Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair

Comprehensive Learning Curve Analysis of a Long-Term Experience With Thoracic Endovascular Aneurysm Repair

PURPOSE

To analyze the learning curve for thoracic endovascular aortic repair (TEVAR) in a single center over a period of 25 years.

MATERIALS AND METHODS

In total, 390 consecutive standard TEVAR procedures undertaken between 1996 and 2021 were included in a retrospective, observational, single-center study. Cumulative sum charts were elaborated for the entire center experience (primary outcome) as well as for the first and second implanting physicians. Data on procedural variables (contrast volume, operative and fluoroscopy time), 30-day major adverse events (MAEs) and clinical success, and endoleak and reintervention rates were secondary outcomes and subdivided into 4 quartiles of experience (Q1-Q4) or presented as first 2 versus latest 2 quartiles (Q1-Q2 vs Q3-Q4).

RESULTS

The mean follow-up was 4.3±4.0 years. The center's learning curve was achieved after 75 procedures, and it was similar for the first implanting physician. The surgeon coming thereafter had a significantly shorter curve (10 TEVARs). Comparing Q1-Q2 with Q3-Q4, 30-day MAEs (16.1 vs 11.3%, p=0.164), 30-day mortality (11.4% vs 3.6%, p=0.003), and intraoperative additional maneuvers (21.5% vs 13.3%, p=0.033) were reduced along with an improvement in clinical success (85.9% vs 90.3%, p=0.190). From Q1 to Q4, operative time (139.8±65.5 to 76.7±43.7 min, p=0.001), fluoroscopy time (15.1±8.8 to 7.1±5.1 min, p<0.001), and contrast volume (244.0±112.1 to 104.3±46.1 mL, p<0.001) showed a considerable reduction. Late endoleak and aortic-related mortality declined significantly from Q1-Q2 to Q3-Q4 (24.1% to 15.5%, p=0.033 and 18.6% vs 8.2%, p=0.006, respectively). Operative time (p=0.021), contrast volume (p=0.016), and fluoroscopy time (p=0.004) were independent risk factors for endoleak, causing a 1.3-fold risk increase for both each 60 minutes of additional operative time (p=0.021) and every 100 mL of additional contrast medium (p=0.016). Each 10-minute increase in fluoroscopy time determined a 1.4-fold risk increment (p=0.004).

CONCLUSION

The learning curve shortened significantly over time with non-negligible clinical outcome improvements, suggesting that specific endovascular training is mandatory to become an effective TEVAR performer.

CLINICAL IMPACT

For the first time in literature, the standard TEVAR's learning curve has been evaluated at a single vascular surgery center over a period of 25 years. The learning curve for the center and the first physician historically undertaking TEVAR was achieved at the 75th treated patient. The learning curve of the surgeons coming thereafter was significantly shorter (10 cases). This quarter-century demonstrated that intraoperative learning-related variables were associated with long-term clinical outcomes and all have improved over time. Centers approaching TEVAR for the first time and training program providers could use these data to aim to offer better clinical outcomes.

Learning Curve and Long-Term Outcomes of Thoracic Endovascular Repair With the Relay Stent-Graft

PURPOSE

To define the learning curve of a widely employed stent-graft for thoracic endovascular repair (TEVAR) by analyzing procedural variables and their impact on long-term outcomes.

MATERIALS AND METHODS

Standard TEVARs for each major aortic thoracic disease were included excluding procedures using thoracoabdominal, arch fenestrated/branched devices and/or chimneys. The primary outcome was the learning curve analysis using the cumulative sum chart method. The secondary outcomes, presented as early (Q1-Q2) versus latest (Q3-Q4) quartiles of experience, were 30-day major adverse events (MAEs); procedural details (additional maneuvers, operative and fluoroscopy time, and contrast volume); 30-day clinical success; endoleak; aorta-related reintervention; and overall and aorta-related survival.

RESULTS

Between November 2005 and September 2021, 220 consecutive TEVAR procedures involving the Relay endograft (Terumo Aortic, Sunrise, FL, USA) were performed and included in the present analysis. The mean follow-up was 4.5 ± 3.9 years. The learning curve was reached after 10 patients. Secondary outcomes improved significantly over experience. Thirty-day MAE occurrence was 14.5% versus 11.8% (p=0.550). Additional maneuvers (p=0.009), access-vessel additional maneuvers (p=0.010), operative time (p=0.004), Relay Plus (p=0.001), and implantation of multiple stent-grafts (p=0.034) were independent risk markers for MAEs. Operative time (125.9 ± 66.7 vs 86.7 ± 48.5 minutes, p<0.001), contrast volume (185.4 ± 112.8 vs 140.5 ± 88.2 mL, p=0.003), and fluoroscopy time (12.4 ± 12.7 vs 8.8 ± 7.5 minutes, p=0.017) decreased significantly. Late endoleak occurrence was 19.5% with a nonsignificant reduction (21.8% vs 17.3%, p=0.395). Fluoroscopy time (hazard ratio [HR]=1.0; 95% confidence interval [CI]=1.0-1.1; p=0.008), contrast volume (HR=1.0; 95% CI=1.0-1.1; p=0.018), and type III aortic arch (HR=3.3; 95% CI=1.7-6.4; p<0.001) were independent risk markers for endoleak. Fluoroscopy time (HR=1.0; 95% CI=1.0-1.1; p=0.032) and type III aortic arch (HR=3.6; 95% CI=1.7-7.4; p=0.001) confirmed their significant association in a multivariable analysis.

CONCLUSION

In a high-volume center with a consistent previous endovascular experience, the Relay graft presented satisfactory long-term results with a short learning curve supporting its reliability.

CLINICAL IMPACT

The manuscript addresses the understanding of how many TEVAR procedures with a currently implanted device have been required to reach the learning curve for an endovascular skilled center. Our TEVAR experience with the Relay stent-graft (Terumo Aortic) demonstrated that ten implantations were required to achieve the device-related learning curve. The fifteen-year analyzed period showed that intraoperative learning-related variables were associated with long-term clinical outcomes and both improved over time. The Relay stent-graft presented satisfactory long-term results along with a short learning curve in a high-volume endovascular center supporting its ongoing implantation.

Endovascular aneurysm repair offers a survival advantage and is cost-effective compared with conservative management in patients physiologically unfit for open repair

OBJECTIVE

The endovascular aneurysm repair-2 (EVAR-2) trial suggested that EVAR in patients unfit for open surgical repair (OSR) failed to provide a significant overall survival advantage compared with conservative management. The aim is to compare survival and cost-effectiveness in patients with poor cardiopulmonary exercise test (CPET) metrics who underwent EVAR or were managed conservatively.

METHODS

A prospective database of all CPETs (1435 patients) performed to assess preoperative fitness for abdominal aortic aneurysm repair was maintained. A total of 350 patients deemed unfit for OSR underwent EVAR or were managed conservatively. A 1:1 propensity-matched analysis incorporating age, gender, anaerobic threshold, and aneurysm size was used to compare survival. Cost-effectiveness analysis was based on the economic model for the National Institute for Health and Care Excellence clinical guideline on abdominal aortic aneurysm treatment.

RESULTS

Propensity matching produced 122 pairs of patients in the EVAR and conservative management groups. The median overall survival for the EVAR group was significantly longer than that for the conservative management group (84 vs 30 months, P < .001). One-, three-, and five-year mortality in the EVAR group was 7%, 40%, and 68%, respectively, compared with 25%, 68%, and 82% in the conservative management group, all P < .001. The increment cost-effectiveness ratio for EVAR was £8023 (US$11,644) per quality-adjusted life year gained compared with £430,602 (US$624,967) in the National Institute for Health and Care Excellence guideline, which is based on EVAR-2 results.

CONCLUSIONS

EVAR offers a survival advantage and is cost-effective in selected patients deemed unfit for OSR based on CPET compared with conservative management.

Statistical Process Control Charts for Monitoring Next-Generation Sequencing and Bioinformatics Turnaround in Precision Medicine Initiatives

Purpose

Precision oncology, such as next generation sequencing (NGS) molecular analysis and bioinformatics are used to guide targeted therapies. The laboratory turnaround time (TAT) is a key performance indicator of laboratory performance. This study aims to formally apply statistical process control (SPC) methods such as CUSUM and EWMA to a precision medicine programme to analyze the learning curves of NGS and bioinformatics processes.

Patients and Methods

Trends in NGS and bioinformatics TAT were analyzed using simple regression models with TAT as the dependent variable and chronologically-ordered case number as the independent variable. The M-estimator "robust" regression and negative binomial regression were chosen to serve as sensitivity analyses to each other. Next, two popular statistical process control (SPC) approaches which are CUSUM and EWMA were utilized and the CUSUM log-likelihood ratio (LLR) charts were also generated. All statistical analyses were done in Stata version 16.0 (StataCorp), and nominal P < 0.05 was considered to be statistically significant.

Results

A total of 365 patients underwent successful molecular profiling. Both the robust linear model and negative binomial model showed statistically significant reductions in TAT with accumulating experience. The EWMA and CUSUM charts of overall TAT largely corresponded except that the EWMA chart consistently decreased while the CUSUM analyses indicated improvement only after a nadir at the 82^nd case. CUSUM analysis found that the bioinformatics team took a lower number of cases (54 cases) to overcome the learning curve compared to the NGS team (85 cases).

Conclusion

As NGS and bioinformatics lead precision oncology into the forefront of cancer management, characterizing the TAT of NGS and bioinformatics processes improves the timeliness of data output by potentially spotlighting problems early for rectification, thereby improving care delivery.

ERA OF ENDOVASCULAR AORTIC ANEURYSM REPAIR IS LINKED TO PREOPERATIVE ANATOMIC SEVERITY AND PERIOPERATIVE PATIENT OUTCOMES

OBJECTIVE

Varying opinions on optimal elective and emergent surgical management of infrarenal AAAs are expressed by the most recent Society for Vascular Surgery (SVS), European Society for Vascular Surgery (ESVS), versus NICE (National Institutes for Health and Care Excellence, UK) guidelines. The NICE guidelines propose that open surgical repair (OSR) serve as the default treatment for infrarenal AAA. The rationale for this approach relied on data from the early era of endovascular aneurysm repair (EVAR), and are in contrast to the more balanced approaches of the SVS and ESVS. We hypothesize that significant differences in patient selection, management, and postoperative outcome are related to the era in which treatment was undertaken, contextualizing the outcomes reported in early era EVAR RCTs.

METHODS

Retrospectively, two cohorts representing all EVAR patients from "early", n= 167 (2008-2010) and "late" n=129 (2015-2017) periods at a single treating institution, were assembled. Primary outcomes of era-related changes in preoperative demographics, anatomy, and intraoperative events were assessed; anatomy was compared using the Society for Vascular Surgery Anatomic Severity Grading (ASG) system. These era-related differences were then placed in the context of early perioperative outcomes and at follow-up to one year.

RESULTS

Choice of surgical strategy differed by era, despite the same patient preoperative comorbidities between EVAR groups. Preoperative anatomic severity was significantly worse in the early cohort (p<.001), with adverse proximal and distal seal zone features (p<·001). Technical success was 16·2% higher in the late cohort, with significantly fewer type 1A/B endoleaks perioperatively (p<.001). In-hospital complications, driven by higher acute kidney injury and surgical site complications in the early cohort, resulted in a 16·5% difference between cohorts (p<0·05). At one year of follow-up, outcome differences persisted; late era patients had fewer 1A endoleaks, fewer graft complications, and better reintervention-free survival.

CONCLUSIONS

From a granular dataset of EVAR patients, we found an impact of EVAR repair era on early clinical outcome; late cohort infrarenal (IR) EVAR patients had less severe preoperative anatomy, and improved perioperative and follow-up outcomes to one year, suggesting that the results of early EVAR RCTs may no longer be generalizable to modern practice.

Supraclavicular Approach for Neurogenic Thoracic Outlet Syndrome: Description of a Learning Curve

BACKGROUND

The supraclavicular exposure represents an alternative approach for thoracic outlet decompression in neurogenic thoracic outlet syndrome with unique access to neurovascular structures. We aimed to evaluate the learning curve for this approach and associated patient outcomes.

METHODS

Patients undergoing first-time, unilateral, supraclavicular thoracic outlet decompression for neurogenic thoracic outlet syndrome were included. Cumulative-sum and linear-spline-regression analyses were used to determine the operative time learning curve. Patients were consecutively organized into early (learning phase) and late (competency) cohorts. Primary endpoints were the operative time learning curve operation number and association of this learning curve on differences in self-reported postoperative symptomatic improvement between early and late cohorts, adjusting for American Society of Anesthesiology classification, body mass index, previous treatment (opioid/neuropathic medication/botulinum-injection), and length of stay.

RESULTS

Among 114 patients, learning curve analyses showed decreasing operative times, plateauing at the 51st operation (ß = -1.63, 95% confidence interval [-2.30, -0.95], P < .001). No periprocedural differences existed between early (operations 1-50) and late (operations 51-114) cohorts. Self-reported 90-day outcomes were similar in early and late cohorts (odds ratio [OR]: 1.60 [0.65, 3.95], P = .31). Mediators of poor self-reported outcomes included increasing American Society of Anesthesiology classification (OR 0.21 [0.08, 0.54], P = .001), failed preoperative botulinum injection (OR 0.15 [0.03, 0.65], P = .01), and increased length of stay (OR 0.40 [0.22, 0.73], P = .003).

CONCLUSIONS

The learning curve for supraclavicular thoracic outlet decompression in neurogenic thoracic outlet syndrome occurred after 51 operations with a trend towards improved 90-day self-reported outcomes from the early to late phases. These findings, along with mediators of poorer outcomes, may aid surgeons in adopting a new approach and counseling patients on expected outcomes.

Learning curve of fenestrated and branched endovascular aortic repair for pararenal and thoracoabdominal aneurysms

OBJECTIVE

The objective of this study was to review the learning curve for fenestrated-branched endovascular aortic repair (F-BEVAR) of pararenal and thoracoabdominal aortic aneurysms (TAAAs).

METHODS

We reviewed the clinical data of 334 consecutive patients (255 males, mean age 75 ± 7 years) who underwent F-BEVAR between 2007 and 2016 in a single institution. Outcomes were analyzed in four quartiles of experience (Q1-Q4). Study outcomes included trends in patient characteristics, device design, procedural variables, 30-day mortality, and major adverse events (MAEs).

RESULTS

There were 178 patients (53%) treated for pararenal aneurysms and 156 (47%) for TAAAs. During the study period, there was a statistically significant increase in the proportion of TAAAs and in the number of vessels incorporated. Despite this, there was a steady decrease in 30-day mortality (6% in Q1 to 0% in Q4; P < .04) and in the rate of MAEs (60% in Q1 to 29% in Q4; P<.001). By linear regression analysis, there was significant decline in estimated blood loss (1358 ± 1517 mL in Q1 to 486 ± 520 mL in Q4; P < .001), total operating time (325 ± 116 minutes in Q1 to 248 ± 92 minutes in Q4; P < .001), total fluoroscopy time (121 ± 59 minutes in Q1 to 85 ± 39 minutes in Q4; P < .001), contrast volume (201 ± 92 mL in Q1 to 160 ± 61 mL in Q4; P = .002), and radiation dose (4141 ± 2570 mGy in Q2 to 2543 ± 1895 mGy in Q4; P < .001). Independent predictors of MAEs were total operating time (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.3-1.8; P < .001), Society for Vascular Surgery total score (OR, 1.1; 95% CI, 1.02-1.2; P = .009), and quartile 1 (OR, 3.0; 95% CI, 1.7-5.2; P < .001).

CONCLUSIONS

This study demonstrates significant improvement in perioperative mortality, MAEs, procedural variables, and secondary interventions in patients treated by F-BEVAR, despite the increase in complexity of aneurysm pathology during the study period. Also, better patient selection contributed to improve outcomes.

Cumulative sum analysis of the learning curve for the preclosure technique using Proglide

OBJECTIVES

Our study aims to assess the technical quality and the learning curve of the preclosure technique for a vascular surgeon using Proglide using cumulative sum analysis (CUSUM analysis).

METHODS

This study was designed retrospectively and enrolled 81 consecutive patients with 88 access sites who underwent endovascular aortic repair or thoracic endovascular aortic repair with the preclosure technique using Proglide between July 2017 and February 2018. The patients were divided into 2 groups chronologically: (A) the first 40 cases and (B) the latter 41 cases. Logistic regression analysis was used to assess the impact of technical risk factors on the success of the preclosure technique, and the χ2 test and 1-way ANOVA were applied to analyse the distribution of individual characteristics and risk factors between the 2 groups. CUSUM analysis was adapted to analyse the learning curve and to monitor the technical quality, with a predetermined target failure rate of 5%, an alternative failure rate of 20% and calculated 80% 'alert', 95% 'alarm' and 80% 'reassurance' lines.

RESULTS

Primary technical success was obtained in 81 (92.05%) access sites. There were no significant correlations between primary technical success and risk factors, including, common femoral artery diameter (P = 0.88), common femoral artery depth from the skin (P =0.94), the level of common femoral artery calcification (P =0.86) and size of sheath (P =0.96). Moreover, the distribution of related risk factors was not significantly different between groups A and B. CUSUM analysis showed that the cumulative failure rate never crossed the 80% 'alert' and 95% 'alarm' lines. Additionally, the failure rate began to approach the 80% 'reassurance' line after ∼22 cases and crossed the 80% 'reassurance' line after 36 cases.

CONCLUSIONS

The technique of totally percutaneous access using Proglide is safe and effective for an experienced vascular surgeon, even if the operator has no previous experience with any preclosure techniques. CUSUM analysis showed that 36 cases are necessary to achieve the target failure rate of 5%.

Using Simulation to Define the Learning Curve for the Digital Cervical Examination

INTRODUCTION

To assess how skill in the digital cervical examination is acquired in medical students.

METHODS

In a longitudinal study, medical students completed 200 simulated cervical examinations. We performed regressions of each student's cumulative accuracy using the linear, power, and sigmoidal models to determine best fit. We also constructed multilevel models to determine the influence of dilation and effacement on accuracy and to determine whether the starting level and rate of learning varied between individuals. To assess skill decay, we assessed accuracy at 1, 2, and 5 months after training. We defined the amount of sustained accuracy needed to achieve competence using cumulative summation analyses and determined the amount of practice needed to reach this level of skill.

RESULTS

Twenty-five medical students participated. The median (interquartile range) of cumulative accuracy at the end of the study was 69% (65-78) for dilation and 80% (76-91) for effacement. The sigmoidal model had the best fit. All students achieved competence during the study. The multilevel models showed that accuracy decreased with higher dilation and lower effacement and found that starting level and rate of learning varied between individuals. Maximal accuracy in both dilation and effacement was seen after 150 repetitions. Accuracy of the medical students persisted for 1 month for dilation and 2 months for effacement. The average±SD number of repetitions needed to achieve competence was 89±46 (range 35-195) for dilation and 48±38 (range 11-174) for effacement.

DISCUSSION

Based on the variability in skill between individuals and the rate of skill acquisition and decay, we feel that a competence-based rather than time-based approach is most appropriate, that trainee performance should be monitored both during and after training, and that 150 repetitions, or more, should be included in any digital cervical examination simulation regimen.

Endovascular Aneurysm Repair May Provide a Survival Advantage in Patients Deemed Physiologically Ineligible for Open Abdominal Aortic Aneurysm Repair

BACKGROUND

Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity and fitness. It can be used to guide decision making prior to major vascular surgery. The EVAR-2 trial suggested that endovascular aneurysm repair (EVAR) in patients unfit for open repair failed to provide a significant survival advantage over nonsurgical management. The aim of this study is to assess contemporary survival differences between patients with poor CPET measures who underwent EVAR or were not offered surgical intervention.

METHODS

A prospectively maintained database of CPET results of patients considered for elective infrarenal aortic aneurysm repair were interrogated. Anaerobic threshold (AT) of <11 mL/min/kg was used to indicate poor physical fitness. Hospital electronic records were then reviewed for perioperative, reintervention, and long-term outcomes.

RESULTS

Between November 2007 and October 2017, 532 aortic aneurysm repairs were undertaken, of which 376 underwent preoperative CPET. Seventy patients were identified as having an AT <11 mL/min/kg. Thirty-seven patients underwent EVAR and 33 were managed nonsurgically. All-cause survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 92%, and 81%, respectively. For those not offered surgical intervention survival at the same points was 72%, 48%, and 24% [hazard ratio, HR = 5.13 (1.67-15.82), P = 0.004]. Aneurysm-specific survival at 1, 3, and 5 years for those patients who underwent EVAR was 97%, 94%, and 94%, respectively. Survival at the same time points for those not offered surgical intervention was 90%, 69%, and 39%, respectively [HR = 7.48 (1.37-40.82), P = 0.02].

CONCLUSIONS

In this small, retrospective, single-center, nonrandomized cohort, EVAR may provide a survival advantage in patients with poor physical fitness identified via CPET. Randomized studies with current generation EVAR are required to validate the results shown here.

Trends in elective and ruptured abdominal aortic aneurysm repair by practice setting in Ontario, Canada, from 2003 to 2016: a population-based time-series analysis

BACKGROUND

Recent years have seen centralization of vascular surgery services in Ontario. We sought to examine the trends in overall and approach-specific elective and ruptured abdominal aortic aneurysm repair by hospital type (teaching v. community).

METHODS

We conducted a population-based time-series analysis of elective and ruptured abdominal aortic aneurysm repairs in Ontario, Canada, from 2003 to 2016. Quarterly cumulative incidences of repairs per 100 000 Ontarians aged 40 years and older were calculated. We fit exponential smoothing models to the data stratified by approach and hospital type to examine repair trends.

RESULTS

We identified 19 219 elective and 2722 ruptured repairs between 2003 and 2016. The cumulative incidences of overall elective repair and elective open surgical repair decreased by 1.15% (p = 0.008) and 67% (p < 0.001), respectively, in teaching hospitals and by 23% (p < 0.001) and 60% (p < 0.001), respectively, in community hospitals. The cumulative incidence of elective endovascular repair increased 667% in teaching hospitals (p < 0.001). Elective endovascular repair began in community centres after 2010 and increased to 0.98/100 000 (p < 0.001), resulting in a rebound in overall elective repair in the community. Overall ruptured repairs and ruptured open repairs decreased by 84% (p < 0.001) and 88% (p = 0.002), respectively, at community hospitals. Ruptured endovascular repairs at community hospitals increased from no procedures before 2006 to 0.03/100 000 in 2016 (p = 0.005).

INTERPRETATION

There has been substantial uptake of endovascular aortic repair in teaching and community hospitals in Ontario, and community hospital uptake of endovascular repair has begun decentralization of abdominal aortic aneurysm repair. Increased experience and training in endovascular repair and reduced specialized care requirements will probably lead to continued decentralization.

Lessons learned and learning curve of fenestrated and branched endografts

Fenestrated and branched endovascular repair (F-BEVAR) has been increasingly used to treat patients with complex aortic aneurysms involving the renal-mesenteric arteries. As with any new procedure, there is a learning curve associated with mastering the technique. However, proficiency with deployment is only one aspect of the learning process, and ultimately, this curve is defined not by one quality parameter, but by patient selection, the performance of the entire team, the surgeon's ability to adapt to unexpected events, and the durability of the repair. This article reviews the importance of novel training paradigms, learning curve, and factors affecting outcomes of complex endovascular aneurysm repair.

A methodology for in silico endovascular repair of abdominal aortic aneurysms

Endovascular aneurysm repair (EVAR) can involve some unfavorable complications such as endoleaks or stent-graft (SG) migration. Such complications, resulting from the complex mechanical interaction of vascular tissue, SG and blood flow or incompatibility of SG design and vessel geometry, are difficult to predict. Computational vascular mechanics models can be a predictive tool for the selection, sizing and placement process of SGs depending on the patient-specific vessel geometry and hence reduce the risk of potential complications after EVAR. In this contribution, we present a new in silico EVAR methodology to predict the final state of the deployed SG after intervention and evaluate the mechanical state of vessel and SG, such as contact forces and wall stresses. A novel method to account for residual strains and stresses in SGs, resulting from the precompression of stents during the assembly process of SGs, is presented. We suggest a parameter continuation approach to model various different sizes of SGs within one in silico EVAR simulation which can be a valuable tool when investigating the issue of SG oversizing. The applicability and robustness of the proposed methods are demonstrated on the example of a synthetic abdominal aortic aneurysm geometry.

Validation of the VBLaST pattern cutting task: a learning curve study

BACKGROUND

Mastery of laparoscopic skills is essential in surgical practice and requires considerable time and effort to achieve. The Virtual Basic Laparoscopic Skill Trainer (VBLaST-PC^©) is a virtual simulator that was developed as a computerized version of the pattern cutting (PC) task in the Fundamentals of Laparoscopic Surgery (FLS) system. To establish convergent validity for the VBLaST-PC^©, we assessed trainees' learning curves using the cumulative summation (CUSUM) method and compared them with those on the FLS.

METHODS

Twenty-four medical students were randomly assigned to an FLS training group, a VBLaST training group, or a control group. Fifteen training sessions, 30 min in duration per session per day, were conducted over 3 weeks. All subjects completed pretest, posttest, and retention test (2 weeks after posttest) on both the FLS and VBLaST^© simulators. Performance data, including time, error, FLS score, learning rate, learning plateau, and CUSUM score, were analyzed.

RESULTS

The learning curve for all trained subjects demonstrated increasing performance and a performance plateau. CUSUM analyses showed that five of the seven subjects reached the intermediate proficiency level but none reached the expert proficiency level after 150 practice trials. Performance was significantly improved after simulation training, but only in the assigned simulator. No significant decay of skills after 2 weeks of disuse was observed. Control subjects did not show any learning on the FLS simulator, but improved continually in the VBLaST simulator.

CONCLUSIONS

Although VBLaST^©- and FLS-trained subjects demonstrated similar learning rates and plateaus, the majority of subjects required more than 150 trials to achieve proficiency. Trained subjects demonstrated improved performance in only the assigned simulator, indicating specificity of training. The virtual simulator may provide better opportunities for learning, especially with limited training exposure.

A simulator for training in endovascular aneurysm repair: The use of three dimensional printers

OBJECTIVES

To develop an endovascular aneurysm repair (EVAR) simulation system using three dimensional (3D) printed aneurysms, and to evaluate the impact of patient specific training prior to EVAR on the surgical performance of vascular surgery residents in a university hospital in Brazil.

METHODS

This was a prospective, controlled, single centre study. During 2015, the aneurysms of patients undergoing elective EVAR at São Paulo University Medical School were 3D printed and used in training sessions with vascular surgery residents. The 3D printers Stratasys-Connex 350, Formlabs-Form1+, and Makerbot were tested. Ten residents were enrolled in the control group (five residents and 30 patients in 2014) or the training group (five residents and 25 patients in 2015). The control group performed the surgery under the supervision of a senior vascular surgeon (routine procedure, without simulator training). The training group practised the surgery in a patient specific simulator prior to the routine procedure. Objective parameters were analysed, and a subjective questionnaire addressing training utility and realism was answered.

RESULTS

Patient specific training reduced fluoroscopy time by 30% (mean 48 min, 95% confidence interval [CI] 40-58 vs. 33 min, 95% CI 26-42 [p < .01]), total procedure time by 29% (mean 292 min [95% CI 235-336] vs. 207 [95% CI 173-247]; p < .01), and volume of contrast used by 25% (mean 87 mL [95% CI 73-103] vs. 65 mL [95% CI 52-81]; p = .02). The residents considered the training useful and realistic, and reported that it increased their self confidence. The 3D printers Form1+ (using flexible resin) and Makerbot (using silicone) provided the best performance based on simulator quality and cost.

CONCLUSION

An EVAR simulation system using 3D printed aneurysms was feasible. The best results were obtained with the 3D printers Form1+ (using flexible resin) and Makerbot (using silicone). Patient specific training prior to EVAR at a university hospital in Brazil improved residents' surgical performance (based on fluoroscopy time, surgery time, and volume of contrast used) and increased their self confidence.

The Role of Learning in Health Technology Assessments: An Empirical Assessment of Endovascular Aneurysm Repairs in German Hospitals

Changes in performance due to learning may dynamically influence the results of a technology evaluation through the change in effectiveness and costs. In this study, we estimate the effect of learning using the example of two minimally invasive treatments of abdominal aortic aneurysms: endovascular aneurysm repair (EVAR) and fenestrated EVAR (fEVAR). The analysis is based on the administrative data of over 40,000 patients admitted with unruptured abdominal aortic aneurysm to more than 500 different hospitals over the years 2006 to 2013. We examine two patient outcomes, namely, in-hospital mortality and length of stay using hierarchical regression models with random effects at the hospital level. The estimated models control for patient and hospital characteristics and take learning interdependency between EVAR and fEVAR into account. In case of EVAR, we observe a significant decrease both in the in-hospital mortality and length of stay with experience accumulated at the hospital level; however, the learning curve for fEVAR in both outcomes is effectively flat. To foster the consideration of learning in health technology assessments of medical devices, a general framework for estimating learning effects is derived from the analysis. © 2017 The Authors. Health Economics published by John Wiley & Sons, Ltd.

Midterm Results of Endovascular Infrarenal Abdominal Aortic Aneurysm Repair in High-Risk Patients

Short-term and midterm clinical outcomes after endovascular repair of abdominal aortic aneurysms (AAAs) have been well documented. Evaluation of longer term outcomes is now possible. Here we describe our initial 100 high-risk patients treated with endovascular aneurysm repair (EVAR), all with a minimum of 5 years of follow-up. A retrospective review of prospectively recorded data in a departmental database was undertaken for the first 100 consecutive EVAR patients with a minimum of 5 years (range, 60-105 months) of follow-up performed between December 1997 and June 2001. Information was obtained from surgical follow-up visits and family doctors' offices. Endovascular repair of AAA in high-risk patients can be achieved with acceptably low postoperative mortality and morbidity. Longer term results in this high-risk cohort suggest that EVAR is effective in preventing aneurysm-related deaths at 5 years and beyond. All late mortalities were due to patients' comorbid diseases.

The Association Between a Surgeon’s Learning Curve With Endovascular Aortic Aneurysm Repair and Previous Institutional Experience

The purpose of the present study was to determine whether an institution’s prior endovascular experience influenced the learning curve of subsequent surgeons. A prospective analysis of the initial 70 endovascular abdominal aortic aneurysm repair (EVAR) cases attempted by an individual surgeon was performed with the primary outcome variable being achievement and 30-day maintenance of initial clinical success. Along with standard statistical analyses, the cumulative sum failure method (CUSUM) was used to analyze the learning curve, with a predetermined acceptable failure rate of 10%. Seventy elective EVAR cases were performed by this surgeon during a 4-year period (2000-2004) (mean age, 73.7 ∓ 5.4 years; mean aneurysm diameter 63.3 ∓ 7.2 mm). Initial clinical success was achieved in 68 of 70 cases (97%), which differed significantly with that of our initial surgeon (88.5%, P = .01). Causes of failure in the present series included 1 early mortality (1.4%) and 1 case of conversion to open repair with no instances of type I endoleak or endograft limb thrombosis. Both surgeons’ cases were plotted sequentially with CUSUM curves revealing a significantly shorter learning curve for the second surgeon. Optimal results were achieved following 10 to 20 EVAR cases, as opposed to 60 cases in the initial series. Such an analysis confirms that as an institution’s experience with EVAR increases, an individual surgeon’s learning curve shortens considerably.

Amsterdam Acute Aneurysm Trial: Background, Design, and Methods

The objective of the Amsterdam Acute Aneurysm Trial is to study the combined outcome of conventional emergency surgery versus endovascular treatment for ruptured abdominal aortic aneurysms. The design used was a multicenter randomized clinical trial conducted in two university hospitals and one teaching hospital in the Amsterdam region. The study included all patients with a ruptured abdominal aneurysm who were eligible for endovascular and conventional surgery. The primary end points were combined mortality and severe morbidity. The secondary end points were quality of life and cost-effectiveness. The background, design, and methods of this trial are presented, and the ethical and legal issues of this type of research are discussed.

Comparison of Learning Curves for Major and Minor Laparoscopic Liver Resection

BACKGROUND

Because laparoscopic liver resection (LLR) has a steep learning curve, analyzing experience is important for trainees. Several authors have described the learning curve of LLR, without comparing the learning curves between major and minor LLR.

METHODS

Perioperative data were retrieved from the medical records of 170 consecutive patients who underwent LLR by a single surgeon at a tertiary hospital. Learning curves were generated and compared between major and minor LLR using cumulative sum control charts and the moving average.

RESULTS

Major and minor LLR was performed in 96 and 74 patients, respectively. The learning curves showed a steady state after case 50 for major LLR. Because of discordant results in minor LLR, subgroup analyses were performed, showing competency in LLR after cases 25 and 35 for left lateral sectionectomy and tumorectomy, respectively. Transfused red blood cell volume (0.6 versus 2.2 packs, P < .001) decreased after achievement of competence in major LLR. Blood loss exceeding 500 mL (odds ratio 2.395, 95% confidence interval 1.096-5.233, P = .028) was independently associated with LLR failure.

CONCLUSIONS

The number of cases required to accomplish LLR differed according to the extent of resection. Extensive blood loss was independently associated with LLR failure.

Cumulative summation analysis of learning curve for robot-assisted gastrectomy in gastric cancer

BACKGROUND

The purpose of this study was to determine the learning curve for robot-assisted gastrectomy using the Cumulative Summation (CUSUM) technique.

METHODS

Two series of consecutive robotic gastrectomy were retrospective analyzed. Patient demographics, surgical performance, and short-term outcomes were examined and data of operation time were abstracted for the learning curve analysis.

RESULTS

Similar processes occurred in the two surgeons. Each of their learning curves of robotic gastrectomy was best modeled as a third-order polynomial, with equation CUSUMOT in minutes equal to 0.0495 case number (3) - 4.217 case number(2) + 91.206 case number 100.11(R(2) =  .8731) for surgeon A and 0.0314 case number (3) - 2.4106 case number(2) + 33.682 case number + 315.28(R(2) = 0.8816) for surgeon B. They both included three unique phases: an initial phase, a well-developed phase, and a mastery phase after the accumulation of additional experience.

CONCLUSION

The CUSUM method is a useful tool for objective evaluation of practical skills for surgeons during the learning phase of robotic surgery training. The robotic gastrectomy is found to have a short learning curve for experienced laparoscopic surgeons and the popularity of this new technology won't reduce because of its difficulty to learn.

Long-term cost-effectiveness analysis of endovascular versus open repair for abdominal aortic aneurysm based on four randomized clinical trials

Background

A number of published economic evaluations of elective endovascular aneurysm repair (EVAR) versus open repair for abdominal aortic aneurysm (AAA) have come to differing conclusions about whether EVAR is cost-effective. This paper reviews the current evidence base and presents up-to-date cost-effectiveness analyses in the light of results of four randomized clinical trials: EVAR-1, DREAM, OVER and ACE.

Methods

Markov models were used to estimate lifetime costs from a UK perspective and quality-adjusted life-years (QALYs) based on the results of each of the four trials. The outcomes included in the model were: procedure costs, surveillance costs, reintervention costs, health-related quality of life, aneurysm-related mortality and other-cause mortality. Alternative scenarios about complications, reinterventions and deaths beyond the trial were explored.

Results

Models based on the results of the EVAR-1, DREAM or ACE trials did not find EVAR to be cost-effective at thresholds used in the UK (up to £30 000 per QALY). EVAR seemed cost-effective according to models based on the OVER trial. These results seemed robust to alternative model scenarios about events beyond the trial intervals.

Conclusion

These analyses did not find that EVAR is cost-effective compared with open repair in the long term in trials conducted in European centres. EVAR did appear to be cost-effective based on the OVER trial, conducted in the USA. Caution must be exercised when transferring the results of economic evaluations from one country to another.

Looking for a Learning Curve in EVAR Based on the Zenith Stent Graft

The purpose of this study was to report the learning curve of endovascular aneurysm repair (EVAR) based on the Zenith stent graft (Cook Medical Inc., Bloomington, IN). In the last 9 years, 101 patients were treated with a Zenith stent graft. To display the learning curve, a cumulative sum (CUSUM) failure analysis curve of the 30-day technical success rate was calculated. For detailed analysis, our EVAR patient cohort was chronologically divided into three groups. Technical and clinical results, basic patient parameters, and procedural data were compared. The CUSUM graph indicated an initial sharp rise within the first 35 cases and a plateau thereafter. The 30-day technical success rate significantly increased from the first to the second group (83 vs. 100%; p = 0.019), as did the primary technical success rate (66 vs. 97%; p = 0.001). EVAR based on the Zenith stent graft required ∼35 cases to reach a stably high rate of short-term technical success.

Late reduction in congenital dislocation of the hip and the need for secondary surgery: radiologic predictors and confounding variables

BACKGROUND

Despite early recognition and appropriate treatment of congenital dislocation of the hip, there are a number of cases that subsequently require further surgery to prevent progressive dysplasia, instability, and eventual early osteoarthritis. This study aimed (1) to determine the incidence of pelvic osteotomy (PO) after late open (OR) or closed (CR) reduction for failed initial conservative treatment or late presentation; (2) study potential radiologic predictors of those that will require a secondary procedure; (3) and to evaluate the effect of potential confounding variables including age of reduction, Pavlik harness treatment, and surgical experience on PO rate.

METHODS

All cases of congenital dislocation of the hip that presented late or had failed conservative treatment with subsequent late OR versus CR, that were carried out during 1988 to 2003, by the lead surgeon were included. Dislocations secondary to neuromuscular causes or teratologic causes were excluded. Intraoperative arthrograms confirmed the concentric or eccentric reduction and determined subsequent intervention. The AP pelvis plain radiograph was used to measure the height of dislocation, as described by Tonnis, and monitor Acetabular index, and ossific nucleus width and height postreduction.

RESULTS

After 134 OR's, 24 hips (19%, 95% CI: 16-23%) later required a pelvic osteotomy compared with 59 out of 104 hips (58%, 95% CI: 49-68%) in the CR cohort. There was no statistical difference in avascular necrosis rates between late OR (10.9%, 95% CI: 4.8-17%) and CR (11.4%, 95% CI: 5.8-17%). Acetabular index was a reliable predictor for the need of subsequent PO becoming significantly different in those that did (PO group) and did not (non-PO group) require further surgery approximately 1.5 years postreduction. There was no difference in the ON development after reduction in both PO and non-PO groups. The PO requirement was not affected by earlier failed Pavlik harness treatment but did change with ongoing surgical experience. Late OR produced the lowest secondary procedure rate without an increase in the incidence of avascular necrosis. There is a learning curve to this procedure that will affect these outcomes.

LEVEL OF EVIDENCE

Level III (Case-control study).

Resident learning curve for minimal-access transforaminal lumbar interbody fusion in a military training program

Object

Minimal-access transforaminal lumbar interbody fusion (TLIF) has gained popularity as a method of achieving interbody fusion via a posterior-only approach with the aim of minimizing injury to adjacent tissue. While many studies have reported successful outcomes, questions remain regarding the potential learning curve for successfully completing this procedure. The goal of this study, based on a single resident's experience at the only Accreditation Council for Graduate Medical Education–approved neurosurgical training center in the US military, was to determine if there is in fact a significant learning curve in performing a minimal-access TLIF.

Methods

The authors retrospectively reviewed all minimal-access TLIFs performed by a single neurosurgical resident between July 2006 and January 2008. Minimal-access TLIFs were performed using a tubular retractor inserted via a muscle-dilating exposure to limit approach-related morbidity. The accuracy of screw placement and operative times were assessed.

Results

A single resident/attending team performed 28 minimal-access TLIF procedures. In total, 65 screws were placed at L-2 (1 screw), L-3 (2 screws), L-4 (18 screws), L-5 (27 screws), and S-1 (17 screws) from the resident's perspective. Postoperative CTs were reviewed to determine the accuracy of screw placement. An accuracy of 95.4% (62 of 65) properly placed screws was noted on postoperative imaging. Two screws (at L-5 in the patient in Case 17 and at S-1 in the patient in Case 9) were lateral, and no revision was needed. One screw (at L-4 in Case 24) was 1 mm medial without symptoms or the need for revision. In evaluating the operative times, 2 deformity cases (Grade III spondylolisthesis) were excluded. The average operating time per level in the remaining 26 cases was 113.25 minutes. The average time per level for the first 13 cases was 121.2 minutes; the amount of time decreased to 105.3 minutes for the second group of 13 cases (p = 0.25).

Conclusions

In summary, minimal-access TLIF can be safely performed in a training environment without a significant complication rate due to the expected learning curve.

Propensity scored analysis of outcomes after ruptured abdominal aortic aneurysm

Background

This study examined the population outcome of ruptured abdominal aortic aneurysm (rAAA) in England, the role of endovascular repair (EVAR), and the relationship between outcome and hospital workload.

Methods

Data were retrieved from Hospital Episode Statistics between 1 April 2003 and 31 March 2008. Propensity scoring was used to compare the outcomes of stratified patients undergoing EVAR and open repair. The relationship between workload and outcome was determined.

Results

Some 3725 urgent and 4414 rAAA repairs were included. Mortality rates were 21·3 per cent for urgent repair and 46·3 per cent for rAAA repair. EVAR was employed for 16·3 and 7·6 per cent of urgent and rAAA repairs respectively. EVAR was associated with significantly reduced mortality for urgent repair (odds ratio (OR) 0·531, 95 per cent confidence interval 0·415 to 0·680; P &lt; 0·001) and rAAA repair (OR 0·527, 0·416 to 0·668; P &lt; 0·001). A propensity scored analysis confirmed the benefit of EVAR for rAAA repair (P &lt; 0·001). Repair of rAAA at hospitals with a higher elective aneurysm workload was associated with lower mortality rates irrespective of the mode of treatment (P &lt; 0·001). Higher-volume hospitals were more likely to operate on rAAA (P = 0·033).

Conclusion

EVAR offered a survival advantage over open repair for non-elective aneurysm procedures. Services for the treatment of rAAA should incorporate access to EVAR and would benefit from being based in units with a high elective caseload.

Effects of study design and trends for EVAR versus OSR

Purpose:

To investigate if study design factors such as randomization, multi-center versus single center evidence, institutional surgical volume, and patient selection affect the outcomes for endovascular repair (EVAR) versus open surgical repair (OSR). Finally, we investigate trends over time in EVAR versus OSR outcomes.

Methods:

Search strategies for comparative studies were performed individually for: OVID’s MEDLINE, EMBASE, CINAHL, HAPI, and Evidence Based Medicine (EBM) Reviews (including Cochrane DSR, ACP Journal Club, DARE and CCTR), limited to 1990 and November 2006.

Results:

Identified literature: 84 comparative studies pertaining to 57,645 patients. These include 4 randomized controlled trials (RCTs), plus 2 RCTs with long-term follow-up. The other 78 comparative studies were nonrandomized with 75 reporting perioperative outcomes, of which 16 were multi-center, and 59 single-center studies. Of the single-center studies 31 were low-volume and 28 were high-volume centers. In addition, 5 studies had all patients anatomically eligible for EVAR, and 8 studies included high-risk patients only. Finally, 25 long term observational studies reported outcomes up to 3 years.

Outcomes:

Lower perioperative mortality and rates of complications for EVAR versus OSR varied across study designs and patient populations. EVAR adverse outcomes have decreased in recent times.

Conclusion:

EVAR highlights the problem of performing meta-analysis when the experience evolves over time.

National outcomes for the treatment of ruptured abdominal aortic aneurysm: comparison of open versus endovascular repairs

OBJECTIVES

Endovascular repair (EVAR) of ruptured abdominal aortic aneurysms (rAAA) has been shown to acutely decrease procedural mortality compared to open aortic repair (OAR). However, little is known about the effect of choice of procedure; EVAR vs OAR, or the impact of physician and institution volume on long-term survival and outcome.

METHODS

Patients hospitalized with rAAA who underwent either OAR or EVAR, were derived from the Medicare inpatient dataset (1995-2004) using ICD9 codes. We evaluated long-term survival after OAR and EVAR in the entire fee-for-service Medicare population, and then in patients matched by propensity score to create two similar cohorts for comparison with Kaplan-Meier analysis. Annual surgeon and hospital volumes of EVAR (elective and ruptured), OAR (elective and ruptured), and rAAA (EVAR and OAR) were divided into quintiles to determine if increasing volumes correlate with decreasing mortality. Predictors of survival were determined by Cox modeling.

RESULTS

A total of 43,033 Medicare beneficiaries had rAAA repair: 41,969 had OAR and 1,064 had EVAR. The proportions of patients with diabetes, hypertension, cardiovascular, cerebrovascular, renal disease, hyperlipidemia, and cancer were statistically higher in the EVAR than in the OAR group, whereas lower extremity vascular disease was higher in the OAR group. The initial evaluation of EVAR vs OAR, prior to propensity matching, showed no statistical advantage in EVAR-survival after 90 days. The survival analysis of patients matched by propensity score showed a benefit of EVAR over OAR that persisted throughout the 4 years of follow-up (P = .0042). Perioperative and long-term survival after rAAA repair correlated with increasing annual surgeon and hospital volume in OAR and EVAR and also with rAAA experience. EVAR repair had a protective effect (HR = 0.857, P = .0061) on long-term survival controlling for comorbidities, demographics, and hospital and surgeon volume.

CONCLUSION

When EVAR and OAR patients are compared using a reliable statistical technique such as propensity analysis, the perioperative survival advantage of rAAA repaired endovascularly is maintained over the long term. Institutional experience with rAAA is critical for survival after either OAR or EVAR.

Impact of the introduction of endovascular aneurysm repair in high-risk patients on our practice of elective treatment of infrarenal abdominal aortic aneurysms

The aim of this work was to evaluate, in terms of activity and immediate postoperative results, the modifications of our elective surgical treatment of infrarenal abdominal aortic aneurysms (AAAs) resulting from the use of stent grafts to treat AAAs, following the recommendations issued by the French Health Products Safety Agency (AFSSAPS) in December 2003. This monocentric and retrospective study used the clinical data of patients operated on for asymptomatic AAA between January 2001 and December 2006. Endovascular treatment of AAAs with aortic stent grafts was introduced in our current practice in January 2004, following the recommendations of the AFSSAPS (high-risk patients for open surgery presenting with an AAA > or =50 mm). Group I was composed of patients operated on between January 2001 and December 2003 according to the standard open technique. Group II was composed of patients operated on between January 2004 and December 2006 with either standard open surgery or endovascular surgery. The main criteria of evaluation were the number of operated patients, their American Society of Anesthesiology (ASA) score of surgical risk, and the intrahospital morbidity and mortality. The number of treated patients significantly increased between these two periods (group I n = 49, group II n = 88, with 38 endovascular treatments; p < 0.001), without any changes in average age (70 vs. 72 years), percentage of men (93.7% vs. 95.5%), and mean AAA size (57.8 vs. 56 mm) between the two groups. ASA scores were significantly higher in group II (ASA III and IV, group I = 20.4% vs. group II = 55.7%; p < 0.0001), whereas the intrahospital mortality rate (4.1% vs. 3.4%) and the rate of major postoperative complications (16.3% vs. 11%) have remained stable. In group II, the median duration of hospitalization was significantly reduced (12 vs. 9 days, p < 0.001). In conclusion, in our center, following the AFSSAPS recommendations, the introduction of endovascular treatment has enabled us to electively treat a greater number of AAA patients with higher surgical risk, without aggravating the immediate postoperative results.

Learning curves for laparoscopic sigmoidectomy used to manage curable sigmoid colon cancer: single-institute, three-surgeon experience

BACKGROUND

Laparoscopic surgery demands mastery of a steep learning curve. Defining a learning curve in laparoscopic surgery is useful for planning training programs or clinical trials. This study aimed to define the learning curves for laparoscopic sigmoidectomy used to manage curable sigmoid colon cancer by evaluating early surgical outcome data from three colorectal surgeons.

METHODS

This study analyzed data from 138 consecutive patients undergoing laparoscopic sigmoidectomy for curable sigmoid colon cancer performed by three colorectal surgeons between May 2001 and November 2006. The learning curve for each surgeon were generated using the moving average method to assess changes in operation time and cumulative sum (CUSUM) analysis to assess changes in failure rates [(failure = conversion to open surgery, major perioperative complication, or failure to harvest an adequate number of lymph nodes (<12 nodes)].

RESULTS

Learning curves generated with the moving average method indicated that the operation time reached a steady state after 42 cases for surgeon A, 35 cases for surgeon B, and 30 cases for surgeon C. The overall open conversion rate was 2.9%. There was only one laparoscopy-related perioperative major complication (0.7%). An inadequate number of lymph nodes was harvested in 10 cases (7.2%): 6 (10.5%) for surgeon A, 1 (2.4%) for surgeon B, and 3 (7.7%) for surgeon C. Learning curves generated using CUSUM analysis based on a 90% success rate showed that adequate learning occurred after 10 cases for surgeon A, 17 cases for surgeon B, and 5 cases for surgeon C.

CONCLUSION

Pertinent learning curves for laparoscopic sigmoidectomy used to manage curable sigmoid colon cancer can be generated using the moving average method and CUSUM analysis. These results are likely to be useful in designing laparoscopic training programs and clinical trials aimed at investigating outcomes of laparoscopic colorectal cancer surgery.

Learning curve analysis of thoracic endovascular aortic repair in relation to credentialing guidelines

OBJECTIVE

Recently, practice guideline documents have recommended the completion of different levels of interventional experience and 5 or 10 thoracic endovascular aortic cases prior to surgeon credentialing. This study's purpose was to determine whether these requirements are valid by reviewing three surgeons' learning curves with thoracic aortic endovascular repairs.

METHODS

Between 1998 and 2006, 67 patients underwent emergent or elective endovascular repair of thoracic aortic pathologies by one of three vascular surgeons with extensive experience with catheter manipulation and abdominal aortic endografts. Following standard retrospective review, each surgeon's learning curve was analyzed using the cumulative sum failure method with a target success rate of 95% derived from the literature. The main outcome variable was primary technical success.

RESULTS

These 67 patients presented with several pathologies including elective (n = 31) and ruptured (n = 11) thoracic aortic aneurysms, acute dissections or aortic ulcers (n = 10), and acute blunt thoracic aortic trauma (n = 15). The mean age was 65 (range: 20 to 90) and the early (30 day) mortality rate was 19.4% in urgent cases (n = 36) and 0% in elective cases (n = 31). Paraplegia occurred in two patients (3%). Primary technical success was achieved in 62 cases (92.5%) and did not differ between surgeons (92.6%, 91.3%, 94.1%, respectively; P = .9). Each surgeon's cases were plotted sequentially and the resulting learning curves were similar. Although acceptable outcomes were obtained throughout the study period, improved results, compared with the target success rate, were not achieved until each surgeon treated 5 to 10 patients.

CONCLUSION

This study supports the case volume requirements of the Society for Vascular Surgery credentialing guidelines, which also requires extensive catheter and guidewire experience. With this background in catheter manipulation and endovascular abdominal aortic repair, surgeons can achieve optimal outcomes with thoracic aortic lesions following 5 to 10 cases.

Comparison of learning curves and skill transfer between classical and robotic laparoscopy according to the viewing conditions: implications for training

BACKGROUND

The purpose of this study was to evaluate the perceptual (2-dimensional [2D] vs. 3-dimensional [3D] view) and instrumental (classical vs. robotic) impacts of new robotic system on learning curves.

METHODS

Forty medical students without any surgical experience were randomized into 4 groups (classical laparoscopy with 3D-direct view or with 2D-indirect view, robotic system in 3D or in 2D) and repeated a laparoscopic task 6 times. After these 6 repetitions, they performed 2 trials with the same technique but in the other viewing condition (perceptive switch). Finally, subjects performed the last 3 trials with the technique they never used (technical switch). Subjects evaluated their performance answering a questionnaire (impressions of mastery, familiarity, satisfaction, self-confidence, and difficulty).

RESULTS

Our study showed better performance and improvement in 3D view than in 2D view whatever the instrumental aspect. Participants reported less mastery, familiarity, and self-confidence and more difficulty in classical laparoscopy with 2D-indirect view than in the other conditions.

CONCLUSIONS

Robotic surgery improves surgical performance and learning, particularly by 3D view advantage. However, perceptive and technical switches emphasize the need to adapt and pursue training also with traditional technology to prevent risks in conversion procedure.

Quality control of surgical and interventional procedures: a review of the CUSUM

BACKGROUND

The report of the CUSUM across surgical and interventional procedures has spawned a fair confusion in the literature.

AIM

To assess the use of the CUSUM and to clarify its utilisation in the perspective of future studies. Nature of the study: Retrospective review.

METHODS

A systematic literature search of Medline was carried out. From each article, data regarding the design of the study, the specialty, the performance criterion, the unit under control, the methodology and the model of the CUSUM used, the use of a graph, the use of a test and the type of test applied were retrieved.

RESULTS

31 studies were found relevant. The design was mainly retrospective for the analysis of the learning curve. The main performance criteria under control were morbidity, mortality and success of the procedure. A graph was plotted in all studies as a CUSUM plot or as cumulative sums of non-negative values. A test was used in 17 studies. Mislabelling of the plot and the test, and misuse of control limits were the most commonly reported mistakes.

CONCLUSION

The CUSUM tool is not yet properly reported in the surgical literature. Therefore, reporting of the CUSUM should be clarified and standardised before its use widens.

Learning curves in orthopaedic surgery: a case for super-specialisation?

INTRODUCTION

The objective of this study was to assess if there is a significant learning curve in the treatment of developmental dysplasia of the hip.

PATIENTS AND METHODS

We followed up cases of developmental dysplasia of the hip treated by a single surgeon over a 12-year period. There were 96 cases, 56 treated by open reduction and 40 treated by closed reduction. Assessment was made of the incidence and degree of avascular necrosis in the treated hips, as a radiological outcome measure.

RESULTS

Plotting the cumulative percentage of satisfactory outcomes demonstrated an increasingly high percentage of satisfactory results with increasing number of procedures performed, i.e. as the surgeon progressed up the 'learning curve'.

CONCLUSIONS

This study demonstrates a learning curve in the treatment of developmental dysplasia of the hip. It may be possible to draw parallels to other treatments, and also support for the growing trend to specialisation.

Cumulative sum procedure in evaluation of EUS-guided FNA cytology: the learning curve and diagnostic performance beyond sensitivity and specificity

BACKGROUND

Using cumulative sum (CUSUM) chart, we address two questions: (i) Over time, how will an EUS-FNA (endoscopic ultrasound guided fine needle aspiration) service maintain an acceptable non-diagnostic rate defined as technical failures, unsatisfactory specimens and atypical and suspicious diagnoses? (ii) Over time, how will EUS-FNA maintain acceptable diagnostic errors (false-positives plus false-negative diagnosis)?

METHODS

The study included all consecutive patients who underwent EUS-FNA at our institution from July 2000 to October 2003 and were followed up until December 2004. Using a simple spread sheet, we designed CUSUM charts and used them to track trends and assess performance at a preset acceptable rate of 10% and a preset unacceptable rate of 15% for non-diagnostic rate and diagnostic errors. We assessed all cases collectively and then in groups defined by site, size and cytopathologist.

RESULTS

Of 876 patients undergoing EUS-FNA, 83 (9.5%) had non-diagnostic results: 43 (51%) of these diagnoses were 'atypical', 27(33%) were 'suspicious for malignancy', eight (10%) were 'insufficient material for diagnosis' and five (6%) were 'technical failure'. In 585 cases with adequate follow up, there were 26 (6.3%) diagnostic errors: three (0.5%) were false positive and 23 (3.1) were false negative. The overall CUSUM charts for both non-diagnostic rate and for diagnostic error rate start with a small period of learning then cross to a significantly acceptable level at case numbers 121 and 97 respectively. Our diagnostic performance was better in lymph nodes than in the pancreas and other organs and was not significantly different for lesions <or=25 mm compared with lesion >25 mm in diameter. Performance was better for pathologists with prior experience than for pathologists without experience.

CONCLUSION

In the current climate of proficiency testing, error tracking and competence evaluation, there is a great potential for the use of CUSUM charts to assess procedure failure and error tracking in quality control programs, particularly when a new procedure such as EUS-FNA is introduced in the laboratory. Additionally, the method can be used to assess trainee competency and to track the proficiency of practicing cytologists.