less postoperative pain and faster recovery compared with abdominal sacrocolpopexy. Although these benefits are often associated with minimally invasive procedures, quality-of-life data, specifically measured by utilities, are not available for these procedures. Utility data would enable calculation of quality-adjusted life-years and would enable us to perform a cost-effectiveness analysis. Furthermore, we did not assess the effect of each surgical route on societal costs. While our analysis was performed with regard to immediate costs from a healthcare system perspective, incorporation of societal costs including lost productivity and wages may lead to a different outcome. Another limitation is that we did not account for every potential cost that could be incurred during the perioperative period.
For example, our model did not include rare complications such as intraoperative bowel, bladder, or ureteral injury, and readmission because of bowel obstruction, ileus, or infection. However, because these outcomes are rare, they are unlikely to significantly affect the final results of the decision model. Although in both of our models, robotic sacrocolpopexy remained the most costly, clinicians should consider the potential benefits of the robotic-assisted approach on patients, such as decreased blood loss, shorter LOS, and possibly a quicker return to normal activity over an abdominal route [6,8]. Furthermore, the adoption of robotic techniques may expand patient access to a minimally invasive alternative to abdominal sacrocolpopexy. While correction of pelvic organ prolapse using robotic-assisted sacrocolpopexy is comparable to abdominal sacrocolpopexy at 6-week follow-up, prospective trials are needed to determine the long-term equivalence of these surgical outcomes [8]. In addition, quality-of-life data measured using utilities would enable performance of costeffectiveness analysis, and may be an important distinguishing feature between these 3 routes of surgery. Furthermore, comprehensive cost-minimization modeling regarding interdivisional and interdepartmental use of the daVinci Surgical System across a wide spectrum of surgical procedures is required to better understand the full effect of this emerging technology on use of healthcare resources.
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