Ten-Year Native Liver Survival Rate After Laparoscopic and Open Kasai Portoenterostomy for Biliary Atresia

Biliary atresia

Biliary atresia (BA) is a progressive inflammatory fibrosclerosing disease of the biliary system and a major cause of neonatal cholestasis. It affects 1:5,000-20,000 live births, with the highest incidence in Asia. The pathogenesis is still unknown, but emerging research suggests a role for ciliary dysfunction, redox stress and hypoxia. The study of the underlying mechanisms can be conceptualized along the likely prenatal timing of an initial insult and the distinction between the injury and prenatal and postnatal responses to injury. Although still speculative, these emerging concepts, new diagnostic tools and early diagnosis might enable neoadjuvant therapy (possibly aimed at oxidative stress) before a Kasai portoenterostomy (KPE). This is particularly important, as timely KPE restores bile flow in only 50-75% of patients of whom many subsequently develop cholangitis, portal hypertension and progressive fibrosis; 60-75% of patients require liver transplantation by the age of 18 years. Early diagnosis, multidisciplinary management, centralization of surgery and optimized interventions for complications after KPE lead to better survival. Postoperative corticosteroid use has shown benefits, whereas the role of other adjuvant therapies remains to be evaluated. Continued research to better understand disease mechanisms is necessary to develop innovative treatments, including adjuvant therapies targeting the immune response, regenerative medicine approaches and new clinical tests to improve patient outcomes.

Postoperative outcomes of acute-on-chronic liver failure in infants and children with biliary atresia

INTRODUCTION

Acute-on-chronic liver failure (ACLF) is associated with increased mortality and morbidity in patients with biliary atresia (BA). Data on impact of ACLF on postoperative outcomes, however, are sparse.

METHOD

We performed a retrospective analysis of patients with BA aged <18 years who underwent LT between 2011 and 2021 at our institution. ACLF was defined using the pediatric ACLF criteria: ≥1 extra-hepatic organ failure in children with decompensated cirrhosis.

RESULTS

Of 107 patients (65% female; median age 14 [9-31] months) who received a LT, 13 (12%) had ACLF during the index admission prior to LT. Two (15%) had Grade 1; 4 (30%) had Grade 2; and 7 (55%) had Grade ≥3 ACLF. ACLF cohort was younger at time of listing (5 [4-8] vs. 9 [6-24] months; p < .001) and at LT (8 [8-11] vs. 16 [10-40] months, p < .001) compared to no-ACLF group. Intraoperatively, ACLF patients had higher blood loss (40 [20-53] vs. 10 [6-19] mL/kg; p < .001) and blood transfusion requirements (33 [21-69] vs. 18 [7-25] mL/kg; p = .004). Postoperatively, they needed higher vasopressor support (31% vs. 10.6%; p = .04) and had higher total hospital length of stay (106 [45-151] vs. 13 [7-30] days; p = .023). Rate of return to the operating room, hospital readmission rates, and 1-year post-LT survival rates were comparable between the groups.

CONCLUSION

Despite higher perioperative complications, survival outcomes for ACLF in BA after LT are favorable and comparable to those without ACLF. These encouraging data reiterate prioritization during organ allocation of these critically ill children for LT.

Predictive model containing gene signature and shear wave elastography to predict patient outcomes after Kasai surgery in biliary atresia

AIMS

Infants with biliary atresia (BA) are treated with Kasai portoenterostomy (KPE) surgery, but many BA patients need subsequent salvage liver transplants. The aim of this study is to develop a comprehensive gene-clinical model based on two-dimensional shear wave elastography (2DSWE), liver gene expression, and other clinical parameters to predict response to KPE for BA patients.

METHODS

Differentially expressed gene patterns between liver samples of BA (n = 102) and non-BA control (n = 14) were identified using RNA sequencing analysis. Biliary atresia patients were then randomly assigned to training and validation cohorts. Gene classifier based on the differentially expressed genes was built in the training cohort. Nomogram models with and without gene classifier were further constructed and validated for predicting native liver survival of BA patients. The utility of the nomograms was compared by C-index.

RESULTS

Using the least absolute shrinkage and selection operator model, we generated a nine-gene prognostic classifier. The nomogram based on the nine-gene classifier, age, preoperative 2DSWE, and albumin had the better C-index compared to gene classifier alone in the training cohort (0.83 [0.76-0.90] vs. 0.69 [0.61-0.77], p = 0.003) and the validation cohort (0.74 [0.67-0.82] vs. 0.62 [0.55-0.70], p = 0.001). Using risk scores developed from the nomogram, the 12-month survival rates of BA patients with native liver were 35.7% (95% confidence interval [CI], 22.7-56.3) in the high-risk group and 80.8% (95% CI, 63.4-100.0) in the low-risk group in the validation cohort.

CONCLUSIONS

The comprehensive genetic-clinical nomogram based on preoperative 2DSWE, liver gene expression, and other clinical parameters can accurately predict response to KPE.

Laparoscopic versus open portoenterostomy for treatment of biliary atresia: a meta-analysis

OBJECTIVE

Our goal was to compare laparoscopic portoenterostomy versus open portoenterostomy for the treatment of biliary atresia.

MATERIALS AND METHODS

Using the databases EMBASE, PubMed, and Cochrane, we carried out a thorough literature search up to 2022. Studies comparing laparoscopic and open surgery for the treatment of biliary atresia were included.

RESULTS

Twenty-three studies comparing laparoscopic portoenterostomy (LPE) (n = 689) and open portoenterostomy (OPE) (n = 818) were considered appropriate for meta-analysis. Age at surgery time was lower in the LPE group than OPE group (I² = 84%), (WMD - 4.70, 95% CI - 9.14 to - 0.26; P = 0.04). Significantly decreased blood loss (I² = 94%), (WMD - 17.85, 95% CI - 23.67 to - 12.02; P < 0.00001) and time to feed were found in the laparoscopic group (I² = 97%), (WMD - 2.88, 95% CI - 4.71 to - 1.04; P = 0.002). Significantly decreased operative time was found in the open group (I² = 85%), (WMD 32.52, 95% CI 15.65-49.39; P = 0.0002). Weight, transfusion rate, overall complication rate, cholangitis, time to drain removal, length of stay, jaundice clearance, and two-year transplant-free survival were not significantly different across the groups.

CONCLUSIONS

Laparoscopic portoenterostomy provides advantages regarding operative bleeding and the time to begin feeding. No differences in remain characteristics. Based on the data presented to us by this meta-analysis, LPE is not superior to OPE in terms of overall results.

Laparoscopic versus open Kasai procedure for biliary atresia: long-term results of a randomized clinical trial

PURPOSE

The role of the laparoscopic approach for the Kasai procedure in the management of biliary atresia is still controversial. The aim of this study is to compare the long-term results of the laparoscopic Kasai procedure (LKP) to the open Kasai procedure (OKP).

METHODS

A randomized clinical trial was carried out from October 2009 to March 2017. Patients diagnosed with biliary atresia type III were randomized into 2 groups: one group underwent LKP and the other group-OKP. All the surgical procedures were performed by the same surgeon with the same technical principles. The long-term outcomes were compared between the two groups.

RESULTS

61 patients underwent LKP and 61 patients-OKP, with a median age at the surgery of 79.7 days. The two groups had no significant differences regarding the patients' baseline characteristics. At follow-up up to 142 months, the jaundice-free rate at the 6th postoperative month for LKP and OKP was 52.5% and 60.7%, respectively (p = 0.23). The 10-year cumulative survival after LKP tended to be inferior to OKP, respectively 44.3% vs. 58.9% (p = 0.09).

CONCLUSIONS

In this study, the long-term results of LKP tended to be inferior compared to OKP although the differences were not significant.

Robotic-assisted Kasai portoenterostomy for biliary atresia

BACKGROUND

Robotic-assisted Kasai portoenterostomy (RAKPE) has been utilized to treat biliary atresia (BA). However, RAKPE is not widely performed and its efficacy remains unknown. We summarized the experience of RAKPE for BA and determined its efficacy.

MATERIALS AND METHODS

We retrospectively analyzed 25 consecutive infants with non-syndromic type III BA who received RAKPE in our center from January 2020 to July 2021. RAKPE is a three-arm setup and four-trocar operation. Bipolar coagulation was used to dissect the small blood vessels at the hepatic portal. The fibrous cone was shallowly transected with bending electric scissors, followed by gelatin sponge compression to staunch the hemorrhage. Finally, a wide anastomosis was accurately constructed. Demographics and outcomes were recorded.

RESULTS

The mean operative time was 211.64 ± 18.93 min. No conversion to laparotomy or intraoperative complications occurred. The mean estimated blood loss was 7.64 ± 2.43 mL. Enteral feeding was resumed after 3.44 ± 1.23 days. All patients achieved bile excretion postoperatively, and dark green bile-stained stools were passed 1.50 days (range 1.00-3.00 days) after surgery. The average postoperative length of hospital stay was 10.32 ± 2.59 days. The jaundice clearance (JC) rate was 76.00% within 6 months after surgery and the incidence of cholangitis was 48.00% within 1 year following surgery. The survival with native liver (SNL) rate was 80.00% at 1 year and 66.67% at 2 years.

CONCLUSION

RAKPE can be regarded as a treatment option for patients with BA due to the good outcomes reported. However, long-term studies comparing open or laparoscopic approaches are needed.

Advances in the Treatment of Neonatal Biliary Disease

This article discusses current standard of care in neonatal biliary disease, particularly management of biliary atresia and choledochal cysts. It highlights surgical considerations, guidelines for adjuvant therapies, and promising therapeutic options that are under investigation.

Native liver survivors of portoenterostomy for biliary atresia with excellent outcome: redefining "successful" portoenterostomy

PURPOSE

Native liver survivors (NLS) after portoenterostomy (PE) for biliary atresia (BA) with normal biomarkers defined as total bilirubin (T-Bil), aspartate aminotransferase (AST)/alanine aminotransferase (ALT) for liver function (LF), cholinesterase (ChE), platelet count (PC), and absence of portal hypertension (PHT) were reviewed to redefine "successful" PE.

METHODS

92 post-PE BA patients were classified as NLS-1: normal biomarkers, PHT (-); NLS-2: at least one abnormal biomarker, PHT (-); NLS-3: normal biomarkers, PHT ( +); NLS-4: abnormal biomarkers, PHT ( +) and reviewed for a maximum 32 years.

RESULTS

As of June 2022, 55/92 (59.8%) had received liver transplants and 37/92 (40.2%) were NLS. NLS patients were classified as excellent outcome (EO): NLS-1 (n = 10; 27.0%) or non-EO: NLS-2: (n = 8; 21.6%), NLS-3: (n = 6; 16.2%), and NLS-4: (n = 13; 35.1%). Compared with non-EO, EO had PE earlier (50.5 versus 65 days; not significant; p = 0.08), significantly earlier onset of symptoms (13 days versus 32 days; p = 0.01) and significantly shorter jaundice-clearance (JC; 34.5 days versus 56.0 days; p < 0.001). Durations of follow-up were similar: 13 years in EO, 18.5 years in NLS-2, 20 years in NLS-3, and 15 years in NLS-4.

CONCLUSION

Incidence of "successful" PE or EO is low and correlated with early onset of symptoms and quicker JC.

Laparoscopic versus Open Pediatric Surgery: Three Decades of Comparative Studies

INTRODUCTION

 Despite its wide acceptance, the superiority of laparoscopic versus open pediatric surgery has remained controversial. There is still a call for well-founded evidence. We reviewed the literature on studies published in the last three decades and dealing with advantages and disadvantages of laparoscopy compared to open surgery.

MATERIALS AND METHODS

 Studies comparing laparoscopic versus open abdominal procedures in children were searched in PubMed/MEDLINE. Reports on upper and lower gastrointestinal as hepatobiliary surgery and on surgery of pancreas and spleen were included. Advantages and disadvantages of laparoscopic surgery were analyzed for different types of procedures. Complications were categorized using the Clavien-Dindo classification.

RESULTS

 A total of 239 studies dealing with 19 types of procedures and outcomes in 929,157 patients were analyzed. We identified 26 randomized controlled trials (10.8%) and 213 comparative studies (89.2%). The most frequently reported advantage of laparoscopy was shorter hospital stay in 60.4% of studies. Longer operative time was the most frequently reported disadvantage of laparoscopy in 52.7% of studies. Clavien-Dindo grade I to III complications (mild-moderate) were less frequently identified in laparoscopic compared to open procedures (80.3% of studies). Grade-IV complications (severe) were less frequently reported after laparoscopic versus open appendectomy for perforated appendicitis and more frequently after laparoscopic Kasai's portoenterostomy. We identified a decreased frequency of reporting on advantages after laparoscopy and increased reporting on disadvantages for all surgery types over the decades.

CONCLUSION

 Laparoscopic compared with open pediatric surgery seems to be beneficial in most types of procedures. The number of randomized controlled trials (RCTs) remains limited. However, the number of reports on disadvantages increased during the past decades.

Biliary Atresia: A Complex Hepatobiliary Disease with Variable Gene Involvement, Diagnostic Procedures, and Prognosis

The diagnosis of biliary atresia is still terrifying at the 3rd decade of the 21st century. In a department of neonatal intensive care unit, parents and physicians face a challenge with a jaundiced baby, who may or may not have a surgically correctable hepatopathy. The approach has been systematically evaluated, but the etiology remains ambiguous. The study of families with recurrent biliary atresia has been undertaken at a molecular level. The primary interest with this disease is to identify the etiology and change the treatment from symptomatic to curative. The occurrence of this obstructive cholangio-hepatopathy in well-known genetic syndromes has suggested just coincidental finding, but the reality can be more intriguing because some of these diseases may have some interaction with the development of the intrahepatic biliary system. Several genes have been investigated thoroughly, including ADD3 and GPC1 shifting the interest from viruses to genetics. In this review, the intriguing complexities of this hepatobiliary disease are highlighted.

Comparative study of open and laparoscopic Kasai portoenterostomy in children undergoing living donor liver transplantation for biliary atresia

PURPOSE

The effectiveness of laparoscopic Kasai portoenterostomy (Laparoscopic-KPE) for biliary atresia (BA) has been reported but remains controversial. We reviewed our own cases and cases described in previous studies of liver transplantation (LT) for BA after Laparoscopic-KPE to investigate the efficacy of Laparoscopic-KPE.

METHODS

Subjects were children of  ≤ 2 years old with LT for BA after KPE who underwent Laparoscopic-KPE (n = 10) or Open-KPE (n = 115) between 2009 and 2020. Propensity score matching was performed to reduce the effect of treatment selection bias. The clinical data regarding the preoperative characteristics and surgical results were compared.

RESULTS

The rates of hypoplastic portal vein and retrograde portal vein flow were lower in the Laparoscopic-KPE group than in the Open-KPE group (0 vs. 40.0%, p = 0.02 and 0 vs. 35.0%, p = 0.04). There was no marked difference in the operation time or duration of hepatectomy. For portal vein reconstruction, a vein graft was not required in the Laparoscopic-KPE group (0 vs. 35.0%, p = 0.03). No patients in the Laparoscopic-KPE group developed portal vein complications or required re-laparotomy for bowel perforation or re-bleeding, in contrast to the Open-KPE group (0 vs. 15.0% and 0 vs. 10.0%, respectively).

CONCLUSION

Laparoscopic-KPE may reduce postoperative complications that necessitate re-laparotomy in LT.

Laparoscopic vs open portoenterostomy in biliary atresia: a systematic review and meta-analysis

Hepatoportoenterostomy remains the cornerstone of treatment for biliary atresia. Current employed techniques include laparoscopy and open surgery. This study aims to determine if either method provides an advantage. Following PRISMA guidelines, a systematic review was conducted. Nineteen studies were included. Mean operative time 34.98 (95% CI 20.10, 49.85; p ≤ 0.00001) was longer in laparoscopic while bleeding volumes - 16.63 (95% CI - 23.39, - 9.86; p ≤ 0.00001) as well as the time to normal diet - 2.42 (95% CI - 4.51, - 0.32; p = 0.02) were lower in the laparoscopic group. No differences were observed in mean length of stay - 0.83. Similar complication, transfusions, postoperative cholangitis 0.97, and transplant free survival rates 1.00 (0.63, 1.60; p = 0.99) were seen between groups. Laparoscopic portoenterostomy provides advantages on operative time and bleeding as well as to normal diet when compared to open procedures. Both procedures showed no differences in length of stay, complications, cholangitis, and importantly, native liver survival. Level of evidence: III.

The incidence of different forms of ileus following surgery for abdominal birth defects in infants: a systematic review with a meta-analysis method

Objectives

Ileus following surgery can arise in different forms namely as paralytic ileus, adhesive small bowel obstruction or as anastomotic stenosis. The incidences of these different forms of ileus are not well known after abdominal birth defect surgery in infants. Therefore, this review aims to estimate the incidence in general between abdominal birth defects.

Content

Studies reporting on paralytic ileus, adhesive small bowel obstruction or anastomotic stenosis were considered eligible. PubMed and Embase were searched and risk of bias was assessed. Primary outcome was the incidence of complications. A meta-analysis was performed to pool the reported incidences in total and per birth defect separately.

Summary

This study represents a total of 11,617 patients described in 152 studies of which 86 (56%) had a follow-up of at least half a year. Pooled proportions were calculated as follows; paralytic ileus: 0.07 (95%-CI, 0.05–0.11; I 2=71%, p≤0.01) ranging from 0.14 (95% CI: 0.08–0.23) in gastroschisis to 0.05 (95%-CI: 0.02–0.13) in omphalocele. Adhesive small bowel obstruction: 0.06 (95%-CI: 0.05–0.07; I 2=74%, p≤0.01) ranging from 0.11 (95% CI: 0.06–0.19) in malrotation to 0.03 (95% CI: 0.02–0.06) in anorectal malformations. Anastomotic stenosis after a month 0.04 (95%-CI: 0.03–0.06; I 2=59%, p=0.30) ranging from 0.08 (95% CI: 0.04–0.14) in gastroschisis to 0.02 (95% CI: 0.01–0.04) in duodenal obstruction. Anastomotic stenosis within a month 0.03 (95%-CI 0.01–0.10; I 2=81%, p=0.02) was reviewed without separate analysis per birth defect.

Outlook

This review is the first to aggregate the known literature in order approximate the incidence of different forms of ileus for different abdominal birth defects. We showed these complications are common and the distribution varies between birth defects. Knowing which birth defects are most at risk can aid clinicians in taking prompt action, such as nasogastric tube placement, when an ileus is suspected. Future research should focus on the identification of risk factors and preventative measures. The incidences provided by this review can be used in those studies as a starting point for sample size calculations.

Impact of Age of Patient and Experience of Surgeon on the Outcome after Kasai Portoenterostomy: Can We Delay the Surgery?

INTRODUCTION

 Age of patient and experience of biliary atresia (BA) center are well-known factors associated with early jaundice clearance (EJC) after Kasai portoenterostomy (KPE) in infants with BA. This study focused on the impact of age and surgeon factor on the short-term outcome after KPE within a single center.

MATERIALS AND METHODS

 Fifty-four consecutive infants (18 boys and 36 girls) who underwent KPE from January 2010 to January 2020 were reviewed. KPE was performed in the earliest available operative session once the initial work-up was completed. In group A (n = 41), KPE was performed by surgeon A. In group B (n = 13), KPE was performed by specialists under the supervision of surgeon B (who is the mentor of surgeon A) when surgeon A was not available for operation. The demographics of patients, the EJC (total bilirubin <20 μmol/L within 6 months of KPE), and 2-year native liver survival (NLS) between the two groups were studied.

RESULTS

 The median age at operation was 52 days (range 26-135 days). The overall EJC rate and 2-year NLS were 85.2 and 89.4%, respectively. Group A (p = 0.015) and male gender (p = 0.029) were statistically associated with EJC but not the age at operation (p = 0.101). Group A was also statistically associated with superior 2-year NLS (p = 0.047).

CONCLUSION

 Balancing between the impact of age at operation and the experience of surgeon on the outcome after KPE, our result suggested that KPE may be deferred until a more experienced surgeon to operate.

Experience of treating biliary atresia with laparoscopic-modified Kasai and laparoscopic conventional Kasai: a cohort study

BACKGROUND

Complete mobilization of the left and right portal veins had been seldom utilized in the laparoscopic Kasai procedures. The purpose of this study was to evaluate the feasibility and efficacy of the key technique in detail.

METHODS

A total of 82 patients with type III biliary atresia were operated by laparoscopic Kasai at our hospital during January 2012 to October 2019. Forty-two patients underwent modified laparoscopic Kasai (group 1), and 40 patients of control group underwent general laparoscopic Kasai (group 2). The clinical data between the two groups were compared.

RESULTS

The early clearance of jaundice was significantly higher for group 1 (88.1%) versus group 2 (68.4%) (P < 0.05), the incidence of repeated cholangitis was significantly lower in group 1 (11.9%) versus group 2 (31.6%) (P < 0.05). The native liver survival rate was (85.7%) in group1 versus in group 2 (65.8%) (P < 0.05). In addition, there were no significant differences regarding the resumption oral intake and the post-operative hospital stay in the two groups.

CONCLUSION

The key technique of the complete mobilization of the left and right portal veins would improve the outcome of biliary atresia treated by laparoscopic Kasai.

Cholangitis in Patients With Biliary Atresia Receiving Hepatoportoenterostomy: A National Database Study

INTRODUCTION

Biliary atresia (BA) is a progressive form of liver disease in the neonatal period usually requiring hepatoportoenterostomy (HPE). Cholangitis is a common sequelae of HPE but data about which patients are at risk for this complication are limited.

OBJECTIVE

The objective of the study was to determine risk factors associated with cholangitis in a large retrospective cohort after HPE.

METHODS

The Pediatric Health Information System (PHIS) was queried for BA (ICD-9 975.61) and HPE (ICD-9-CM 51.37) admissions from 2004 to 2013. We performed univariate analysis and linear regression with dependent variables of ≥ 2 or ≥ 5 episodes of cholangitis, and independent variables of age at time of HPE, race, ethnicity, gender, insurance, ursodeoxycholic acid (UDCA) use, steroid use, presence of esophageal varices (EV), and portal hypertension (PH).

RESULTS

We identified 1112 subjects with a median age at HPE of 63 days and median number of cholangitis episodes of 2 within 2 years. On multiple regression analysis, black race (odds ratio (OR) 1.51, P = 0.044) and presence of PH (OR 2.24, P < 0.001) were associated with increased risk of ≥ 2 episodes of cholangitis, whereas HPE at >90 days was associated with less risk (OR 0.46, P = 0.001). Among those with ≥5 episodes, Asian race (OR 2.66, P = 0.038), public insurance (OR 1.72, P = 0.043), EV (OR 1.81, P = 0.017), and PH (OR 2.88, P < 0.001) were associated with higher risk.

CONCLUSIONS

Complications, such as cholangitis remain a common problem for patients, after HPE, with median of 2 episodes within 2 years. Higher rates of cholangitis are associated with portal hypertension whereas lower rate is associated with age at HPE of >90 days. Asians, patients with public insurance, and those with portal hypertension are more likely to have recurrent cholangitis.

Laparoscopic Kasai portoenterostomy is advantageous over open Kasai portoenterostomy in subsequent liver transplantation

BACKGROUND

Native liver survival after laparoscopic Kasai portoenterostomy (Lap-PE) for biliary atresia (BA) is controversial. We examined whether a jaundice-free native liver survival rate is comparable between conventional Kasai portoenterostomy (Open-PE) and Lap-PE. Then, the impact of the two types of PE on subsequent living-donor liver transplantation (LTx) was addressed in this study.

METHODS

The jaundice-free rate in 1- and 2-year-old patients who underwent Open-PE and Lap-PE from January 2006 to December 2017 was investigated. Additionally, perioperative data (duration from the start of surgery to the completion of hepatectomy and others) of patients aged 2 years or younger who underwent LTx after either Open-PE or Lap-PE from 2006 to 2017 were evaluated.

RESULTS

Thirty-one (67%) out of 46 Open-PE patients and 23 (77%) out of 30 Lap-PE patients showed native liver survival with jaundice-free status at 1 year of age (p = 0.384); 29 (63%) out of 46 Open-PE patients and 19 (70%) out of 27 Lap-PE patients showed native liver survival with jaundice-free status at 2 years of age (p = 0.524); there were no significant differences. Additionally, there were 37 LTx cases after PE within 2 years of birth, including 29 Open-PE and 8 Lap-PE cases. The patients in the Lap-PE group had fewer adhesions and significantly shorter durations of surgery up to the completion of the recipient's hepatectomy and durations of post-LTx hospital stay compared to the Open-PE group. There were no differences in blood loss or duration of stay in intensive care unit between the Lap-PE and Open-PE groups.

CONCLUSIONS

Jaundice-free native liver survival rate has been comparable between Open-PE and Lap-PE. Lap-PE resulted in fewer adhesions, contributing to better outcomes of subsequent LTx compared to Open-PE.