CUSUM Curve Research Articles

Clinical audit of endoscopic sub-mucosal dissection performed for complex lateral spreading colorectal tumors from a region non-endemic for colorectal cancer.

Endoscopic resection is currently the treatment of choice for laterally spreading tumors (LSTs). Endoscopic sub-mucosal dissection (ESD) can achieve higher enbloc resection and R0 resection, albeit at a slightly higher risk of complications. Given scarce data on ESD from India, we performed a retrospective analysis of our experience with colorectal ESD (CR-ESD) to know its clinical efficacy and complications as well as to assess the learning curve of CR-ESD in non-endemic-areas. Retrospective analysis of prospectively maintained datasheet performed. All patients with large (>2cm), complex or recurrent colorectal LST who underwent ESD at our center between 2012 and 2021 were included in the study. Various baseline lesion-related parameters, procedure-related parameters, enbloc resection (ER) rates, R0 margins and adverse event rates were retrieved. CUSUM analysis was performed to calculate the minimum required procedures to achieve competency in CR-ESD. Total 149 patients were included in the study; mean patient age was 61.36±18.21 years. Most patients had lesions in rectum (n=102; 68.5%) followed by sigmoid colon (n=25; 16.8%). The mean lesion size was 46.62 ± 25.46 mm and the mean procedure duration for ESD was 219.30 ± 150.05 min. ER was achieved in 94.6% of lesions. R0 resection was achieved in 132 patients (88.6%). Overall, six (4%) adverse events were noted, of which one required surgical intervention.As many as 105patients (70.5%) had adenomatous lesions on histology. Seventy-four patients underwent follow-up colonoscopy, of which three had a recurrence of adenomatous lesions and five had post-resection stricture requiring endoscopic dilation. CUSUM curve analysis calculated the learning curve for ESD was 47 resections for ER and 55 for the occurrence of AEs, with a composite CUSUM at 47 procedures. CR-ESD even in non-endemic area is associated with high enbloc resection rates, R0 resection rates and acceptable complication profile. Approximately 50 cases of CR-ESD are required to achieve competency.

Cumulative sum analysis of the learning curve for retrograde intrarenal stone surgery in newbie surgeons.

This study investigated the learning curve of retrograde intrarenal surgery (RIRS) in patients with medium-sized stones using cumulative sum analysis (CUSUM) to evaluate the competence and proficiency of three new surgeons during their first RIRS procedures. We conducted a retrospective review of 227 patients from 2019 to 2022 at a single institution. The patients were divided into four groups based on the operating surgeon: tutor surgeon (85 patients), newbie surgeon A (21 patients), newbie surgeon B (85 patients), and newbie surgeon C (36 patients). Patients had one or multiple stones with the largest stone diameter fell within the range of 10-30mm. Fragmentation efficacy was calculated as "removed stone volume (mm3) divided by operative time (minutes)." CUSUM analysis monitored changes in fragmentation efficacy and validated surgical outcomes. No statistically significant differences were observed in the total stone volume, maximum stone size, or total operation time between the three newbie surgeons and the tutor surgeon. The mean fragmentation efficacy value was comparable among the newbie surgeons, but significantly different from that of the tutor surgeon. The minimum acceptable fragmentation efficacy level was set at 25.12mL/min, based on the tutor's average value. The CUSUM curves for the three surgeons initially remained relatively flat until Cases 12-15, after which they increased and eventually plateaued. Stone-free rates and postoperative complications did not differ significantly among the surgeons. Learning curve analysis for the three newbie surgeons indicated that approximately 12-15 cases were required to reach a plateau.

Laparoscopic radical gastrectomy for gastric cancer: Long-term outcome in a teaching center

BackgroundLaparoscopic gastrectomy for gastric cancer (GC) are increasing, yet the evidence of the relationship between the learning curve and long-term outcomes is limited. AimsTo analyze the relationship between the learning curve and survival in GC patients over a 10-year period. MethodsThis retrospective cohort study studied 3674 patients who underwent laparoscopic radical gastrectomy for gastric cancer. Cusum and Cox regression analysis were used to assess the association between the surgeon's experience and the 3 years overall survival (OS). ResultsThe 3-year OS of all patients was 71.8 %. This increase of 3-year OS was associated with laparoscopic cases (r = 0.638, p = 0.047). Analysis of the CUSUM curve showed a significant change in the 3-year OS of 1400 cases. Further propensity score matching (PSM) of patients during and after the learning curve (<1400 and ≥ 1400 cases) showed a significant difference in the 3-year OS between the two groups (68.5 % vs. 72.3 %, p = 0.045). Cox regression analysis verified that in ≥1400 cases, prior laparoscopic surgery (p = 0.045), textbook outcome (TO) and the number of retrieved lymph nodes (LNs) were independent protective factors. The LN non-compliance rate was an independent risk factor. In contrast, the rate of TO and the median number of retrieved LNs were significantly higher after the learning curve (≥1400 cases). Furthermore, the rates of LN non-compliance were significantly lower (p < 0.05). ConclusionsIncreasing laparoscopic surgical experience is associated with surgical quality and prognostic improvement in patients with gastric cancer. But improvements in outcomes accrued slowly over a long period.

CUSUM learning curves: what they can and can't tell us.

There has been increased interest in assessing the surgeon learning curve for new skill acquisition. While there is no consensus around the best methodology, one of the most frequently used learning curve assessments in the surgical literature is the cumulative sum curve (CUSUM) of operative time. To demonstrate the limitations of this methodology, we assessed the CUSUM of console time across cohorts of surgeons with differing case acquisition rates while varying the total number of cases used to calculate the CUSUM. We compared the CUSUM curves of the average console times of surgeons who completed their first 20 robotic-assisted (RAS) cases in 13, 26, 39, and 52weeks, respectively, for their first 50 and 100 cases, respectively. This analysis was performed for prostatectomy (1094 surgeons), malignant hysterectomy (737 surgeons), and inguinal hernia (1486 surgeons). In all procedures, the CUSUM curve of the cohort of surgeons who completed their first 20 procedures in 13weeks demonstrated a lower slope than cohorts of surgeons with slower case acquisition rates. The case number at which the peak of the CUSUM curve occurs uniformly increases when the total number of cases used in generation of the CUSUM chart changes from 50 to 100 cases. The CUSUM analyses of these three procedures suggests that surgeons with fast initial case acquisition rates have less variability in their operative times over the course of their learning curve. The peak of the CUSUM curve, which is often used in surgical learning curve literature to denote "proficiency" is predictably influenced by the total number of procedures evaluated, suggesting that defining the peak as the point at which a surgeon has overcome the learning curve is subject to routine bias. The CUSUM peak, by itself, is an insufficient measure of "conquering the learning curve."

IMPACT OF FEMALE LABOR FORCE PARTICIPATION IN ECONOMIC DEVELOPMENT OF PAKISTAN

Purpose This paper tries to examine whether the labor force participation of the female population affects the growth of the economy. Methodology The sampling data was collected from the World Bank’s website from 1971 to 2018. The Johansen co-integration test and VECM model were used to examine the relationship between female labor force participation and economic development. Findings The result of the Johansen and Juselius Co-integration test showed the long-term relationship between Female Labor Force Participation and Economic Development. The finding also indicated that female labor force participation had a negative impact on GDP. The CUSUM stability test was used for the short-run stability adjustments. Results of the CUSUM stability test showed that the coefficients of ECM (-1) speed of adjustment were stable at a 5 percent significance level, there were no oscillations outside the critical level, and the CUSUM curve was above the origin line, which indicated the significance of our short-run dynamics. Conclusion The study concludes that female labor force participation has a significant negative impact on Pakistan’s GDP, this is due to societal and cultural norms as well as the religious dignity of women.

Learning Curve for Metastatic Liver Tumor Open Resection in Patients with Primary Colorectal Cancer: Use of the Cumulative Sum Method.

Background: Liver resections have become the first-line treatment for primary and metastatic tumors and, therefore, are considered a core aspect of surgical training. This study aims to evaluate the learning curve of the extent and safety of liver resection procedures for patients with metastatic colorectal cancer. Methods: This single tertiary center retrospective analysis includes 158 consecutive cases of small liver resection (SLR) (n = 107) and major liver resection (MLR) (n = 58) procedures. A cumulative sum control chart (CUSUM) method was used to investigate the learning curve. Results: The operative time, total blood loss level, and incidence of adverse effects showed a learning curve. For SLRs, the CUSUM curve for operative time and blood loss level peaked at the 19th and 17th case, respectively, while for MLRs, these curves peaked at the 28th and 24th case, respectively. The CUSUM curve for minor adverse effects (MAEs) and severe adverse effects (SAEs) showed a downward slope after the 16th and 68th procedures in the SLRs group and after the 29th and 39th procedures in the MLRs cohort; however, it remained within the acceptable range throughout the entire study. Conclusion: SLR procedures were performed faster with less intraoperative blood loss and shorter postoperative stays than MLRs, and a higher number of completed procedures was required to gain stabilization and repeatability in the operating time and intraoperative blood loss level. In MLR procedures, the reduction of SAEs was accomplished significantly later than the stabilization of the operative time and intraoperative blood loss level.

Ultrasound Block of the Medial Branch: Learning the Technique Using CUSUM Curves.

Background:Blocking the medial branch of the lumbar facet joints plays a fundamental diagnostic and therapeutic role in the treatment of lumbar pain. Attempts to replace the typical guided X-ray techniques with ultrasound-guided techniques have also involved treating the lumbar medial branches. By applying the cumulative sum control chart (CUSUM method), we sought to evaluate the learning curve associated with ultrasound-guided block of the lumbar medial branches in operators experienced in locoregional anesthesia but without expertise in pain therapy.Aim:This study aimed to use a repeatable method to identify the learning curve of the ultrasound-guided medial branch block.Settings and Design:This study was a prospective application of over forty consecutive procedures of ultrasound lumbar medial branch block.Materials and Methods:The ultrasound medial branch blocks were performed under ultrasound guidance with confirmation of correct positioning using fluoroscopy on a population of patients with low back pain with any body mass index (BMI).Statistical Analysis:The operator's performance was assessed using the learning curve cumulative summation test (LS-CUSUM).Results and Conclusions:The correct target was reached in 29 procedures out of a total of 40 (72.5%) and in 29 out of 36 procedures performed on patients with BMI <30 (80.5%). According to the CUSUM algorithm, 11 further consecutive successes would have been necessary (47 procedures in total) to achieve a proven learning of the technique in the group with only patients with a BMI <30, with a further 22 consecutive successes (62 procedures in total) in the general group. Ultrasound-guided block of the lumbar medial branch appears not to be optimal for training beginner/intermediate operators seeking to replace guided X-ray procedures with guided ultrasound.

Laparoscopic Radical Gastrectomy for Gastric Cancer: Long-Term Outcome and Critical Analysis of 10-Year Experience in a Teaching Center

Background: Laparoscopic surgical approaches for gastric cancer are increasing, yet limited evidence between the learning curve and long-term outcomes. To analyze survival in GC patients at a single center over 10 years and characterize the relationship between the learning curve and prognosis. Methods: This retrospective cohort study studied 3674 patients who underwent laparoscopic radical gastrectomy for gastric cancer. Cusum and Cox regression were used to assess the association between the surgeon’s experience and the 3 years overall survival (OS). Results: The 3-year OS of all patients was 71.8%. This increase of 3-year OS was associated with laparoscopic cases (r=0.638, p=0.047). Analysis of the CUSUM curve showed a significant change in the 3-year OS of 1400 cases. Further propensity score matching of patients during and after the learning curve (<1400 and ≥1400 cases) showed a significant difference in the 3-year OS between the two groups (68.5% vs. 72.3%, p=0.045). Cox regression analysis verified that in ≥1400 cases, prior laparoscopic surgery (p=0.045), textbook outcome (TO) and the number of retrieved lymph nodes (LNs) were the independent protective factor. The LN non-compliance rate was an independent risk factor. In contrast, the rate of TO and the median number of retrieved LNs were significantly higher after the learning curve (≥1400 cases). Furthermore, the rates of LN non-compliance were significantly lower (p<0.05). Conclusions: Increasing laparoscopic surgical experience is associated with surgical quality and prognostic improvement in patients with gastric cancer. But improvements in outcome accrued slowly over a long period. Funding: The study was sponsored by the Scientific and Technological Innovation Joint Capital Projects of Fujian Province (2017Y9011,2019Y9098). The Second Batch of Special Support Funds for Fujian Province Innovation and Entrepreneurship Talents (2016B013). Declaration of Interest: None to declare. Ethical Approval: The study was approved by IRB of our institute, Fujian Medical University.

Curvas de aprendizaje acumulado CUSUM en videolaringoscopia de valva angulada: estudio descriptivo

IntroductionVideolaryngoscopy is a recommended technique for airway management; however, an objective measure of training goal is required. MethodsDescriptive study of CUSUM curves, with 80% success rate, Alpha 0.1 error, Beta 0.1, with acceptable error values of 0.2, and unacceptable error of 0.31. ResultsCUSUM curves of 35 postgraduate students are described: 23 reached the minimum procedures and 13 reached the goal setted, with a median of 15 procedures (RIQ 11-19). Most students who did not complete the curve, had only one month of practice. ConclusionThe use of CUSUM curves could be helpful to individualize learning goals in technical skill.

Learning curve of robot-assisted middle pancreatectomy (RMP): experience of the first 100 cases from a high-volume pancreatic center in China.

Middle pancreatectomy (MP) is safe and feasible in patients with benign or low-grade malignant tumors located at the neck or proximal body of the pancreas. As a tissue-sparing operation, MP can preserve normal pancreatic function and reduce the risk of postoperative endocrine and exocrine insufficiency. However, the morbidity, especially the postoperative pancreatic fistula (POPF) rate, remains high. A robot-assisted surgical system may provide patients with less trauma; however, there are few reports on robot-assisted middle pancreatectomy (RMP). We describe the experience of RMP at our center to illustrate the learning curve (LC). From August 2010 to July 2017, 100 patients underwent RMP in the Pancreatic Disease Center of Shanghai Ruijin Hospital affiliated to Shanghai Jiaotong University School of Medicine. Patient characteristics, operative outcomes, and oncological outcomes were collected and analyzed. The CUSUM curve was analyzed according to operative time and estimated blood loss (EBL) and was used to describe the LC and identify the flexion points. Among the 100 patients who underwent RMP in our hospital, the mean age was 47.5 ± 14.2years, and 69 patients were female. From the CUSUM curve, we found two flexion points: cases 12 and 44. After 44 cases, the rate of improvement was much faster. We separated the patients into two groups based on the LC (cases 1-44 and cases 45-100). There were significant improvements in operative time (173.1 ± 44.7min vs. 137.3 ± 30.1min, p < 0.001) and EBL (103.4 ± 90.0ml vs. 69.3 ± 53.9ml, p = 0.021). The overall POPF rate was 32% (32/100), while the incidence rate of biochemical leakage was 14% (14/100). However, there was no significant difference in the risk of POPF or other complications between the two groups. The postoperative length of stay (LOS) was also not different. The 90-day mortality rate was 1%. From our long-term follow-up, pancreatic function was preserved in most patients, with only three cases of endocrine insufficiency and two cases of exocrine insufficiency. RMP was helpful and a good choice for the selected patients. PF was the main complication and has not been improved until now. There were two flexion points in the LC at cases 12 and 44. More cases are needed to gain more experience. A larger sample size and prospective studies are needed to verify the advantage of RMP.

Learning Curve of Totally Endoscopic Non Rib-spreading Mitral Valve Surgery

Objective: Minimally invasive mitral valve surgery has been shown to be transferable through proctoring and careful analysis of surgeons’ performance. Totally endoscopic mitral valve surgery without rib spreading represents an advancement in the mitral surgery field. As invasiveness decreases, technical demand increases and careful proctoring and monitoring is required. We use the CUSUM analysis to elucidate the performance and the learning curve of our group switching from standard minimally invasive mitral valve surgery to totally endoscopic approach. Methods: From July 2015 to April 2018, 177 patents underwent totally endoscopic mitral valve surgery. The procedure was adopted for “all-comers” patients with either isolated mitral and/or tricuspid valve disease. Euroscore II was used to the risk against which the surgical failure was compared to construct the CUSUM curve. Surgical failure was defned as: 1) perioperative death; 2)intraoperative conversion to sternotomy; 3) perioperative myocardial infarction (new Q- waves >0.04 ms and/or reduction in R-waves >25% in at least two contiguous leads on electrocardiogram); 4) perioperative aortc dissection; 5) stroke (defined as Rankin Modified scale score >= 6) in-hospital reoperation for any cause. Also we considered surgical procedure end-points of failure as the occurrence of one or more of the following: 1) cardiopulmonary bypass (CPB) time exceeding 95% of our “conventional MIMVS” CPB tme; 2) cross-clamp (X-clamp) time exceeding 95% of our conventional approach; 3) preparation time exceeding 95% of our current MIMVS setup. Results: Procedure specific risk adjusted probability of failure, probability of failure during preparation time, prolonged CPB time and prolonged cross clamp time were always in control. Conclusions: Between 50 and 60 procedures are required to reach the lower boundary to overcome procedure-specific risks, manage the surgical setup and be proficient in the new way of mitral repair as reflected by the cardiopulmonary bypass time and cross-clamping time.

Improving Outcomes Defending Patient Safety: The Learning Journey in Robotic Liver Resections.

Background While laparoscopy is currently adopted for hepatic resections, robotic approaches to the liver have not gained wide acceptance. We decided to analyze the learning curve in the field of robotic liver surgery comparing short-term outcomes between the first and the second half of our series. Methods We retrospectively reviewed demographics and clinical data of patients who underwent robotic liver resection at our institution from July 2014 through September 2017. 60 patients diagnosed with primary or secondary liver neoplasms or hydatid disease were included in this study. ASA PS >3, heart failure, respiratory insufficiency, and general contraindication to pneumoperitoneum were exclusion criteria. Results 60 patients were included. We observed a statistically significant decrease in operative time (p<0.001), intraoperative blood loss (p=0.01), and postoperative complications (p<0.001) after 30 cases. From the interpretation of the CUSUM curve, the time of operation appears to be significantly reduced after the first 30 operations. Discussion This is the first European analysis of the learning curve for robotic liver resection in an HPB and liver transplant referral center. However, more studies are needed to confirm such results outside a HPB referral center. This is crucial to develop formal credentialing protocols for both junior and senior surgeons.

Evaluation of the learning curve of transanal total mesorectal excision: single-centre experience.

IntroductionTransanal total mesorectal excision (TaTME) has been recently proposed to overcome the difficulties of the standard TME approach, allowing better visualization and dissection of the mesorectal fascia. Although TaTME seems very promising, the evidence and body of knowledge on achieving proficiency in performing it are still sparse.AimTo evaluate the learning curve of TaTME based on a single centre’s experience.Material and methodsConsecutive patients undergoing TaTME since 2014 in a tertiary referral department were included in the study. All procedures were performed by one experienced surgeon. CUSUM curve analyses were performed to evaluate learning curves.ResultsSixty-six patients underwent TaTME. After analysis of postoperative morbidity rate, intraoperative adverse effects and operative time, we estimated that 40 cases are needed to achieve TaTME proficiency. Subsequently, patients were divided into two groups: before (40 patients) and after overcoming the learning curve (26 patients). Group 1 had higher readmission (p = 0.041) and complication rates (p = 0.019). There were no statistically significant differences in terms of intraoperative adverse effects, length of stay or pathological quality of the specimen.ConclusionsTransanal total mesorectal excision is a promising yet technically demanding procedure and requires at least 40 cases to complete the learning curve. More data are needed to introduce it as a standard procedure for low rectal cancer treatment.

CUSUM charts in the quality control of colon cancer lymph node analysis: a population-registry study

BackgroundThe most important determinant of survival in patients with colon cancer is the presence or absence of regional lymph node metastases. This factor is consistently associated with long-term and disease-specific survival. Cumulative summation of differences (CUSUM) charts can help to discriminate abnormalities that cannot be explained by the general variability of a process. We used CUSUM charts to analyse the quality of nodal analysis in colon cancer and to use a population-registry cancer database to estimate the optimal number of lymph nodes for adequate prognostic analysis.MethodsThis was a multicentre population-registry cancer study from January 2004 to December 2007. We used these data to produce the different CUSUM curves, focusing on the main variables. To calculate survival, we used the Kaplan–Meier method.ResultsIn this study, we examined 548 patients. The CUSUM curves were calculated for overall mortality, specific mortality, and recurrence according to (1) the number of lymph nodes analysed and affected and (2) compared the ratio of the number of lymph nodes affected to the number analysed. Finally, the lymph node ratio was compared to the overall survival CUSUM curve.DiscussionThis CUSUM control chart analysis reinforces the unquestionable importance of analysing at least 12 lymph nodes in patients with colon cancer in order to accurately estimate their prognosis. However, our findings indicate that the analysis of at least 20 lymph nodes is a more appropriate cutoff point for accomplishing the demanding objective of diagnosing a high-quality prognosis in colon cancer patients.

Influence of Natural and Anthropogenic Linear Canopy Openings on Forest Structural Patterns Investigated Using LiDAR

In much of the commercial boreal forest, dense road networks and energy corridors have been developed to access natural resources with unintended and poorly understood effects on surrounding forest structure. In this study, we compare the effects of anthropogenic and natural linear openings on surrounding forest conditions in black spruce stands (gap fraction, tree and sapling height, and density). Forest structure within a 100 m band around the edges of anthropogenic (roads and power lines), natural linear openings (streams), and a reference black spruce forest was measured by identifying individual stems and canopy gaps on recent high density airborne LiDAR canopy height models. CUSUM curves were used to assess the distance of edge influence. Forests surrounding anthropogenic openings were found to be gappier, less dense, and have smaller trees than those around natural openings. Forests were denser around natural and anthropogenic linear openings than in the reference forest with edge effects observed up to 24–75 m and 18–54 m, respectively, into the forest. A high density of saplings in the gappier forests surrounding anthropogenic openings may eventually lead to a higher forest biomass in the zone area surrounding roads as is currently observed around natural openings.

Learning curve analysis of transapical NeoChord mitral valve repair.

Transapical off-pump mitral valve intervention with neochordae implantation is a novel, minimally invasive procedure for treatment of degenerative mitral valve regurgitation. The aim of this study was to apply control charts (CUSUM curves) to monitor the performance of NeoChord repair during the initial phase of its adoption. The first 112 consecutive patients who underwent NeoChord repair at our institution between November 2013 and March 2016 were included in the analysis. Mitral Valve Academic Research Consortium criteria for 1-year patient success was utilized to determine failed procedures. Control charts had predetermined acceptable and unacceptable failure rates of 5% and 15%, respectively. The actual incidence of 1-year-patient failure was 11% (12 of 112 cases), with a cluster of failures within the first 20 cases. The CUSUM analysis demonstrated an initial learning curve; however, the upper boundary (alarm line) was never crossed. The reassurance line was first crossed after 40 procedures and performance remained stable after 49 procedures. NeoChord repair is a safe procedure, and the results are maintained through the 1-year follow-up. A relative high number of implants were required to overcome the learning curve at our institution due to the concurrent development of patient selection criteria and the technical refinement of the procedure. Future studies are needed to assess the evolution of the learning curve after the wide adoption of the procedure across European and North American centres.

Cumulative sum analysis of the learning curve for endoscopic resection of juvenile nasopharyngeal angiofibroma.

To determine the learning curve with cumulative sum analysis for endoscopic resection of juvenile nasopharyngeal angiofibroma (JNA) and investigate whether the surgeon's expertise is a risk factor for recurrence. We reviewed the medical records of patients with JNA who underwent endoscopic or endoscopic-assisted surgery between 2006 and 2015. We used cumulative sum (Cusum) analysis to plot the learning curve for operation time versus chronological sequence, and verified the Cusum curve by risk-adjusted Cusum (RA-Cusum) analysis. We identified three phases of expertise. The recurrence rate was analyzed using the Kaplan-Meier method and log-rank tests. A multivariable Cox regression analysis was performed to identify the independent risk factors for recurrence. We included 154 JNA patients with a median age of 16years. The surgeon overcame the learning curve after case 80 with increasing surgical efficiency and competence. The learning curve plotted by Cusum analysis divided the cases into three phases: phase 1, accumulation of initial experience (cases 1-41); phase 2, further accumulation of experience (cases 42-117); and phase 3, mastering the procedure (cases 118-154). Pearson's χ2 tests showed that tumor stage (P = 0.021), blood loss (P = 0.001), operation time (P < 0.001), and phase (P < 0.001) were associated with recurrence. The log-rank test showed that time to recurrence was significantly shorter in phase 1 than in phases 2 and 3. Blood loss and phase were independently prognostic factors for time to recurrence, with P values of 0.023 and 0.009, respectively. The RA-Cusum analysis identified two inflection points of the curve at case 44 and 83, and verified the results of Cusum analysis. Surgical experience and competence with endoscopic resection affect the recurrence rate in JNA patients. 4.

A study of the learning curve for robotic oesophagectomy for oesophageal cancer.

Robot-assisted minimally invasive oesophagectomy (RAMIE) enables radical, meticulous dissection of the oesophagus and lymph nodes. Our goal was to identify the effect of the learning curve for RAMIE when performing radical upper mediastinal dissection in patients with oesophageal cancer. We conducted a retrospective review of a prospectively maintained database of patients who underwent RAMIE for oesophageal cancer between May 2008 and July 2016. The gain in proficiency for each postoperative outcome measure was presented using observed-expected cumulative sum (O-E CUSUM) curves. The change points were defined at the maximal distance from the zero axis. A total of 140 patients were included. Squamous cell carcinoma (n = 131, 93.6%) was the dominant type. Thirty-day and 90-day deaths occurred in 1 and 5 patients (0.7% and 3.6%, respectively). The change points of the risk-adjusted O-E CUSUM curves were similar to those of the unadjusted O-E CUSUM curves with the exception of those for thoracic procedure time and vocal cord palsy. The number of harvested lymph nodes increased from 25 to 45 before and after 30 cases. The vocal cord palsy rate decreased from 36% to 17% before and after 60 cases. The total operation time decreased from 496 min to 431 min; the length of the hospital stay decreased from 24 days to 14 days; and the anastomotic leakage rate decreased from 15% to 2% before and after 80 cases. Our study demonstrated a temporal improvement in postoperative outcomes based on accumulated experience with RAMIE. The risk-adjusted O-E CUSUM curves were similar to the unadjusted O-E CUSUM curves, which represents the significant impact of the effect of a learning period on the postoperative outcomes of RAMIE in patients with oesophageal cancer.

Application of CUSUM curve in cardiac surgery resident clinical training

Objective To investigate the application of CUSUM (cumulative sum control chart) curve in cardiac clinical teaching of resident surgeon education. Methods We chose a surgeon of 10 years work experience of attending the preparation operation of internal mammary artery as control reference (standard group, 28 patients) and a resident engaged in professional clinical cardiac work no more than 5 years as group 1, a professional training physician engaged in cardiac surgery clinical work more than 5 years as group 2 and took 40 patients' data respectively from the two groups' preparation of internal mammary artery operation. And then we recorded the postoperative mammary artery flow, internal mammary artery preparation time and adverse events data and made statistics analysis with SPSS 19.0, and CUSUM curve with Matlab R2012b polynomial curve. Results When the density of operate interval and the operate numbers came to about 25 cases, the polynomial curve's slope rate went up to 0, regardless the surgeons' experience, CUSUM value was accumulated from 66 to 76, and overcame the learning curve successfully. However, when the density of operate interval did no reach the standard, the surgeon's CUSUM ploynomial curve slope rate never reached to 0, and can't overcome the learning curve. Conclusion CUSUM curve gives a clear quantitative indicator to the cultivation of clinical physician, and makes teaching teachers can understand the young physicians' learning process, so as to change the teaching plan, help young physicians cross the learning curve as soon as possible. Key words: Cumulative sum control chart (CUSUM); Cardiac surgery; Residents; Learning curve

Learning Curve for Single-Incision Laparoscopic Anterior Resection for Sigmoid Colon Cancer

Compared with conventional laparoscopic surgery, single-incision laparoscopic surgery produces better cosmetic benefits. The aim of this study was to investigate the learning curve for single-incision laparoscopic anterior resection (SILAR) for sigmoid colon cancer using multidimensional methods. From September 2009 through May 2014, one hundred and thirteen patients underwent SILAR for sigmoid colon cancer by a single surgeon at Severance Hospital. The learning curve was analyzed using moving average, cumulative sum control chart (CUSUM), and risk-adjusted CUSUM methods. For risk-adjusted CUSUM, surgical failure was defined as conversion to open surgery or conventional laparoscopic surgery, morbidity within 30 days after surgery, <12 harvested lymph nodes, or local recurrence. Using the moving average method, the peak point for operation time occurred at the 65(th) case (173 minutes). The CUSUM method also showed the operation time peak point at the 65(th) case. However, the risk-adjusted CUSUM curve did not ascend after the 61st case. The operation time and hospital stay for the 60 phase 1 patients (cases 1 to 60) were longer than for 53 phase 2 patients (cases 61 to 113) (166.6 vs 140 minutes; p < 0.001 and 7.1 vs 5.5 days; p = 0.009). Phase 2 patients had a significantly larger tumor diameter and more harvested lymph nodes. The learning curve for SILAR for sigmoid colon cancer was 61 to 65 cases according to multidimensional statistical analyses. Single-incision laparoscopic anterior resection is feasible for surgeons experienced in laparoscopic surgery. However, SILAR required more cases for proficiency than the number previously reported for conventional laparoscopic surgery, likely because of its technical challenges.