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Minimally invasive hepatopancreatobiliary surgery in North America: an ACS-NSQIP analysis of predictors of conversion for laparoscopic and robotic pancreatectomy and hepatectomy
Correspondence: Amer H. Zureikat, Department of Surgery, Division of Surgical Oncology, University of Pittsburgh Medical Center, 5150 Centre Avenue Suite 421, Pittsburgh, PA 15232, USA.
American College of Surgeons – National Surgical Quality Improvement Program, Chicago, IL, USADepartment of Surgery and Olin Business School, Washington University in St Louis, St Louis, MO, USABJC Healthcare, St Louis, MO, USA
Procedural conversion rates represent an important aspect of the feasibility of minimally invasive surgical (MIS) approaches. This study aimed to outline the rates and predictors of procedural completion/conversion for MIS hepatectomy and pancreatectomy.
Methods
All 2014 ACS-NSQIP laparoscopic and robotic hepatectomy and pancreatectomy procedures were identified and grouped into pure, open assist, or unplanned conversion to open. Risk adjusted multinomial logistic regression models were generated with completion (Pure) set as the primary outcome.
Results
1667 (laparoscopic = 1360, robotic = 307) resections were captured. After risk adjustment, robotic DP was associated with similar open assist (relative risk ratio −1.9%, P = 0.602), but lower unplanned conversion (−8.2%, P = 0.004) and open assist + unplanned conversion (−10.1%, P = 0.015) compared to laparoscopic DP; while robotic PD was associated with lower open assist (−22.2%, P < 0.001), unplanned conversions (−15%, P = 0.006) and open assist + unplanned conversions (−37.2, P < 0.001) compared to laparoscopic PD. The robotic and laparoscopic approaches to hepatectomy were not associated with differences in pure MIS completion rates (P = NS) after risk adjustment.
Conclusions
The robotic approach to pancreatectomy was associated with higher rates of pure MIS completion compared to laparoscopy, whereas no difference in MIS completion rates was noted for robotic versus laparoscopic hepatectomy.
Introduction
Laparoscopic and robotic surgery are currently the two most widely used minimally invasive surgical (MIS) platforms. Despite multiple reports of safety and feasibility, debate continues on the role and advantages of either approach in Hepato-Pancreato-Biliary (HPB) surgery.
Proponents of laparoscopic approaches cite increased costs, longer operative times and inefficient use of operating room resources, without any clear benefit in outcomes for the robotic approach. Advocates of the robotic platform value stereoscopic vision, platform stability, and wristed instruments as critical assets, and cite their absence as obstacles to the dissemination of pure laparoscopy for complex HPB resections. Advantages of either approach have been difficult to ascertain, since comparative effectiveness studies to date are limited to either small retrospective studies or large national datasets that fail to differentiate operative approach, and lack sufficient granularity to allow for adequate risk adjustment.
Feasibility is a central issue to the adoption of a surgical platform. The strength of any recommendation related to surgical approach couples an assessment of feasibility (ease and efficiency in application) and added benefit compared to other approaches. A metric that can shed light on the successful application –and therefore feasibility-of either laparoscopic or robotic approach to HPB surgery is the procedural completion rate; defined as the ability to complete an intended HPB procedure in minimally invasive fashion. HPB procedure data on minimally invasive (laparoscopic or robotic) procedural completion, use of open (hand) assistance, and unplanned conversion to open, have recently become available through the American College of Surgeons –National Surgical Quality Improvement Program (ACS-NSQIP) Procedure Targeted Hepatectomy and Pancreatectomy modules. Data obtained from the Procedure Targeted Participant User File include procedure specific variables that are unique to both pancreatectomy and hepatectomy, allowing for risk stratified outcome assessments of various operative approaches to HPB procedures.
The aim of this analysis was to provide a current assessment of laparoscopic and robotic approaches to HPB surgery in North America, focusing on predictors of MIS completion, open assistance, and unplanned conversion to open. The hypothesis was that the robotic platform's unique characteristics might allow for a greater rate of completion of minimally invasive hepatectomy and pancreatectomy compared to standard laparoscopic approaches.
Materials and methods
Data collection and definitions
Patients who underwent a hepatectomy or pancreatectomy were identified from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) 2014 hepatectomy and pancreatectomy targeted participant use data file (PUF). Unlike the general PUF which samples cases according to a validated algorithm, the procedure targeted PUF contains additional variables that allow for enhanced risk adjustment, and samples all hepatectomies and pancreatectomies at participating institutions. The 2014 Procedure Targeted Hepatectomy PUF contains 3064 procedures from 92 hospitals (USA 88, non-USA 4), and the 2014 Procedure Targeted Pancreatectomy PUF contains 5187 procedures from 106 (USA 103, non-USA 3) hospitals. All variables were as defined and specified within the ACS NSQIP.
Four types of HPB procedures were identified by primary Current Procedural Terminology (CPT; copyright AMA) code: partial hepatectomy (PH = resection of <3 hepatic segments; CPT 47120), major hepatectomy (MH = resection of ≥3 hepatic segments; CPTs 47,122, 47,125, and 47,130), distal pancreatectomy (DP; CPTs 48,140 and 48,146), and pancreaticoduodenectomy (PD; CPTs 48,150, 48,152, 48,153, and 48,154). The “Operative Approach” variable was classified as Open, Laparoscopic, Robotic, or Other (NOTES/SILS/etc.). Within the Laparoscopic and Robotic approaches, “Operative Outcome” was classified as “Pure” (procedure completed in pure minimally invasive fashion without open assistance or/unplanned conversion to open), “Open Assist” (OA), or “Unplanned Conversion to Open” (UCO).
Patient variables used for risk adjustment
Relevant preoperative and intraoperative variables for risk-adjustment were identified from the PUF. All variables are defined and specified in the ACS-NSQIP. Variables collected for all procedures included demographics (Age, Sex, BMI, Transfer Status, Elective Surgery), comorbidities (Primary ICD-9 Diagnosis, ASA Classification, Diabetes, Current Smoker, Dyspnea, History of COPD, Hypertension, Disseminated Cancer, Steroid Use, Weight Loss, and Bleeding Disorder), and laboratory values (Sodium, BUN, Creatinine, Albumin, Bilirubin, SGOT, ALP, WBC, HCT, Platelet, PTT, and INR). Procedure Targeted Hepatectomy variables (pertaining to PH and/or MH) included Trisegmentectomy (CPT 47122), Biliary Stent, Neoadjuvant Therapy, Viral Hepatitis, Liver Texture, Concurrent Partial Resections, Concurrent Ablation, Pringle Maneuver, and Biliary Reconstruction. Procedure Targeted Pancreatectomy variables (pertaining to DP and/or PD) included Pylorus-preservation for PDs (CPTs 48,153 and 48,154), Jaundice, Biliary Stent, Chemotherapy, Radiotherapy, Duct Size, Gland Texture, and Vascular Resection. Prior to analysis, continuous variables were binned according to commonly-accepted cutoffs.
Statistical analysis
Multinomial logistic regression models were built to assess the relationships between risk-adjusted variables and operative outcome. These models were used to allow all three possible outcomes (Pure, OA, and UCO) to be treated as mutually exclusive, since the intent of the surgeon with regards to planned OA was unknown. For example, whereas an UCO represents the intent of the surgeon to have performed the procedure in MIS fashion, it is difficult to ascertain whether OA procedures (hand assistance, creation of a ‘mini laparotomy’ for reconstruction, or so called ‘hybrid’ open/MI procedures for example) were planned a priori or represent an unexpected need for open assistance.
To select the risk factors for inclusion in each model, a forward stepwise procedure was employed: initial models contained only operative approach (laparoscopic versus robotic) as a risk predictor, and variables were added or removed one at a time. The selection criterion used was Hansen and Yu's Generalized Minimum Description Length (gMDL) criterion, which attempts to balance model goodness-of-fit and parsimony through maximum data compression. Relative-risk ratios (RRR) were then calculated. Relative risks are ratios of a particular operative outcome between two risk factor categories, and RRRs are ratios of relative risks between operative outcomes. An RRR <1 translates to a decreased relative risk compared to the base outcome (Pure, in this case), and an RRR > 1 translates to an increased relative risk compared to the base outcome.
The models were used to calculate robotic vs. laparoscopic contrasts of predictive margins for each procedure type. These contrasts test whether predicted operative outcome probabilities significantly differ (p < 0.05) between the robotic and laparoscopic procedures given equal values for all other risk predictors. Contrasts were performed for OA, UCO, and OA+UCO, with pure set as the base outcome. Risk-adjusted contrasts were compared with non-risk-adjusted contrasts. All analyses were performed using Stata 13.1 (StataCorp LP, College Station, TX, USA).
Results
A total of 7783 procedures were identified from the 2014 NSQIP Hepatectomy and Pancreatectomy Procedure Targeted Participant Use File (Table 1): 1882 PHs; 1182 MHs; 1582 DPs; 3137 PDs. Of these, 6078 (78.1%) were open; 1360 (17.5%) were laparoscopic; 307 (3.9%) were robotic; and 38 (0.5%) were classified as ‘other’. After excluding ‘open’ and ‘other’ approaches, 1667 (laparoscopic = 81.6%, robotic = 18.4%) MI procedures were analyzed. DP was the most common HPB procedure attempted using the laparoscopic or robotic platform (N = 741, 44.5%) whereas MH was the least (N = 144, 8.6%). Although all 4 procedures were more commonly approached laparoscopically, PD had the highest proportion of robotic procedures (N = 88; 43.8% of all MIS PDs), whereas only 7 (4.9%) MHs were approached robotically.
Table 1Operative approach for 7783 HPB procedures in 2014 NSQIP PUF
Risk unadjusted operative outcomes (Pure, OA, and UCO) by approach are displayed in Table 2. PH had the highest completion (pure) rate (64%) and PD had the highest total UCO proportion (24.4%). In comparison to laparoscopic PH, robotic PHs exhibited no difference in Pure completion rates (57.1% vs 64.6%, P = 0.340), but higher OA (40.5% vs. 19.7%, P = 0.003) and lower UCO rates (2.4% vs. 15.8%, P = 0.005). Due to the low numbers of MHs captured (Lap = 138, Robotic = 7), MH's were excluded from further analyses. Robotic DPs showed a higher Pure completion rate (67.1% vs 56.9%, P = 0.017), no significant difference in OA rates (22.9% vs. 24.9%, P = 0.61), and significantly lower UCO proportion (10.0% vs. 18.2%, P = 0.008) compared to Laparoscopic DPs, whereas Robotic PDs showed higher Pure completions (79.5% vs 39.8%, P < 0.001), and lower rates OA (5.7% vs. 28.3%, P < 0.001) and UCOs (14.8% vs. 31.9%, P = 0.004) compared to Laparoscopic PDs.
Table 2Operative outcome (Pure completion, Open assist, Unplanned Conversion to open) by operative approach (laparoscopic or robotic) for 1667 HPB procedures
Risk-adjusted multivariable models for each operative outcome are presented in Table 3. For PH, the robotic approach (compared to laparoscopy) showed a significantly higher RRR for OA (RRR = 2.497, CI 1.29–4.8, p = 0.006) but not UCO (RRR = 0.181, CI 0.023–1.43, P = 0.105). Other predictors of OA for PH were resection >1 segment, concurrent ablation, hypertension, and elevated SGOT, while concurrent ablation, use of pringle maneuver, and hypertension predicted UCO. For DP, only operative approach was found to influence operative outcomes: the robotic approach was associated with a reduction in UCO (RRR = 0.466, CI 0.267–0.812, P = 0.007) compared to laparoscopic. For PD, the robotic approach was associated with reductions in OA (RRR = 0.1, CI 0.032–0.304, P < 0.001) and UCO (RRR = 0.213, CI 0.094–0.484, P < 0.001). Additionally, use of preoperative radiation was associated with increased OA, while pylorus preservation, concomitant vascular resection, and hypertension were associated with increased UCO during PD.
Table 3Multivariable models for predictors of open assistance or unplanned conversion to open
Finally, risk-adjusted and non-risk-adjusted contrasts of predictive margins for each Operative Type are displayed in Table 4 and Fig. 1. Robotic PH procedures showed a significant risk-adjusted OA increase (21.4%; p = 0.003), UCO decrease (−13.2%; p < 0.001), but no difference in OA+UCO contrast (7.4%, P = 0.349) compared to Laparoscopic PH procedures. Robotic DP procedures showed a significant non-risk-adjusted UCO decrease (−8.2%; p = 0.004) and significant non-risk-adjusted OA+UCO decrease (−10.1%; p = 0.015) compared to Laparoscopic DP procedures. Notably, DP did not have risk-adjusted contrasts because no additional risk factors other than Operative Approach were selected into its model. Robotic PD procedures showed a significant risk-adjusted OA decrease (−22.2%; p < 0.001), UCO decrease (−15.0%; p = 0.006), and OA+UCO decrease (−37.2%; p < 0.001) compared to Laparoscopic PD procedures.
Table 4Risk-adjusted and un-adjusted contrasts of predictive margins for robotic and laparoscopic HPB procedures
Figure 1Risk-adjusted contrasts of predictive margins for robotic and laparoscopic A-partial hepatectomy, B-distal pancreatectomy, C-pancreatoduodenectomy
This report is an overview of the current status of laparoscopic and robotic HPB surgery in North America, focusing on rates and predictors of procedural completion (Pure), use of open assistance (OA), and unplanned conversion to laparotomy (UCO). Our findings indicate that the laparoscopic and robotic platforms are utilized in nearly a fifth of all HPB cases (if the NSQIP case accrual at the involved institutions is generalizable). The robotic approach was associated with lower risk adjusted rates of UCO for partial hepatectomy, distal pancreatectomy and pancreaticoduodenectomy. When assessing OA+UCO as a singular outcome, no difference was noted for robotic and laparoscopic approaches to hepatectomies, while a significant decrease in OA+UCO was noted for robotic pancreatectomies compared to their laparoscopic counterpart.
For minimally invasive hepatic resections, this study suggests that the robotic approach is associated with increased rates of OA, but lower rates of UCO for PH. Low conversion rates for robotic PH have been previously reported.
In a comparison of robotic (n = 57) and laparoscopic (n = 114) hepatectomy, Tsung et al. noted a significantly higher ‘pure completion’ rate (defined as completion in the absence of hand assistance, hybrid procedures, or conversions) for the robotic group (93% vs 49%, P < 0.001); a finding that extended for both major (81% vs 7%, P < 0.001) and minor hepatectomies (100% vs 75%, P = 0.013).
Although our dataset did not contain information on the anatomic location of PHs, the robotic platform's wristed instruments may facilitate resection of the more difficult-to-access posterior hepatic segments, thereby averting the need for conversion. A recent comparison of robotic and laparoscopic hepatectomy by Troisi et al., for example, suggests an improved parenchymal preservation rate for the robotic platform (55% vs 34.1%, p = 0.019), while a second comparison by Tranchart et al. indicates that the robotic platform may be associated with a higher rate of superior and posterior segmental resections (50% versus 11%, p = 0.003) compared to straight laparoscopy.
Despite these differences, when combining OA+UCO as a singular outcome, the type of minimally invasive approach was not an independent predictor of MIS completion for PH.
This analysis suggests that the robotic approach to pancreatectomy is associated with higher completion rates. For DP, although OA was not different between both approaches, the robotic approach was independently protective of UCO, and when combining UCO+OA as a singular outcome, the robotic approach was associated with a near 10% increase in pure completions compared to laparoscopy. Daouadi et al. compared robotic to laparoscopic DP and found the former to be associated with a reduced conversion rate (0% versus 16%, P < 0.05) despite having more pancreatic cancers in the robotic DP group (43% vs 15%, P < 0.05), although other series have not corroborated these findings.
For PD, the effect was more pronounced, with robotic PD displaying a near 22% decrease in OA and 15% decrease in UCO; a resultant 37% increase in pure completions compared to LPD.
Predictably, this study confirms that open surgery remains the more common approach for hepatectomies and pancreatectomies today. Although minimally invasive approaches to HPB procedures were first reported nearly two decades ago, their adoption has been slow. Potential reasons for this tempered enthusiasm include concerns over their safety and oncologic efficacy, coupled with recent reports suggesting marked improvements in outcomes of contemporary open surgery -particularly at high volume centers-over the last three decades.
These factors likely explain why ‘minor HPB resections’ (PH and DP) were more commonly approached in MIS fashion compared to MH and PD in this dataset; the latter cases are technically more challenging, require longer learning curves, and are associated with greater morbidity.
Interestingly, when examining the two ‘minor’ HPB procedures (DP and PH), surgeons were found to attempt an MIS approach for DP more frequently than PH (47% versus 31%, P < 0.001). This relatively low rate of PH may be related to the perceived difficulty in accessing posterior hepatic segments using the minimally invasive approach; a consensus statement on the application of laparoscopy to liver resections advocated its use for readily accessible anterior and inferior segmental lesions (segments II–VI), as opposed to the technically challenging resections of segment I, VII and VIII.
Additionally, whereas open PH is typically associated with minimal morbidity, open DP can still be associated with significant morbidity prompting surgeons to employ MIS in an attempt to improve DP outcomes.
Laparoscopic distal pancreatectomy for pancreatic ductal adenocarcinoma: time for a randomized controlled trial? Results of an all-inclusive national observational study.
The laparoscopic approach to distal pancreatectomy for ductal adenocarcinoma results in shorter lengths of stay without compromising oncologic outcomes.
Other notable findings in this report include the more frequent use of the laparoscopic platform for DP compared to robotics. The lack of reconstruction needed in DP, coupled to comparative effectiveness studies supporting the safety, efficacy and advantages of the laparoscopic approach over its open counterpart may have led surgeons to infer that robotics ‘does not add much’ to standard laparoscopy for this procedure.
Laparoscopic distal pancreatectomy for pancreatic ductal adenocarcinoma: time for a randomized controlled trial? Results of an all-inclusive national observational study.
The laparoscopic approach to distal pancreatectomy for ductal adenocarcinoma results in shorter lengths of stay without compromising oncologic outcomes.
Early national experience with laparoscopic pancreaticoduodenectomy for ductal adenocarcinoma: a comparison of laparoscopic pancreaticoduodenectomy and open pancreaticoduodenectomy from the National Cancer Data Base.
At this time, this study suggests that laparoscopic DP remains the most widely attempted of the 4 HPB procedures.
Although PD was also more commonly approached laparoscopically than robotically, the difference was less marked than for DP. This finding may reflect the perception that the robotic platform's stereoscopic vision and wristed instruments are better suited to facilitate the technically challenging reconstruction needed for PD. Regardless of approach, this study confirms that minimally invasive PD remains uncommon (6.4% of all PD cases). Two reports from the National Cancer Data Base outlined increased 30-day mortality and no improvement in time to adjuvant chemotherapy (for pancreatic cancer) for minimally invasive PD compared to the open approach.
Minimally invasive pancreaticoduodenectomy does not improve use or time to initiation of adjuvant chemotherapy for patients with pancreatic adenocarcinoma.
More recently, however, a risk adjusted comparison of open versus robotic PD was performed at 8 high volume centers, showing both approaches to be comparable with respect to 90 day morbidity, mortality, and oncologic surrogate markers of margin status and lymph node yield.
With such conflicting results over its safety and oncologic efficacy, minimally invasive PD remains unpopular among surgeons today.
This report is limited by a number of factors, foremost of which is a small sample size for certain procedures such as MH. Since the ACS-NSQIP Procedure Targeted Hepatectomy and Pancreatectomy PUF data were first published in 2014, this analysis was limited to a one-year time frame. Second, although this report suggests the robotic approach to be associated with increased completion rates -particularly for pancreatectomies-the impact of this finding on postoperative outcomes remains unknown. To date, a correlation between conversions and postoperative morbidity has not been shown. Conversions however, have been associated with greater intraoperative blood loss and longer operative times; potential surrogates for morbidity, LOS, readmissions, and diminished survival in large series. Whether converted cases portend poorer outcomes –or negate the beneficial effects of MIS- remains to be seen; this work focused on feasibility, and not the full balanced equation of feasibility and potential benefit. Another potential limitation was the use of multinomial logistic regression to identify predictors of different classes of operative outcome. Although using three mutually exclusive outcomes may have reduced sample size and limited the magnitude of conclusions drawn, dichotomizing the outcome to Pure versus OA+UCO could have introduced significant investigator bias. Finally, this analysis is restricted to ACS-NSQIP participating institutions, and may thus be associated with a potential for bias, clustering of data, and lack of generalizability.
Conclusions
Minimally invasive surgical approaches to HPB resections remain in the minority, with the majority of surgeons performing these procedures in open fashion. Among all MIS-HPB procedures sampled, the laparoscopic approach is currently more commonly utilized than its robotic counterpart. After risk adjustment, this study suggests the robotic approach to be associated with an increased ability to perform DP and PD in pure minimally invasive fashion. These insights on feasibility may enhance the risk-versus-benefit assessment of both approaches and facilitate shared decision making.
Funding
None.
Conflicts of interest/disclosures
None.
References
Montalti R.
Berardi G.
Patriti A.
Vivarelli M.
Troisi R.I.
Outcomes of robotic vs laparoscopic hepatectomy: a systematic review and meta-analysis.
Laparoscopic distal pancreatectomy for pancreatic ductal adenocarcinoma: time for a randomized controlled trial? Results of an all-inclusive national observational study.
The laparoscopic approach to distal pancreatectomy for ductal adenocarcinoma results in shorter lengths of stay without compromising oncologic outcomes.
Early national experience with laparoscopic pancreaticoduodenectomy for ductal adenocarcinoma: a comparison of laparoscopic pancreaticoduodenectomy and open pancreaticoduodenectomy from the National Cancer Data Base.
Minimally invasive pancreaticoduodenectomy does not improve use or time to initiation of adjuvant chemotherapy for patients with pancreatic adenocarcinoma.
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