Establishment of Standards for the Referral of Large Non-Pedunculated Colorectal Polyps: An International Expert Consensus Using a Modified Delphi Process.

BACKGROUND AND AIMS: Resection of colorectal polyps has been shown to decrease the incidence and mortality of colorectal cancer. Large non-pedunculated colorectal polyps are often referred to expert centres for endoscopic resection, which requires relevant information to be conveyed to the therapeutic endoscopist to allow for triage and planning of resection technique. The primary objective of our study was to establish minimum expected standards for the referral of LNPCP for potential ER. METHODS: A Delphi methodology was employed to establish consensus on minimum expected standards for the referral of large colorectal polyps among a panel of international endoscopy experts. The expert panel was recruited through purposive sampling, and three rounds of surveys were conducted to achieve consensus, with quantitative and qualitative data analysed for each round. RESULTS: A total of 24 international experts from diverse continents participated in the Delphi study, resulting in consensus on 19 statements related to the referral of large colorectal polyps. The identified factors, including patient demographics, relevant medications, lesion factors, photodocumentation and the presence of a tattoo, were deemed important for conveying the necessary information to therapeutic endoscopists. The mean scores for the statements ranged from 7.04 to 9.29 out of 10, with high percentages of experts considering most statements as a very high priority. Subgroup analysis by continent revealed some variations in consensus rates among experts from different regions. CONCLUSION: The identified consensus statements can aid in improving the triage and planning of resection techniques for large colorectal polyps, ultimately contributing to the reduction of colorectal cancer incidence and mortality.

Impact of COVID-19 Infection on Pancreato-Biliary Diseases Requiring Endoscopic Retrograde Cholangiopancreatography.

BACKGROUND: Viral infections are known to impact the pancreato-biliary system; however, there are limited data showing that the same is true of COVID-19. Endoscopic retrograde cholangiopancreatography (ERCP) can safely be performed in patients with COVID-19 infection, but outcomes of patients with COVID-19 infections and concomitant pancreatic and biliary disease requiring endoscopic intervention are unknown. AIMS: This study aims to evaluate the severity of pancreaticobiliary diseases and post-ERCP outcomes in COVID-19 patients. METHODS: Patients with pancreato-biliary disease that required inpatient ERCP from five centers in the United States and South America between January 1, 2020, and October 31, 2020 were included. A representative cohort of patients from each month were randomly selected from each site. Disease severity and post-ERCP outcomes were compared between COVID-19 positive and COVID-19 negative patients. RESULTS: A total of 175 patients were included: 95 COVID positive and 80 COVID negative. Mean CTSI score for the patients who had pancreatitis was higher in COVID-positive cohort by 3.2 points (p < .00001). The COVID-positive group had more cases with severe disease (n = 41) versus the COVID-negative group (n = 2) (p < .00001). Mortality was higher in the COVID-19 positive group (19%) compared to COVID-negative group (7.5%) even though the COVID-19-negative group had higher incidence of malignancy (n = 17, 21% vs n = 7, 7.3%) (p = 0.0455). CONCLUSIONS: This study shows that patients with COVID infection have more severe pancreato-biliary disease and worse post-ERCP outcomes, including longer length of stay and higher mortality rate. These are important considerations when planning for endoscopic intervention. CLINICALTRIALS: gov: (NCT05051358).

Technical details and outcomes of peroral endoscopic myotomy with fundoplication: the first U.S. experience (with video).

BACKGROUND AND AIMS: Peroral endoscopic myotomy (POEM) is an established endoscopic treatment for achalasia; however, post-POEM rates of GERD remain a significant cause of concern. Single-session POEM with fundoplication (POEM-F) to treat achalasia was recently described to reduce post-POEM GERD. This study aims to report the technical feasibility, safety, and early outcomes of the first U.S. cohort of POEM-F. METHODS: We retrospectively reviewed all patients with achalasia treated with POEM-F at our center. The primary endpoint was technical success, defined as the successful completion of all steps of the POEM-F procedure. RESULTS: Six patients (mean age, 50 ± 4.8 years; 1 woman) underwent POEM-F for achalasia. Technical success was achieved in all patients (6/6), and no major immediate or delayed (up to 30 days postprocedure) adverse events were seen. At the 1-month follow-up visit, the mean Eckardt score decreased from 8.8 ± 1.1 to .3 ± .5. The GERD health-related quality of life and reflux symptom index scores obtained at the 1-month follow-up, with patients on proton pump inhibitors, were 2.3 ± 3.7 and 2.2 ± 2.5, respectively. CONCLUSIONS: This first case series on POEM-F in the United States suggests that POEM-F is feasible and safe with excellent short-term outcomes.

Incidence and risk factors for recurrence of ampullary adenomas after endoscopic papillectomy: Comparative analysis of familial adenomatous polyposis and sporadic ampullary adenomas in an international multicenter cohort.

OBJECTIVES: Endoscopic papillectomy (EP) is a minimally invasive therapy for the management of ampullary adenomas (AA). We conducted this multicenter study to assess the incidence of and factors related to the recurrence of AA after EP in patients with familial adenomatous polyposis (FAP) compared to sporadic AA. METHODS: We included patients who underwent EP for AA at 10 tertiary hospitals. Adenomatous tissue at the resection site at the time of surveillance endoscopies was considered recurrent disease. RESULTS: In all, 257 patients, 100 (38.9%) with FAP and 157 (61%) patients with sporadic AA, were included. Over a median of 31 (range, 11-61) months, recurrence occurred in 48/100 (48%) of patients with FAP and 58/157 (36.9%) with sporadic AA (P = 0.07). Two (2%) FAP patients and 10 (6.3%) patients with sporadic AA underwent surgery for recurrence. On multivariable regression analysis, the recurrence in FAP was higher than in sporadic patients after the first year of follow-up. AA size (hazard ratio [HR] 1.03, 95% confidence interval [CI] 1.001, 1.056), periampullary extension (HR 2.5, 95% CI 1.5, 4.01), and biliary duct dilation (HR 2.04, 95% CI 1.2, 3.4) increased the risk, while en bloc resection (HR 0.6, 95% CI 0.41, 0.9) decreased the risk of recurrence. CONCLUSION: Recurrence rates are high after EP. Most recurrences in sporadic patients occur within the first year of follow-up, but after the first year of follow-up in patients with FAP. Recurrences are higher with larger adenomas, biliary duct dilation, and periampullary extensions, and may be mitigated by en bloc resection. These factors should be considered in decision-making with the patients.

Zenker's peroral endoscopic myotomy, or flexible or rigid septotomy for Zenker's diverticulum: a multicenter retrospective comparison.

BACKGROUND: Treatment of Zenker's diverticulum has evolved from open surgery to endoscopic techniques, including flexible and rigid endoscopic septotomy, and more recently, peroral endoscopic myotomy (Z-POEM). This study compared the effectiveness of flexible and rigid endoscopic septotomy with that of Z-POEM. METHODS: Consecutive patients who underwent endoscopic septotomy (flexible/rigid) or Z-POEM for Zenker's diverticulum between 1/2016 and 9/2019 were included. Primary outcomes were clinical success (decrease in Dakkak and Bennett dysphagia score to ≤ 1), clinical failure, and clinical recurrence. Secondary outcomes included technical success and rate/severity of adverse events. RESULTS: 245 patients (110 females, mean age 72.63 years, standard deviation [SD] 12.37 years) from 12 centers were included. Z-POEM was the most common management modality (n = 119), followed by flexible (n = 86) and rigid (n = 40) endoscopic septotomy. Clinical success was 92.7 % for Z-POEM, 89.2 % for rigid septotomy, and 86.7 % for flexible septotomy (P = 0.26). Symptoms recurred in 24 patients (15 Z-POEM during a mean follow-up of 282.04 [SD 300.48] days, 6 flexible, 3 rigid [P = 0.47]). Adverse events occurred in 30.0 % rigid septotomy patients, 16.8 % Z-POEM patients, and 2.3 % flexible septotomy patients (P < 0.05). CONCLUSIONS: There was no difference in outcomes between the three treatment approaches for symptomatic Zenker's diverticulum. Rigid endoscopic septotomy was associated with the highest rate of complications, while flexible endoscopic septotomy appeared to be the safest. Recurrence following Z-POEM was similar to flexible and rigid endoscopic septotomy. Prospective studies with long-term follow-up are required.

Per Oral Endoscopic Myotomy for Zenker's Diverticulum: A Novel and Superior Technique Compared With Septotomy?

INTRODUCTION: Endoscopic management of Zenker diverticuli (ZD) has traditionally been via septotomy technique. The recent development of tunneling technique has shown to be both efficacious and safe. The aim of this study is to evaluate the tunneling technique using per oral endoscopic myotomy (Z-POEM) versus septotomy. METHODS: Patients who underwent endoscopic management of ZD either by Z-POEM or septotomy from March 2017 until November 2020 from 9 international academic centers were included. Demographics, clinical data preprocedure and postprocedure, procedure time, adverse events, and hospital length of stay were analyzed. RESULTS: A total of 101 patients (mean age 74.9 y old, 55.4% male) were included: septotomy (n=49), Z-POEM (n=52). Preprocedure Functional Oral Intake Scale score and Eckardt score was 5.3 and 5.4 for the septotomy group and 5.9 and 5.15 for the Z-POEM group. Technical success was achieved in 98% of the Z-POEM group and 100% of the septotomy group. Clinical success was achieved in 84% and 92% in the septotomy versus Z-POEM groups. Adverse events occurred in 30.6% (n=15) in septotomy group versus 9.6% (n=5) in the Z-POEM group (P=0.017). Reintervention for ongoing symptoms occurred in 7 patients in the septotomy group and 3 patients in the Z-POEM group. Mean hospital length of stay was shorter for the Z-POEM group, at 1.5 versus 1.9 days. CONCLUSIONS: A tunneling technique via the Z-POEM procedure is an efficacious and safe endoscopic treatment for ZD. Z-POEM is a safer procedure with a statistically significant reduction in adverse events compared with traditional septotomy technique.

Consensus guidelines on the role of cholangioscopy to diagnose indeterminate biliary stricture.

BACKGROUND: Indeterminate strictures pose a therapeutic dilemma. In recent years, cholangioscopy has evolved and the availability of cholangioscopy has increased. However, the position of cholangioscopy in the diagnostic algorithm to diagnose malignancy have not been well established. We aim to develop a consensus statement regarding the clinical role of cholangioscopy in the diagnosis of indeterminate biliary strictures. METHODS: The international experts reviewed the evidence and modified the statements using a three-step modified Delphi method. Each statement achieves consensus when it has at least 80% agreement. RESULTS: Nine final statements were formulated. An indeterminate biliary stricture is defined as that of uncertain etiology under imaging or tissue diagnosis. When available, cholangioscopic assessment and guided biopsy during the first round of ERCP may reduce the need to perform multiple procedures. Cholangioscopy are helpful in diagnosing malignant biliary strictures by both direct visualization and targeted biopsy. The absence of disease progression for at least 6 months is supportive of non-malignant etiology. Direct per-oral cholangioscopy provides the largest accessory channel, better image definition, with image enhancement but is technically demanding. Image enhancement during cholangioscopy may increase the diagnostic sensitivity of visual impression of malignant biliary strictures. Cholangioscopic imaging characteristics including tumor vessels, papillary projection, nodular or polypoid mass, and infiltrative lesions are highly suggestive for neoplastic/malignant biliary disease. The risk of cholangioscopy related cholangitis is higher than in standard ERCP, necessitating prophylactic antibiotics and ensuring adequate biliary drainage. Per-oral cholangioscopy may not be the modality of choice in the evaluation of distal biliary strictures due to inherent technical difficulties. CONCLUSION: Evidence supports that cholangioscopy has an adjunct role to abdominal imaging and ERCP tissue acquisition in order to evaluate and diagnose indeterminate biliary strictures.

Single-session endoscopic fundoplication after peroral endoscopic myotomy (POEM+F) for prevention of post gastroesophageal reflux - 1-year follow-up study.

BACKGROUND: Peroral endoscopic myotomy (POEM) is an established treatment for achalasia cardia; however, post-POEM gastroesophageal reflux (GER) remains a significant problem. Concomitant endoscopic fundoplication following POEM (POEM + F) was recently described to reduce post-POEM GER. This single-center study reports short-term outcomes of POEM + F. METHODS: This was a retrospective analysis of a prospectively maintained database of patients undergoing POEM + F. Abstracted data included demographics, achalasia type, pre-POEM Eckardt score, prior therapy, follow-up. Follow-up assessment was 3-monthly for 1 year and included post-POEM Eckardt score, GerdQ score, wrap integrity and esophagitis on esophagogastroduodenoscopy, and pH studies. GER was defined according to Lyon Consensus. RESULTS: 25 patients underwent POEM + F (mean age 40.1 years [standard deviation (SD) 13.7]; 12 females). POEM + F was technically successful in 23/25 (92.0 %). Significant dysphagia improvement was seen in all 25 patients (mean pre- and post-POEM Eckardt scores 8.21 [SD 1.08] and 0.1 [SD 0.3], respectively; P = 0.001). Mean total procedure and fundoplication times were 115.6 (SD 27.2) minutes and 46.7 (SD 12.4) minutes, respectively; times reduced significantly after the initial five cases. Median follow-up was 12 months (interquartile range [IQR] 9-13). Intact wrap was seen in 19/23 (82.6 %). GER (abnormal esophageal acid exposure time [EAET]) was seen in 2/18 (11.1 %) and there was one reported GerdQ > 8. Borderline GER (asymptomatic grade A esophagitis, normal EAET) was identified in 4/22 (18.2 %). Three (12.0 %) minor delayed adverse events occurred but required no intervention. CONCLUSIONS : POEM + F was safe and reproducible. At 12 months' follow-up, incidence of post-POEM + F GER was low and acceptable.

Initial experience with per-rectal endoscopic myotomy for Hirschsprung's disease: medium and long term outcomes of the first case series of a novel third-space endoscopy procedure.

INTRODUCTION: Hirschsprung's disease (HSCR) is congenital aganglionosis affecting the hindgut and presents with constipation. Surgical pull-through is the current standard treatment but causes morbidity. Per-rectal endoscopic myotomy is a novel third-space endoscopy technique for treating short-segment (SS)-HSCR. METHODS: Retrospective study of SS-HSCR patients diagnosed on history, contrast enema, rectal biopsies, and anorectal manometry, and treated by PREM. The aganglionic segment was mapped before PREM was performed using third-space endoscopy principles. Stool frequency and laxative usage before and after PREM were compared. RESULTS: Nine patients (age 7.5 [±â€Š5.2] years; 7 male) underwent PREM during a 4-year period. Mean aganglionic segment length was 6.3 cm, mean procedure time 96.1 minutes, and mean length of hospital stay 2.5 days. Median follow-up was 17 months (range 9-58 months). Stool frequency was 1/4.4 days before vs. 1/1.2 days after PREM (P = 0.0004). Mean laxative usage was 5.4 units of laxative (UL) before vs. 0.4 UL after PREM (P = 0.0002). No laxatives were used by 6/9 patients after PREM. The single adverse effect seen (anal stenosis) was treated with dilatation. CONCLUSIONS: PREM is a safe and effective minimally invasive procedure to treat SS-HSCR and results in long-term response.

Management of patients after failed peroral endoscopic myotomy: a multicenter study.

BACKGROUND: Although peroral endoscopic myotomy (POEM) is highly effective for the management of achalasia, clinical failures may occur. The optimal management of patients who fail POEM is not well known. This study aimed to compare the outcomes of different management strategies in patients who had failed POEM. METHODS: This was an international multicenter retrospective study at 16 tertiary centers between January 2012 and November 2019. All patients who underwent POEM and experienced persistent or recurrent symptoms (Eckardt score > 3) were included. The primary outcome was to compare the rates of clinical success (Eckardt score ≤ 3) between different management strategies. RESULTS : 99 patients (50 men [50.5 %]; mean age 51.4 [standard deviation (SD) 16.2]) experienced clinical failure during the study period, with a mean (SD) Eckardt score of 5.4 (0.3). A total of 29 patients (32.2 %) were managed conservatively and 70 (71 %) underwent retreatment (repeat POEM 33 [33 %], pneumatic dilation 30 [30 %], and laparoscopic Heller myotomy (LHM) 7 [7.1 %]). During a median follow-up of 10 (interquartile range 3 - 20) months, clinical success was highest in patients who underwent repeat POEM (25 /33 [76 %]; mean [SD] Eckardt score 2.1 [2.1]), followed by pneumatic dilation (18/30 [60 %]; Eckardt score 2.8 [2.3]), and LHM (2/7 [29 %]; Eckardt score 4 [1.8]; P = 0.12). A total of 11 patients in the conservative group (37.9 %; mean Eckardt score 4 [1.8]) achieved clinical success. CONCLUSION : This study comprehensively assessed an international cohort of patients who underwent management of failed POEM. Repeat POEM and pneumatic dilation achieved acceptable clinical success, with excellent safety profiles.

Use of a novel lumen apposing metallic stent for drainage of the bile duct and gallbladder: Long term outcomes of a prospective international trial.

BACKGROUND: Long-term placement of lumen apposing metal stents (LAMS) with high lumen apposing force may result in adverse events. The aim of the current study was to assess the long-term efficacy and safety of a self-approximating LAMS with lower lumen apposing force for endoscopic ultrasound-guided choledochoduodenostomy (EUS-CDS) and -gallbladder drainage (EUS-GBD). METHODS: Five Asian institutions participated in this study. Consecutive patients suffering from obstructive jaundice with failed ERCP or acute cholecystitis that were at high risk for cholecystectomy were recruited. We evaluated the technical and clinical success rates, adverse events rates, types of interventions through the stent and the patency profile. RESULTS: From June 2017 to Oct 2018, a total of 53 patients received EUS-CDS (26) and EUS-GBD (27). The technical and clinical success rates were similar between the two groups (88.5% vs 88.9%, P = 1 and 88.5% vs 88.9%, P = 1 respectively). The differences in 30-day mortality rates [2 (7.7%) vs 2 (7.7%), P = 1] and adverse events [3 (11.5%) vs 3 (11.5%), P = 1] did not reach significance. Regarding long-term outcomes, two patients in each group suffered from adverse events (P = 1). One patient in the EUS-GBD group who was on direct oral anticoagulant suffered from stent induced bleeding. CONCLUSION: The self-approximating LAMS with lower lumen apposing force was effective and safe with a low risk of buried stent syndrome and bleeding in the longer term. The ClinicalTrials.gov Identifier was NCT03002051.

Third Space Endoscopy: Lessons Learnt From a Decade of Submucosal Endoscopy.

The field of third space endoscopy (TSE), also called submucosal endoscopy using a mucosal flap valve, allows secure access to the submucosal and deeper layers of the gastrointestinal tract without the risk of a full-thickness perforation. Since the first description of per-oral endoscopic myotomy (POEM) for the treatment of achalasia cardia 10 years ago, this field has expanded rapidly. Several new procedures, submucosal tunneling endoscopic resection, gastric-POEM, Zenker POEM, per-rectal endoscopic myotomy, diverticular POEM, and recanalization for complete esophageal obstruction (per-oral endoscopic tunneling for restoration of the esophagus), have been performed. All TSE procedures employ a similar technique-after a mucosal incision, a submucosal tunnel is created, a myotomy is performed, or a subepithelial tumor is resected distal to the site of mucosal incision, after which the mucosal incision is closed. Potential indications for TSE include resection of subepithelial tumors in the esophagus, gastroesophageal junction, or stomach; refractory gastroparesis; Zenker diverticulum; Hirschsprung disease or other forms of megacolon; and recanalization for complete esophageal obstruction. Data are currently available for POEM, submucosal tunneling endoscopic resection, and gastric-POEM, although mainly in the form of retrospective studies, and randomized trials and long-term follow-up data are limited. Submucosal endoscopy has an excellent safety profile with very few intraoperative adverse events, the majority being related to insufflation, although bleeding, perforation, and sepsis have been reported. TSE procedures require special training and have demonstrated a learning curve.

Prospective multicenter international study on the outcomes of a newly developed self-approximating lumen-apposing metallic stent for drainage of pancreatic fluid collections and endoscopic necrosectomy.

BACKGROUND: A novel self-approximating lumen-apposing metallic stent (LAMS; Niti-S Spaxus, Taewoong Medical, Gyeonggi-do, Korea) has recently become available. The aim of the present study was to evaluate the outcomes for drainage of pancreatic fluid collections (PFC). METHODS: This was a prospective international multicentered study conducted in six high-volume institutions across Asia. Consecutive patients suffering from pancreatic pseudocyst or walled-off pancreatic necrosis (WOPN) requiring endoscopic ultrasonography-guided drainage were recruited. Outcomes included technical and clinical success, adverse events, procedural events, interventions through the stent and recurrence rates. RESULTS: Between August 2016 and November 2017, 59 patients were recruited to this study. Thirty-nine patients (66.1%) had WOPN and mean (SD) size of PFC was 11.5 (5.1) cm. Technical and clinical success rates were 100%. Mean (SD) procedural time was 35.0 (17.2) minutes. Sixteen-millimeter stents were used in 66.1% of the patients. Fifty-four sessions of necrosectomy were carried out with the stent in situ in 17 patients. Stent-related adverse event (AE) rate was 6.8%. Three patients (5.1%) suffered from bleeding after stenting and one required angiographic embolization. Two patients (3.4%) suffered from recurrence during a mean (SD) follow-up time of 325.6 (355.5) days. There were no differences in outcomes between those with pseudocysts or WOPN except for the duration of hospital stay (P = 0.012). CONCLUSION: Use of a self-approximating LAMS for drainage of PFC was safe and effective. Endoscopic necrosectomy could be carried out through the stent with ease. The device was associated with a low rate of stent-related AE.

Retraction notice to "Long-term outcomes of per-oral endoscopic myotomy in patients with achalasia with a minimum follow-up of 2 years: an international multicenter study": [YMGE 85 (2017) 927-933].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted due to overlapping/duplicate material. Data from some patients from this study have previously been published in other journals without cross-referencing. Twenty patients overlap with a paper by Kumbhari et al.1 Thirty-five patients overlap with the study by Ngamruengphong et al.2.

Management of achalasia cardia: Expert consensus statements.

Achalasia cardia (AC) is a frequently encountered motility disorder of the esophagus resulting from an irreversible degeneration of neurons. Treatment modalities are palliative in nature, and there is no curative treatment available for AC as of now. Significant advancements have been made in the management of AC over last decade. The introduction of high resolution manometry and per-oral endoscopic myotomy (POEM) has strengthened the diagnostic and therapeutic armamentarium of AC. High resolution manometry allows for the characterization of the type of achalasia, which in turn has important therapeutic implications. The endoscopic management of AC has been reinforced with the introduction of POEM that has been found to be highly effective and safe in palliating the symptoms in short-term to mid-term follow-up studies. POEM is less invasive than Heller's myotomy and provides the endoscopist with the opportunity of adjusting the length and orientation of esophageal myotomy according to the type of AC. The management of achalasia needs to be tailored for each patient, and the role of pneumatic balloon dilatation, POEM, or Heller's myotomy needs to be revisited. In this review, we discuss the important aspects of diagnosis as well as management of AC. The statements presented in the manuscript reflect the cumulative efforts of an expert consensus group.

Efficacy and Safety of Peroral Endoscopic Myotomy for Treatment of Achalasia After Failed Heller Myotomy.

BACKGROUND & AIMS: In patients with persistent symptoms after Heller myotomy (HM), treatment options include repeat HM, pneumatic dilation, or peroral endoscopic myotomy (POEM). We evaluated the efficacy and safety of POEM in patients with achalasia with prior HM vs without prior HM. METHODS: We conducted a retrospective cohort study of 180 patients with achalasia who underwent POEM at 13 tertiary centers worldwide, from December 2009 through September 2015. Patients were divided into 2 groups: those with prior HM (HM group, exposure; n = 90) and those without prior HM (non-HM group; n = 90). Clinical response was defined by a decrease in Eckardt scores to 3 or less. Adverse events were graded according to criteria set by the American Society for Gastrointestinal Endoscopy. Technical success, clinical success, and rates of adverse events were compared between groups. Patients were followed up for a median of 8.5 months. RESULTS: POEM was technically successful in 98% of patients in the HM group and in 100% of patients in the non-HM group (P = .49). A significantly lower proportion of patients in the HM group had a clinical response to POEM (81%) than in the non-HM group (94%; P = .01). There were no significant differences in rates of adverse events between the groups (8% in the HM group vs 13% in the non-HM group; P = .23). Symptomatic reflux and reflux esophagitis after POEM were comparable between groups. CONCLUSIONS: POEM is safe and effective for patients with achalasia who were not treated successfully by prior HM. Although the rate of clinical success in patients with prior HM is lower than in those without prior HM, the safety profile of POEM is comparable between groups.