Cumulative Sum Research Articles

Learning Curve of Novice Foot and Ankle Surgeon on Minimal Invasive Calcaneus Surgery Using the Sinus Tarsi Approach

Category: Trauma; Other Introduction/Purpose: Calcaneal fracture surgery represents one of the most challenging procedures for orthopedic surgeons. Recently, the use of the sinus tarsi approach for treating calcaneal fractures has been gaining popularity. Prior to this investigation, research was lacking on the learning curve of the sinus tarsi approach for calcaneal fracture surgeries among orthopedic surgeons newly initiating independent surgical practice. This study aims to delineate the learning curve of junior professors, who have recently completed their fellowship and are beginning to lead calcaneal fracture surgeries, using the sinus tarsi approach and its correlation with clinical outcomes, underscoring the critical importance of specialized surgical expertise. Methods: From October 2022 to January 2024, a total of 50 cases of calcaneal fractures, specifically Sanders types 3 and 4, treated surgically using the sinus tarsi approach at a single level 1 trauma center were analyzed to study the learning curve. The cutoff values for each parameter according to the number of surgical cases were analyzed using the cumulative sum test. The degree of correction for the Bohler angle, hindfoot varus angle, and posterior facet step-off was analyzed using preoperative and postoperative X-rays and Computed Tomography. Additionally, the number of C-arm fluoroscopy shots during surgery and the duration of the operation were examined. Postoperative complications, including infections, and the need for revision surgery were also analyzed. Results: The study included 23 cases of Sanders type 3 fractures and 27 cases of type 4 fractures. Significant improvements were observed with the Bohler angle increasing from an average of 12.2 degrees preoperatively to 26.3 degrees postoperatively, the hindfoot varus angle reducing from 15.2 degrees to 5.3 degrees, and the posterior facet step-off decreasing from 14.1mm to 0.56mm. The CUSUM for satisfactory correction of the Bohler angle and hindfoot varus was 21 cases each, and the posterior facet step off was 26 cases. The average duration of surgery was 104 minutes and the CUSUM was 24 cases. The average number of C-arm fluoroscopy shots during surgery was 141 and the CUSUM was 20 cases. Conclusion: As indicated by multidimensional statistical analyses, novice foot and ankle surgeon can achieve a plateau of proficiency after the initial learning period with 20 to 26 cases.

Multi-Stage Wiener Process Based Remaining Useful Life Prediction for Load Cells

Abstract Nowadays, sensor technology is used in a wide range of fields, and the demand for its reliability continues to increase. Accurate estimation of the remaining useful life of sensors is critical. Since the performance degradation of sensors involves multiple stages, the single-stage Wiener degradation model is difficult to accurately characterize. To resolve this issue, a multi-stage Wiener process degradation model is established. The model utilizes the cumulative sum algorithm to identify change points among stages. Then, the performance of the multi-stage Wiener model for characterizing degradation trends is validated with load cell accelerated aging test data. Furthermore, the results of experiment demonstrate that the proposed method provides a more accurate remaining useful life estimation compared to the single-stage Wiener model, and the relative error is reduced by 18.82%.

A randomised controlled trial of interventions to promote adoption of physical activity in adults with severe mental illness

Background and aimsAdults with severe mental illness (SMI) have lower physical activity (PA) than the general population. Supervised exercise interventions provide high support but may not effectively promote motivation, which is important for behaviour change. Motivational strategies such as PA counselling may target motivation more directly; however, the effectiveness in people with SMI is unclear. MethodsThis was a randomised controlled trial of interventions designed to promote PA in adults with SMI. Participants were randomised to either: (1) supervised exercise (GYM), or (2) motivational counselling and self-monitoring using fitness trackers (MOT). Group sessions were once/week over 8-weeks. The primary outcome was time spent in moderate-to-vigorous PA (MVPA) assessed using GENEActiv accelerometers worn continuously. Change in MVPA was assessed using the cumulative change from baseline, and as a composition of light activity, sedentary behaviour, and sleep. ResultsSixty-four participants were allocated (63% male, 82% overweight/obese, 59% psychotic disorder). Accelerometer-derived MVPA increased for the MOT group between baseline and post-intervention, and the cumulative sum of change in MVPA from baseline in the MOT group was higher than the GYM group. Compositional analyses showed stable weekly activity profiles, with no significant changes attributable to group allocation. ConclusionsThe cumulative change in MVPA was higher for MOT than GYM; however, compositional analyses that considers MVPA as a composition of other daily behaviours showed no change in composition over the intervention period. Exercise interventions should incorporate motivational strategies and supervised exercise; future research should investigate behaviour change interventions with longer durations and more frequent sessions. Registration detailsThe trial is registered under the Australian and New Zealand Clinical Trial Registry (ACTRN12617001017314).

The effect of climate change on the variation of low flow rates within mountainous basins: Case study of the Srou basin-Middle Atlas-Morocco (1976-2016)

Abstract The study of hydro-climatic variability over extended periods is crucial for comprehending the effects of climate variability on water resources and the incidence of droughts. In Morocco, drought has historically afflicted the plains, eastern, and southern regions of the country. However, the impact of drought in mountainous areas has often been overlooked. Climate change has exacerbated this situation, as evidenced by significant water deficits experienced by Morocco in 1982 and 2007. These events underscore the vulnerability of regions to drought, especially during periods of low-flow. This study focuses on examining rainfall variability within the Srou River basin, and its impact on fluctuations in low-flow rates in the context of a changing climate. The analysis utilizes the Cumulative Sum method to assess these dynamics. Besides, rainfall data and monthly low-flow rates were analysed and assessed. The obtained results reveal a significant variability in rainfall across the watershed, with a general trend of decline punctuated by occasional brief wet periods. These drought episodes have led to diminished surface and groundwater resources within the area. This research sheds light on the pressing need to address hydro-climatic challenges and underscores the urgency of adaptation measures to safeguard water security in Morocco’s diverse geographical contexts.

A Formal Language for Performance Evaluation Based on Reinforcement Learning

Temporal Logics are a rich variety of logical systems designed for specifying properties over time, and about events and changes in the world over time. Traditional temporal logic, however, is limited to binary outcomes true or false and lacks the capacity to specify performance properties of a system such as the maximum, minimum, or average costs between states. Current languages do not accommodate the quantification of such performance properties, especially in scenarios involving infinite execution paths where performance property like cumulative sums may fail to converge. To this end, this paper introduces a novel formal language aimed at assessing system performance, which encapsulates not only temporal dynamics but also various performance-related properties. In this study, this paper utilizes reinforcement learning techniques to compute the values of performance property formulas. Finally, in the experimental part, a formal language representation of system performance properties was implemented, and the values of the performance property formulas were computed using reinforcement learning. The effectiveness and feasibility of the proposed method were validated.

Overcoming the Learning Curve in Robot-Assisted Spinal Surgery—How Does It Compare to O-Arm Navigation?

Background: Robotic systems have the potential to significantly enhance the accuracy and outcomes of spinal surgery. Adopting this new technology requires an examination of its learning curve and influencing factors. This study analyzes the learning curve associated with using the Mazor X Stealth Edition system for pedicle screw placement and performs a matched-pair analysis to compare operative durations between robot-assisted and navigation-based surgeries, evaluating the efficiency of the robotic system. Methods: We collected retrospective operative data from patients who underwent robot-assisted pedicle screw placements between December 2020 and June 2024 and conducted a cumulative sum (CuSUM) analysis to assess the learning curve, focusing on the robotic system’s setup duration. Additionally, we compared a group of patients who underwent robot-assisted pedicle screw placements with a pair-matched group who underwent O-arm-based navigation-assisted pedicle screw placements. Results: There was a notable decrease in the robotic setup duration, with a significant shift in trend observed after the first 20 cases. While the initial setup time was 24 minutes, it reduced to 17 minutes in later cases, reflecting a marked improvement in efficiency as the surgeon gained more experience with the robot. Conclusion: Our findings indicate there were no added difficulties using the robotic system compared to the navigation system. Moreover, the learning curve for the robotic system can be quickly surmounted, and it offers clear advantages over previous systems, making it a valuable tool for pedicle screw application.

A weighted dual cumulative sum chart for monitoring the process mean

AbstractThe cumulative sum (CUSUM) charts are well‐structured and widely used for detecting small‐to‐moderate changes in the process parameters. However, their performance can be limited when the shift size is unknown or varies over time. Various methods have been developed to address this issue, including dual CUSUM (DCUSUM), adaptive CUSUM, adaptive EWMA, and weighted CUSUM charts, all of which offer better sensitivity compared to traditional CUSUM charts. In this study, we propose a new weighted DCUSUM chart designed to effectively detect the mean shifts in a normally distributed process. Monte Carlo simulations are used to estimate the zero‐state and steady‐state average run‐length (ARL) profiles of the control charts. The ARL performances of the control charts are evaluated in terms of expected relative ARL (ERARL) and expected weighted run‐length (EWRL). Our results show that the proposed chart may outperform existing counterparts in terms of the ARL, ERARL, and EWRL measures, indicating superior performance in detecting a range of the mean shift sizes. Finally, we apply the existing and proposed charts to a real dataset, showcasing their practical utility in process monitoring.

Unveiling change-point detection with ARMA-GARCH models

This paper delves into the asymptotic theory of a Cumulative Sum (CUSUM)-type test designed for detecting change points in the variance of AutoRegressive Moving-Average models, incorporating Generalized Autoregressive Conditional Heteroscedasticity innovations. We demonstrate that, under the null hypothesis (no change), the CUSUM test statistic converges to the supremum of a standard Brownian bridge. Using a Monte Carlo simulation, we highlight the strong performance of our proposed test when compared to the methods by Song and Kang. Furthermore, we provide a real-world data analysis to showcase the practical application of our test.

Learning curve for a five-step procedure, transthoracic single-port assisted laparoscopic transabdominal diaphragmatic approach, for Siewert type II adenocarcinoma of the esophagogastric junction

Objective: To investigate the learning curve for a five-step procedure, namely, a transthoracic single-port assisted laparoscopic transabdominal diaphragmatic approach, for Siewert type II adenocarcinoma of the esophagogastric junction. Methods: In this retrospective cohort study, we analyzed relevant clinical data of 66 patients with Siewert type II adenocarcinoma of the esophagogastric junction who had undergone the five-step procedure performed by the same surgeon in the Gastrointestinal Surgery Department of Guangdong Provincial Hospital of Chinese Medicine from May 2017 to April 2023. The learning curve were plotted using cumulative summation analysis and selected indicators, including intraoperative blood loss, duration of surgery, time to first flatus, time to first tolerance of liquid food, length of hospital stay, and incidence of perioperative complications at different stages were compared. The data were analyzed using SPSS 24.0 statistical software. Numerical data are presented as cases (%) and data were analyzed using the χ2 test or Fisher's exact test. Normally distributed measurement data are presented as x±s, and independent sample t-testing was performed for inter group comparison. Non-normally distributed measurement data are presented as M(Q1, Q3) and the Mann-Whitney U test was used for inter group comparison. Results: The five-step procedure had been successfully completed without switching to open surgery in all 66 study patients. There were no perioperative deaths, blood loss was 100 (50, 200) mL and duration of surgery 329.4±87.3 minutes. The equation of optimal fit for the duration of surgery was y=0.031x3-4.4757x2+164.97x-264.4 (P<0.001, R2=0.9797). The cumulative summation learning curve reached a vertex when 25 surgical procedures had accumulated. Using 25 cases as the cut-off, we divided the learning curves into learning and proficiency periods and patients into learning (25) and proficiency period groups (41). There were no statistically significant differences between the two groups of patients in sex, age, body mass index, American Society of Anesthesiologists score, history of abdominal surgery, comorbidities, preoperative neoadjuvant therapy, maximum tumor diameter, surgical procedure, or T and N stage of tumor (P>0.05). The following factors differed significantly (all P<0.05) between the learning and proficiency stages: in the latter there was less intraoperative blood loss (100 [50, 100] ml vs. 200 [100, 200] ml, U=-3.940, P<0.001), shorter duration of surgery ([289.8±50.7] minutes vs. [394.4±96.0] minutes, t=5.034, P<0.001), more mediastinal lymph nodes removed (5 [2, 8] vs. 2 [1, 5], U=-2.518, P=0.012), earlier time to first flatus (2 [2, 3] days vs. 4 [3, 6] days, U=-4.016, P<0.001), earlier time to first tolerance of liquid food (5 [4, 6] days vs. 7 [6, 8] days, U=-2.922, P=0.003), shorter duration of hospital stay (8 [8, 10] vs. 10 [9, 12] days, U=-2.028, P=0.043). The incidence of surgical complications did not differ significantly between the two groups (P=0.238). Conclusion: Satisfactory results can be achieved with the five-step procedure for patients with Siewert type II adenocarcinoma of the esophagogastric junction once 25 procedures have been performed.

Pharmacy School Affordability for Pharmacy Technicians From 2004 to 2022

ObjectiveThis study aimed to evaluate the trends in pharmacy technician wages relative to pharmacy school tuition and fees for the first professional year (P1) from 2004 to 2022, and to assess the affordability of pharmacy education for those currently employed as technicians in a pharmacy. MethodsThis observational cross-sectional study used data from the United States Bureau of Labor Statistics to calculate median disposable incomes for pharmacy technicians and the American Association of Colleges of Pharmacy Tuition Trends Database to calculate cumulative sums of P1 in-state tuition and mandatory fees for pharmacy students. The primary outcome was the national change in the tuition affordability ratio, defined as the comparison of median disposable income with median total tuition and fees for P1. Changes in the tuition affordability ratio for the most affordable programs in each state were analyzed as a secondary outcome. ResultsThe study found that from 2004 to 2022, the median disposable income of pharmacy technicians nationally increased from $20,103 to $33,255, while median P1 tuition and fees rose from $13,223 to $36,183. The median tuition affordability ratio decreased from 1.52 in the 2004–2005 academic year to 0.92 in 2022–2023, indicating a 40% reduction in affordability. State-specific analysis revealed varying affordability ratios, with only Pennsylvania and Rhode Island showing an increase in affordability. ConclusionThe study highlights a significant decline in the affordability of pharmacy education, raising concerns about the economic barriers faced by prospective pharmacy students and calling for a reevaluation of financial strategies within the field.

The Role of ICG-Guided Fluorescent Mode in Boosting the Learning Curve of Laparoscopic Cholecystectomy.

Background: The most common therapy for gallstones is laparoscopic cholecystectomy (LC). How to help young residents avoid bile duct injuries (BDI) during surgery and grasp LC seems to be a paradox. Methods: We retrospectively reviewed 145 cases of LC operated by two residents under indocyanine green (ICG)-guided mode or normal LC procedures to illustrate the role of ICG mode in boosting the LC learning curve. The clinic data were analyzed by logistic regression, receiver operator curve tests, Cumulative Sum (CUSUM), and Risk-Adjusted Cumulative Sum (RA-CUSUM) analysis. Results: The operation failure rate is similar. However, operation time under ICG mode is shorter than that under normal mode. The peak at the 49th case represented the normal resident's complete mastery of the surgery, while the peak point of ICG mode appeared at the 36th case in the fitting curve. The most significant cumulative risk (peak point) of operation failure of LC was at the 35th case in ICG LC mode, while it appeared in the 49th in normal LC mode. Conclusions: Owing to the advantage of real-time imaging and the stable success rate of cholangiography, ICG-guided LC helps residents shorten the operation time, boost the learning curve, and manage to control the operation failure rate.

Model-based fault detection algorithm for liquid hydrogen refueling system using CUSUM method

The global focus on the role of hydrogen energy in achieving carbon neutrality is increasing, particularly in transportation. Establishing and operating hydrogen refueling stations for fuel cell electric vehicles (FCEVs) are gaining prominence. This study proposes a model-based fault detection algorithm to enhance safety at large-capacity liquid hydrogen (LH2) refueling stations. First, the LH2 refueling system is modeled using Aspen HYSYS, estimating the heat transfer coefficient of the storage tank to meet the normal evaporation rate (NER) specification of 0.9 % per day. Second, diverse fault scenarios are identified via a Hazard and Operability Study (HAZOP), and simulation data are generated for the normal and fault scenarios. Finally, a fault detection algorithm utilizing the cumulative summation (CUSUM) is developed, with its threshold determined by risk levels analyzed in HAZOP. This allowed for tighter fault detection as risk levels increased. The algorithm successfully identified faults for all 11 scenarios.

Free‐roaming horses exceeding appropriate management levels affect multiple vital rates in greater sage‐grouse

AbstractSince the passage of the Wild Free‐Roaming Horses and Burros Act of 1971, federal agencies have been responsible for managing free‐roaming equids in the United States. Over the last 20 years, management has been hampered by direct opposition from advocacy groups, budget limitations, and a decline in the public's willingness to adopt free‐roaming horses (Equus caballus). As a result, free‐roaming equid numbers have increased to &gt;3 times the targeted goal of 26,785 (horses and burros [E. asinus] combined), the cumulative sum of the appropriate management levels (AML) for all 177 designated herd management areas (HMA) managed by the Bureau of Land Management. This increase is one of the causes of greater sage‐grouse (Centrocercus urophasianus) population declines, owing to habitat alteration from free‐roaming equids exacerbated by ongoing drought. To evaluate potential demographic mechanisms influencing these declines, we compiled survival data from 4 studies in central Wyoming, USA, including 995 adult female (first‐year breeders or older) sage‐grouse during the breeding season, 1,075 nests, 372 broods, and 136 juveniles (i.e., overwinter survival for fledged young), from 2008–2022. During this period, we also obtained population information for free‐roaming horses from 9 HMAs used by individual grouse in our sample. Population estimates of free‐roaming horses for these HMAs ranged from 59% to 7 times of the maximum appropriate management level (AMLmax). Sage‐grouse monitored outside of HMAs represented control populations and, because we assumed they were not exposed to populations of free‐roaming horses, we set values of AMLmax to zero for all grouse located outside of HMAs. To evaluate whether free‐roaming horses were negatively affecting sage‐grouse, we modeled daily survival of breeding age females, nest, broods, and juveniles. There was strong or moderate evidence that overabundant free‐roaming horses negatively affected nest, brood, and juvenile survival. When horse abundance increased from AMLmax to 3 times AMLmax, survival was reduced 8.1%, 18.3%, 18.2%, and 18.2% for nests, early broods (≤20 days after hatch), late broods (&gt;20 days to 35 days after hatch), and juveniles, respectively. These results indicate increasing free‐roaming horse numbers affected vital rates for important life stages of sage‐grouse, and that maintaining free‐roaming horse numbers below AMLmax would reduce negative effects to sage‐grouse populations.

Evaluation of a voluntary passive surveillance component in cattle through notification of excess mortality

Passive surveillance can be most effective in the early detection of disease outbreaks given that farmers observe their animals daily. The European Animal Health Law states that unexplained excess mortality should be reported to the veterinary authorities. In the Netherlands, in addition to notifications to the competent authority, Royal GD is commissioned a passive surveillance component that consists of a veterinary helpdesk and postmortem examination for early detection of emerging diseases. The aim of this study was to evaluate this voluntary passive surveillance component through excess mortality in cattle.Weekly on-farm mortality was calculated using the cattle Identification and Registration records. Mortality was assessed on regional level for dairy, veal and other beef cattle using a Generalized Linear Model (GLM) (log-link, negative binomial). We used a cumulative sum of the model residuals to identify periods of excess mortality. The mortality was defined as excessive when above five times the standard error. The analysis was also conducted on herd level, but these models did not converge.We checked for an association between the two passive surveillance components elements and excess mortality. A GLM (log-link, negative binomial) with the number of contacts or submissions per region as the dependent variables and excess mortality per region and year as independent variables was carried out.Overall, the models showed significantly higher use of passive surveillance components in periods of excess mortality compared to non-excess periods. In dairy cattle the odds for contact or submission were between 1.72 (1.59–1.86) and 2.02 (1.82–2.25). For veal calves we found the odds of 2.19 (1.18–4.04) and 2.24 (1.78–2.83) relative to periods without excess mortality. Beef cattle operations, other than veal, showed only an increased odds for postmortem submissions in calves of 3.71 (2.74–5.01), submissions for cattle and contact in general was not increased for this farm type.In conclusion, the voluntary passive surveillance component in the Netherlands is used more often in periods of excess mortality in cattle. The chance of getting a timely response is highest for dairy farms. For veal calf operations the chance of receiving a timely response is more likely for postmortem submissions. A comparison with passive surveillance for excess mortality in other countries was not possible because no literature could be found. However, the method of this study can be used by other countries to evaluate their passive surveillance. This would make comparison of the performance of passive surveillance in different countries possible.

Improvement and application of back random response detection: Based on cumulative sum and change point analysis.

In educational and psychological assessments, benefiting from back random response (BRR) is a major type of rapid guessing in misfitting item score patterns. Person-fit statistics (PFS) based on cumulative sum (CUSUM) and change point analysis (CPA) from statistical process control (SPC) are better than other PFS for detecting aberrant response. In this study, we developed new person-fit statistics based on three algorithms from CPA procedure and CUSUM method for detection of person misfit with dichotomous or polytomous items. By means of simulated data, the effectiveness of the new statistics to detect test-takers with BRR was investigated.

Memory-type time-between-events charts using nonhomogeneous Poisson process

The traditional time-between-events (TBE) control charts are developed in non-adaptive fashion assuming the Poisson process, where the TBE follows the exponential distribution. However, in many situations we need an adaptive strategy, especially for healthcare or system monitoring. The focus of this study is to introduce new exponentially weighted moving average and cumulative sum adaptive TBE control charts for high-quality processes based on nonhomogeneous Poisson process by assuming the power law intensity. Charts assuming the nonhomogeneous Poisson process are dynamic and can be used where the underlying failure rate may be changing over time. The performance of the proposed control charts is evaluated using the average run length and coefficient of variation of the run length distribution. Three real data examples which correspond to different shape parameters of the power law process are also discussed in the article.

Efficient ARL estimation for general control charts using censored run lengths

The average run length (ARL), the average number of in-control signals before an out-of-control signal occurs, is a critical measure of the performance of a control chart. Various methods have been explored for estimating the ARL, including Markov chain-based approximation, integration method, and the Monte Carlo method, especially for time-dependent charting statistics. Although computationally expensive, the Monte Carlo method is generic and applicable to all control charts. Typically, it involves choosing the maximum run length in advance and discarding iterations that fail to produce out-of-control signals to accommodate some unusually lengthy runs. However, these discarded runs provide information for estimating the run length. This paper introduces a new Monte Carlo approximation that retains failed iterations as Type I censored observations for ARL estimation. Our approach relies on the memoryless expectation of the run length distribution to have a simple and efficient ARL estimator. This assumption is necessary for mean estimation in Type I censored data and aligns with existing ARL approximations used in popular control charts like Shewhart, exponentially weighted moving average (EWMA), and cumulative sum (CUSUM) charts. Numerical simulations demonstrate our method’s computational and statistical efficiency across the mean, median, EWMA, and CUSUM charts.

Novel drainage pipeline breakages detection based on MEMS inertial sensor: From mechanism to application

Urban water environment pollution is a global concern, in developing countries, sewage infiltration resulting from urban drainage pipelines breakage is an essential element in the urban groundwater pollution and the recurrence of black odor water bodies, it is crucial to accurately and efficiently detection and localisation of urban drainage pipelines breakage to protect the urban water resources. In this paper, a device for detecting defects in drainage pipelines was developed and assembled using microelectromechanical systems (MEMS) inertial sensors as the core components, and the improved cumulative sum (CUSUM) model was used for anomalous detection of the pitch angle of the device's movement along the course of the pipeline as a method of detecting pipeline breakage. In the laboratory simulation of drainage pipeline tests, the CUSUM peaks (0.709, 1.102, 3.038, 7.990) for the case of external water infiltration rates into the pipeline at the point of pipe breakage (2.9%, 4.6%, 5.8%, 9.2%), and for the cases of sewer exfiltration rates in the pipeline of 4.2% and 6.4% (0.760, 1.382). CFD simulations of the water flow in the laboratory pipeline show a high degree of overlap between the trend of the water surface near the point of breakage and the anomalous fluctuations in the pitch angle of the device motion in the laboratory tests. Finally, the authors tested the device on municipal drains in the city of A. The results demonstrated the reliability and high accuracy of the device. The device enables to improve the ecological quality of urban water environment by accelerating the rate of defect detection in urban drainage pipelines and reducing the detection expenses.

Triphasic Learning Curve of Cytoreductive Surgery with Hyperthermic Intraperitoneal Chemotherapy.

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is an effective but costly procedure for select patients with peritoneal malignancies. The impact of progression along a learning curve on the cost of these procedures is unknown. We performed a retrospective cohort study of patients undergoing CRS-HIPEC from 2016 to 2022 at a single quaternary center. Our study cohort was temporally divided into four equally sized volume quartiles (A, B, C, and D). We utilized cumulative sum plots and split-group analysis to characterize the institutional learning curve based on cost, operative time, length of stay, and morbidity. Multivariable linear regression was performed to estimate costs after adjusting for covariates. Bivariate analysis was performed using a Kruskal-Wallis test to compare continuous variables and a χ2 test to compare categorical variables. Of 201 patients, the median age [interquartile range (IQR)] was 57 (47-65) years, 113 (56%) patients were female, 143 (71%) were white, and 107 (53%) had private insurance. Median operating room charge [US$42,639 (US$32,477-54,872), p < 0.001] varied between volume quartiles, peaking in quartile C. Stabilization was achieved for 86 cases for operating room cost, 88 cases for routine cost, 96 cases for length of stay, 103 cases for operative time, 120 cases for intensive care unit length of stay, and 150 cases for overall and serious morbidity. The actual operating room and routine costs were similar to predicted costs at the end of the study period. The CRS-HIPEC learning curve is triphasic, with cost stability achieved relatively early compared with other markers of surgical proficiency.

The learning curve for modified hand-assisted retroperitoneoscopic living donor nephrectomy

BackgroundWe aimed to introduce our modified hand-assisted retroperitoneoscopic living donor nephrectomy (HARPLDN) technique and define the learning curve.MethodsOne hundred thirty-eight kidney donors who underwent modified HARPLDN by the same surgeon between May 2015 and March 2022 were included. A cumulative sum (CUSUM) learning curve analysis was performed with the total operation time as the study outcome.ResultsIn total, the mean operative time was 138.2 ± 32.1 min. The median warm ischemic time (WIT) and estimated blood loss were 90 s and 50 ml, respectively. The learning curve for the total operative time was best modeled as a second-order polynomial with the following equation: CUSUMOT (min) = (–0.09 case number2) + (12.88 case number) – 67.77 (R2 = 0.7875; p<0.05). The CUSUM learning curve included the following three unique phases: phase 1 (the initial 41 cases), representing the initial learning curve; phase 2 (the middle 43 cases), representing expert competence; and phase 3 (the final 54 cases), representing mastery. The overall 6-month graft survival rate was 99.3%, with 94.9% immediate onset of graft function without delayed graft function and 0.7% ureteral complications.ConclusionsOur modified method is safe and effective for living donor nephrectomy and has the advantages of a shorter operating time and optimized WIT. The surgeon can become familiar with the modified HARPLDN after 41 cases and effectively perform the next 97 cases.