The external validation of a difficulty scoring system for predicting the risk of intraoperative complications during laparoscopic liver resection

The impact of obesity on short-term outcomes after the laparoscopic liver resection: a single-institution experience

Introduction

Obesity is a major public health problem and a well-known cause of multiple comorbidities. With the increasing application of minimally invasive surgery for benign and malignant liver lesions, the results of laparoscopic liver resection (LLR) in obese patients are of great interest.

Aim

To evaluate the short-term operative outcomes after LLR in obese patients and compare them to patients with normal weight and overweight.

Material and methods

All 235 consecutive patients undergoing LLR from 2008 to 2023 were retrospectively analysed. Patients were categorized into 3 groups based on their body mass index (BMI): normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2). The groups were then compared regarding preoperative data and intra- and postoperative outcomes.

Results

Despite higher ASA score and associated comorbidities in the obese group, there were no significant differences in intraoperative complication (blood loss, damage to surrounding structures, conversion rate) between BMI groups (20.8% vs. 16.8% vs. 22.7%, p = 0.619). There were no significant differences in overall morbidity (34.7% vs. 27.7% vs. 29.5%, p = 0.582), as well as major morbidity (15.9% vs. 11.8% vs. 11.4%, p = 0.784) or mortality rates (1.4% vs. 1.7% vs. 0.0%, p = 1.000). Univariate logistic regression did not show BMI or obesity as a predictive variable for intraoperative complication.

Conclusions

Obesity is not a significant, strong risk factor for worse short-term outcomes, and LLR may be considered also in patients with overweight and obesity.

Ranking as a Procedure for Selecting a Replacement Variable in the Score Predicting the Survival of Patients Treated with Curative Intent for Colorectal Liver Metastases

Background and Objectives: The issue of a missing variable precludes the external validation of many prognostic models. For example, the Liverpool score predicts the survival of patients undergoing surgical therapy for colorectal liver metastases, but it includes the neutrophil-lymphocyte ratio, which cannot be measured retrospectively. Materials and Methods: We aimed to find the most appropriate replacement for the neutrophil-lymphocyte ratio. Survival analysis was performed on data representing 632 liver resections for colorectal liver metastases from 2000 to 2020. Variables associated with the Liverpool score, C-reactive protein, albumins, and fibrinogen were ranked. The rankings were performed in four ways: The first two were based on the Kaplan-Meier method (log-rank statistics and the definite integral IS between two survival curves). The next method of ranking was based on univariate and multivariate Cox regression analyses. Results: The ranks were as follows: the radicality of liver resection (rank 1), lymph node infiltration of primary colorectal cancer (rank 2), elevated C-reactive protein (rank 3), the American Society of Anesthesiologists Classification grade (rank 4), the right-sidedness of primary colorectal cancer (rank 5), the multiplicity of colorectal liver metastases (rank 6), the size of colorectal liver metastases (rank 7), albumins (rank 8), and fibrinogen (rank 9). Conclusions: The ranking methodologies resulted in almost the same ranking order of the variables. Elevated C-reactive protein was ranked highly and can be considered a relevant replacement for the neutrophil-lymphocyte ratio in the Liverpool score. These methods are suitable for ranking variables in similar models for medical research.

A machine learning analysis of difficulty scoring systems for laparoscopic liver surgery

INTRODUCTION

In the last decade, several difficulty scoring systems (DSS) have been proposed to predict technical difficulty in laparoscopic liver resections (LLR). The present study aimed to investigate the ability of four DSS for LLR to predict operative, short-term, and textbook outcomes.

METHODS

Patients who underwent LLR at a single tertiary referral center from January 2014 to June 2020 were included in the present study. Four DSS for LLR (Halls, Hasegawa, Kawaguchi, and Iwate) were investigated to test their ability to predict operative and postoperative complications. Machine learning algorithms were used to identify the most important DSS associated with operative and short-term outcomes.

RESULTS

A total of 346 patients were included in the analysis, 28 (8.1%) patients were converted to open surgery. A total of 13 patients (3.7%) had severe (Clavien-Dindo ≥ 3) complications; the incidence of prolonged length of stay (> 5 days) was 39.3% (n = 136). No patients died within 90 days after the surgery. According to Halls, Hasegawa, Kawaguchi, and Iwate scores, 65 (18.8%), 59 (17.1%), 57 (16.5%), and 112 (32.4%) patients underwent high difficulty LLR, respectively. In accordance with a random forest algorithm, the Kawaguchi DSS predicted prolonged length of stay, high blood loss, and conversions and was the best performing DSS in predicting postoperative outcomes. Iwate DSS was the most important variable associated with operative time, while Halls score was the most important DSS predicting textbook outcomes. No one of the DSS investigated was associated with the occurrence of complication.

CONCLUSIONS

According to our results DDS are significantly related to surgical complexity and short-term outcomes, Kawaguchi and Iwate DSS showed the best performance in predicting operative outcomes, while Halls score was the most important variable in predicting textbook outcome. Interestingly, none of the DSS showed any correlation with or importance in predicting overall and severe postoperative complications.

External validation of different difficulty scoring systems of laparoscopic liver resection for hepatocellular carcinoma

BACKGROUND

Several difficulty scoring systems (DSSs) have been proposed for evaluating difficulty of laparoscopic liver resection (LLR) and no study has validated their performance in a hepatocellular carcinoma (HCC)-only cohort at the same time.

METHODS

All cases with HCC that underwent LLR from January 2015 to December 2020 in our center were retrospectively collected. Performance of the IWATE-DSS, Halls-DSS, Hasegawa-DSS, and Kawaguchi-DSS in predicting perioperative outcomes was evaluated. Subgroup analyses were conducted to compare perioperative outcomes between surgeons on the learning curve and surgeons that have gone through the learning curve.

RESULTS

For all four DSSs, there were significant distributions of applying bleeding control, surgical time, estimated blood loss, postoperative major complications, and postoperative hospital stay among different groups of each DSS (P all < 0.05). Conversion to laparotomy or not was significantly distributed in different groups of the IWATE-DSS (P = 0.006) and Halls-DSS (P = 0.022), while it was not in the Hasegawa-DSS (P = 0.056) and Kawaguchi-DSS (P = 0.183). Trend tests showed that the conversion rates increased with higher DSS points in the IWATE-DSS (P < 0.001) and the Kawaguchi-DSS (P = 0.021), while not in the Halls-DSS (P = 0.064) and the Hasegawa-DSS (P = 0.068). In the medium and advanced/expert difficulty-level subgroups defined by the IWATE-DSS, there were larger estimated blood loss (P in medium-difficulty group = 0.009; P in the advanced/expert difficulty group = 0.004) and longer postoperative hospital stay (P in the medium-difficulty group = 0.012; P in the advanced/expert group = 0.035) in the learner-performed cases.

CONCLUSIONS

All DSSs performed well in predicting applying bleeding control, surgical time, estimated blood loss, postoperative major complications, and postoperative hospital stay, while only the IWATE-DSS was able to predict whether conversion to laparotomy or not for HCC patients underwent LLR. The IWATE-DSS was also able to help surgeons on the LLR learning curve choose cases and guide clinical practices.

The learning curve of laparoscopic liver resection utilising a difficulty score

BACKGROUND

This study aimed to quantitatively evaluate the learning curve of laparoscopic liver resection (LLR) of a single surgeon.

PATIENTS AND METHODS

A retrospective review of a prospectively maintained database of liver resections was conducted. 171 patients undergoing pure LLRs between April 2008 and April 2021 were analysed. The Halls difficulty score (HDS) for theoretical predictions of intraoperative complications (IOC) during LLR was applied. IOC was defined as blood loss over 775 mL, unintentional damage to the surrounding structures, and conversion to an open approach. Theoretical association between HDS and the predicted probability of IOC was utilised to objectify the shape of the learning curve.

RESULTS

The obtained learning curve has resulted from thirteen years of surgical effort of a single surgeon. It consists of an absolute and a relative part in the mathematical description of the additive function described by the logarithmic function (absolute complexity) and fifth-degree regression curve (relative complexity). The obtained learning curve determines the functional dependency of the learning outcome versus time and indicates several local extreme values (peaks and valleys) in the learning process until proficiency is achieved.

CONCLUSIONS

This learning curve indicates an ongoing learning process for LLR. The proposed mathematical model can be applied for any surgical procedure with an existing difficulty score and a known theoretically predicted association between the difficulty score and given outcome (for example, IOC).

A scoring system to predict surgical difficulty in minimally invasive surgery for gastric submucosal tumors

BACKGROUND

Various minimally invasive surgery (MIS) procedures are used for gastric submucosal tumors (SMTs), and their technical difficulties vary. Preoperative understanding of difficulties is crucial; however, objective indicators are lacking.

METHODS

Gastric SMTs requiring MIS (n = 36) were retrospectively analyzed. Preoperative factors were evaluated using a multivariate linear regression analysis. A scoring system was then constructed, and its feasibility was evaluated.

RESULTS

Three factors were identified and scored based on the weighted contribution for predicting surgical time: tumor location (cardia, score of "2"; posterior wall of fundus, "1"); tumor size (greater than 4 cm, "1"); and tumor growth appearance (intraluminal, "1"). The summed scores could stratify the surgical time stepwise in each score, and patients who scored higher than 3 had larger intraoperative blood loss and a longer hospital stay.

CONCLUSION

Our scoring system predicted surgical difficulties and may, therefore, be useful in selecting appropriate surgical approaches for gastric SMTs.

Comparing practice and outcome of laparoscopic liver resection between high-volume expert centres and nationwide low-to-medium volume centres

BACKGROUND

Based on excellent outcomes from high-volume centres, laparoscopic liver resection is increasingly being adopted into nationwide practice which typically includes low-medium volume centres. It is unknown how the use and outcome of laparoscopic liver resection compare between high-volume centres and low-medium volume centres. This study aimed to compare use and outcome of laparoscopic liver resection in three leading European high-volume centres and nationwide practice in the Netherlands.

METHOD

An international, retrospective multicentre cohort study including data from three European high-volume centres (Oslo, Southampton and Milan) and all 20 centres in the Netherlands performing laparoscopic liver resection (low-medium volume practice) from January 2011 to December 2016. A high-volume centre is defined as a centre performing >50 laparoscopic liver resections per year. Patients were retrospectively stratified into low, moderate- and high-risk Southampton difficulty score groups.

RESULTS

A total of 2425 patients were included (1540 high-volume; 885 low-medium volume). The median annual proportion of laparoscopic liver resection was 42.9 per cent in high-volume centres and 7.2 per cent in low-medium volume centres. Patients in the high-volume centres had a lower conversion rate (7.4 versus 13.1 per cent; P < 0.001) with less intraoperative incidents (9.3 versus 14.6 per cent; P = 0.002) as compared to low-medium volume centres. Whereas postoperative morbidity and mortality rates were similar in the two groups, a lower reintervention rate (5.1 versus 7.2 per cent; P = 0.034) and a shorter postoperative hospital stay (3 versus 5 days; P < 0.001) were observed in the high-volume centres as compared to the low-medium volume centres. In each Southampton difficulty score group, the conversion rate was lower and hospital stay shorter in high-volume centres. The rate of intraoperative incidents did not differ in the low-risk group, whilst in the moderate-risk and high-risk groups this rate was lower in high-volume centres (absolute difference 6.7 and 14.2 per cent; all P < 0.004).

CONCLUSION

High-volume expert centres had a sixfold higher use of laparoscopic liver resection, less conversions, and shorter hospital stay, as compared to a nationwide low-medium volume practice. Stratification into Southampton difficulty score risk groups identified some differences but largely outcomes appeared better for high-volume centres in each risk group.

Evaluation of the Iwate Model for Predicting the Difficulty of Laparoscopic Liver Resection: Does Tumor Size Matter?

BACKGROUND

This study aimed to externally validate the Iwate scoring model and its prognostic value for predicting the risks of intra- and postoperative complications of laparoscopic liver resection.

METHODS

Consecutive patients who underwent pure laparoscopic liver resection between 2008 and 2019 at a single tertiary center were included. The Iwate scores were calculated according to the original proposition (four difficulty levels based on six indices). Intra- and postoperative complications were compared across difficulty levels. Fitting the obtained data to the cumulative density function of the Weibull distribution and a linear function provided the mean risk curves for intra- and postoperative complications, respectively.

RESULTS

The difficulty levels of 142 laparoscopic liver resections were scored as low, intermediate, advanced, and expert level in 41 (28.9%), 53 (37.3%), 32 (22.5%), and 16 (11.3%) patients, respectively. Intraoperative complications were detected in 26 (18.3%) patients and its rates (2.4%, 7.5%, 34.3%, and 62.5%) increased gradually with statistically significant values among difficulty levels (P ˂ 0.001). Major postoperative complications occurred in 21 (14.8%) patients and its rates (4.8%, 5.6%, 28.1%, 43.7%; P ˂ 0.001) showed the same trend as for intraoperative complications. Then, the mean risk curves of both complications were obtained. Due to outliers, a new threshold for a tumor size index was proposed at 38 mm. The repeated analysis showed improved results.

CONCLUSIONS

The Iwate scoring model predicts the probability of complications across difficulty levels. Our proposed tumor size threshold (38 mm) improves the quality of the prediction. The model is upgraded by a probability of complications for every difficulty score.

Validation and comparison of the Iwate, IMM, Southampton and Hasegawa difficulty scoring systems for primary laparoscopic hepatectomies

BACKGROUND

Various difficulty scoring systems (DSS) have been formulated to grade the complexity of laparoscopic hepatectomies (LH). This study aims to externally validate and compare 4 contemporary DSS including the Iwate, Institut Mutualiste Montsouris (IMM), Southampton and Hasegawa DSS in predicting the intraoperative technical difficulty and postoperative outcomes after LH.

METHODS

Retrospective review of 548 consecutive patients who underwent LH of which 455 met the study inclusion criteria. Outcomes measures of technical difficulty included operation time, Pringles maneuver, blood loss and blood transfusion rate. Postoperative outcomes measured included morbidity, major morbidity and postoperative hospital stay.

RESULTS

There was a statistically significant progressive increase in blood loss, blood transfusion rate, operation time and postoperative stay associated with all 4 DSS. There was also good calibration with respect to blood loss, operation time, Pringles maneuver, open conversion rate, postoperative morbidity, postoperative major morbidity and postoperative stay for all 4 DSS. The Southampton score demonstrated the poorest calibration in terms of operation time and discrimination in terms of application of Pringles maneuver and major morbidity amongst all 4 systems.

CONCLUSION

All 4 DSS significantly correlated with outcome measures associated with intraoperative technical difficulty and postoperative outcomes. The Southampton DSS was the poorest system in our cohort of patients.