Self-expandable Metallic Stent Placement Research Articles

Management of Malignant Gastric Outlet Obstruction: A Comprehensive Review on the Old, the Classic and the Innovative Approaches.

Gastrojejunostomy is the principal method of palliation for unresectable malignant gastric outlet obstructions (GOO). Gastrojejunostomy was traditionally performed as a surgical procedure with an open approach butrecently, notable progress in the development of minimally invasive procedures such as laparoscopic gastrojejunostomies have emerged. Additionally, advancements in endoscopic techniques, including endoscopic stenting (ES) and endoscopic ultrasound-guided gastroenterostomy (EUS-GE), are becoming more prominent. ES involves the placement of self-expandable metal stents (SEMS) to restore luminal patency. ES is commonly the first choice for patients deemed unfit for surgery or at high surgical risk. However, although ES leads to rapid improvement of symptoms, it carries limitations like higher stent dysfunction rates and the need for frequent re-interventions. Recently, EUS-GE has emerged as a potential alternative, combining the minimally invasive nature of the endoscopic approach with the long-lasting effects of a gastrojejunostomy. Having reviewed the advantages and disadvantages of these different techniques, this article aims to provide a comprehensive review regarding the management of unresectable malignant GOO.

Oncologic investigation of the interval from stent placement to surgery in patients with obstructive colorectal cancer.

Self-expandable metallic stent (SEMS) placement is widely used as a bridge to surgery (BTS) procedure for obstructive colorectal cancer. However, evidence regarding the optimal interval between SEMS placement and elective surgery is lacking. We retrospectively collected data from patients with BTS between January 2013 and October 2021. Inverse probability treatment-weighted propensity score analyses were used to compare short- and long-term outcomes between the short-interval (SI) and long-interval (LI) groups, using a cutoff of 20days. In total, 138 patients were enrolled in this study (SI group, n = 63; LI group, n = 75). In the matched cohort, the patients' backgrounds were well balanced. The incidence of Clavien-Dindo grade ≥ II postoperative complications was not significantly different between the SI and LI groups (19.0% vs. 14.0%, P = 0.47). There were no significant differences between the SI and LI groups in the 3-year recurrence-free survival (68.0% vs. 76.4%, P = 0.73) or 3-year overall survival rates (86.0% vs. 90.6%, P = 0.72). A longer interval did not deteriorate the oncological outcomes. Individual perioperative management with an appropriate interval to improve the patient's condition is required to ensure safe surgery.

First experience of endoscopic radiofrequency ablation in tumor-induced stenosis of extrahepatic bile ducts

Aim. To evaluate technical features, safety and efficiency of radiofrequency ablation in tumor strictures of extrahepatic bile ducts. Materials and methods. An ongoing prospective observational study from September 2022 to June 2023 enrolled patients with unresectable extrahepatic bile duct tumors. Examination involved esophagogastroduodenoscopy, endoscopic ultrasound, retrograde cholangiopancreatography and video choledochoscopy with biopsy. Ductalradiofrequency ablation with polymeric or self-expanding metallic stent placement was applied as the main treatment method for the first time in Russia. Results. 3 patients (75 %) were diagnosed with cholangiocarcinoma of stage IIb–IIIa, 1 patient – with mucinous cystic tumor with signs of severe intraepithelial neoplasia. Radiofrequency ablation was successfully performed in all patients: tumor stenosis was completely eliminated, no complications reported in the immediate and distant period. The median follow-up period amounted to 8 months. Conclusion. The results of the first application of ductal radiofrequency ablation in unresectable tumors of extrahepatic bile ducts with stenosis prove to be positive. The method is considered to be effective, minimally invasive and safe.

Impact of the Supra-papilla Method on Patency in Distal Malignant Biliary Obstruction: A Multicenter Randomized Controlled Trial

/aims: Placement of a self-expandable metal stent (SEMS) across the duodenal major papilla carries a risk of duodenobiliary reflux (DBR). The supra-papilla method of stenting may reduce DBR and improve stent patency compared to the trans-papilla method. This study aimed to compare the clinical outcomes between the supra-papilla and trans-papilla methods for distal malignant biliary obstruction (DMBO). Between January 2021 and January 2023, consecutive patients with DMBO from six centers in Korea were randomly assigned to either the supra-papilla or trans-papilla method arm in a 1:1 ratio. The primary outcome was the duration of stent patency, and secondary outcomes included the cause of stent dysfunction, adverse events, and overall survival rate. A total of 84 patients were equally assigned to each group. The most common cause of DMBO was pancreatic cancer (n=50, 59.5%), followed by bile duct (n=20, 23.8%), gallbladder (n=11, 13.1%), and other cancers (n=3, 3.6%). Stent patency was significantly longer in the supra-papilla group (median [95% confidence interval], 369 [289-497] vs. 154 [78-361] days; P < 0.01). Development of DBR was significantly lower in the supra-papilla group (9.4% vs 40.8%, P < 0.01). Adverse events and overall survival rate were not significantly different between the two groups. The placement of SEMS using the supra-papilla method resulted in a significantly longer duration of stent patency. It is advisable to place the SEMS using the supra-papilla method in DMBO. Further studies with a larger number of patients are required to validate the benefits of the supra-papilla method.

Risk factors and treatment strategies for cholecystitis after metallic stent placement for malignant biliary obstruction: a multicenter retrospective study

Background and study aimsCholecystitis can occur after self-expandable metallic stent (SEMS) placement for malignant biliary obstructions (MBO). Furthermore, the best treatment option for cholecystitis has not been determined. Here, we aimed to identify the risk factors of cholecystitis after SEMS placement and determine the best treatment option. Patients and MethodsIncidence, treatments, and predictive factors of cholecystitis were retrospectively evaluated in 1,084 patients with distal MBO (DMBO) and 353 patients with hilar MBO (HMBO) who underwent SEMS placement at the 12 institutions from January 2012 to March 2021. ResultsCholecystitis occurred in 7.5% of patients with DMBO and 5.9% of patients with HMBO. The recurrence rate was significantly lower (p=0.043), and the recurrence-free period was significantly longer (p=0.039) in endoscopic procedures than in percutaneous procedures for cholecystitis treatment. Endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) was better in terms of technical success, procedure time, and recurrence-free period than endoscopic transpapillary gallbladder drainage. The cases with obstruction across the cystic duct orifice by tumor (p=0.015) and those with obstruction by stent (p=0.037) were the independent risk factors for cholecystitis in DMBO. The cases with multiple SEMS placements (OR 11, 95% CI 0.68–190, p=0.091) and those with gallbladder stones (OR 2.3, 95% CI 0.92–5.6, p=0.075) had a higher risk for cholecystitis in HMBO. ConclusionsThe incidences of cholecystitis after SEMS placement for DMBO and HMBO were comparable. EUS-GBD is the optimal treatment option for patients with cholecystitis after SEMS placement for MBO.

Efficacy and Safety Analysis of Emergency Endoscopic Self-Expanding Metal Stent Placement Without Fluoroscopic Assistance for Right-Sided Colonic Cancer Obstruction.

Traditionally, surgical treatment is recommended for right-sided colonic cancer obstruction (RCCO); however, the literature comparing surgical or non-surgical procedures is lacking. Patients included in this study were divided into two groups: one group received elective surgery after self-expanding metal stent (SEMS) placement, i.e., the bridge to surgery (BTS) group, and one group received emergency surgery (ES). Thirty-five patients were included in the BTS group and 60 patients underwent ES. The technical and clinical success rates for SEMS placement were 100% and 88.6%, respectively, while the short-term complication rates were 51.4% and 33.3% for the BTS and ES groups, respectively (p=0.082). Overall, 2.9% and 3.3% of postoperative deaths occurred in the BTS and ES groups (p=1.000). The 1-year overall survival (OS) rates were 91.4% and 88.3% (p=0.840), 3-year OS rates were 85.7% and 81.7% (p=0.860), and 5-year OS rates were 82.9% and 76.7% (p=0.620) in the BTS and ES groups, respectively. No tumor recurrence was found in the BTS group but seven recurrences were found in the ES group (11.7%) [p=0.091]. Laparoscopic surgery was chosen by 42.9% of patients in the BTS group and 26.7% of patients in the ES group (p=0.104); however, the length of hospital stay (p=0.001) was longer in the BTS group. In the two groups, no differences were found in terms of postoperative complications and mortality as well as OS. The BTS group preferred to perform laparoscopic surgery and the technical success rate of stenting was high, therefore SEMS for RCCO was considered safe and feasible.

Revealing Insights: A Comprehensive Overview of Gastric Outlet Obstruction Management, with Special Emphasis on EUS-Guided Gastroenterostomy.

Gastric outlet obstruction (GOO) poses a common and challenging clinical scenario, characterized by mechanical blockage in the pylorus, distal stomach, or duodenum, resulting in symptoms such as nausea, vomiting, abdominal pain, and early satiety. Its diverse etiology encompasses both benign and malignant disorders. The spectrum of current treatment modalities extends from conservative approaches to more invasive interventions, incorporating procedures like surgical gastroenterostomy (SGE), self-expandable metallic stents (SEMSs) placement, and the advanced technique of endoscopic ultrasound-guided gastroenterostomy (EUS-GE). While surgery is favored for longer life expectancy, stents are preferred in malignant gastric outlet stenosis. The novel EUS-GE technique, employing a lumen-apposing self-expandable metal stent (LAMS), combines the immediate efficacy of stents with the enduring benefits of gastroenterostomy. Despite its promising outcomes, EUS-GE is a technically demanding procedure requiring specialized expertise and facilities.

Traumatic esophageal fistula secondary to self-expandable metal stent placement

Traumatic esophageal fistula secondary to self-expandable metal stent placement

Relief of Obstruction in Left-Sided Obstructive Colon Cancer: Nationwide Analysis of Applied Treatment in the Palliative Setting

Relief of Obstruction in Left-Sided Obstructive Colon Cancer: Nationwide Analysis of Applied Treatment in the Palliative Setting

Pancreatic Pseudocyst after Fully Covered Self-expandable Metallic Stent Placement: A Case Report.

A 70-year-old woman presented with stage III pancreatic head cancer. After endoscopic sphincterotomy, a fully covered self-expandable metallic stent (FCSEMS) was placed in the common bile duct to manage jaundice. The patient developed a fever and abdominal pain 40 days after stent placement, with a suspected diagnosis of infected pancreatic pseudocyst. Purulent discharge from the papilla was observed during FCSEMS removal, and pancreatography revealed a pseudocyst connected to the main pancreatic duct. The pancreatic pseudocyst resolved after transpapillary drainage. Pancreatic pseudocysts should be suspected after biliary FCSEMS placement, and prompt removal and endoscopic drainage of the FCSEMS should be considered.

Factors associated with patency of self-expandable metal stents in malignant biliary obstruction

IntroductionEndoscopic self-expandable metal stent (SEMS) placement is the key endoscopic treatment for unresectable malignant biliary obstruction. The benefit of covered SEMS over uncovered SEMS remains unknown as are risk factors for SEMS dysfunction. This study aimed to determine the factors associated with patency of SEMS.MethodsPatients with unresectable malignant biliary obstruction who underwent endoscopic SEMS placement at Ramathibodi Hospital, during January 2012 to March 2021 were included. Patient characteristics, clinical outcomes and patency of SEMS were collected. The primary outcome were stent patency and factors associated with patency of SEMS. The factors were analyzed by univariate and multivariate analyses. Median days of stent patency, median time of patient survival, rate of reintervention and complications after SEMS placement were collected.ResultsOne hundred and fourteen patients were included. SEMS dysfunction was found in 37 patients (32.5%). Size of cancer (Hazard ratio (HR), 1.20, (95% CI 1.02, 1.40), p 0.025), presence of stones or sludge during SEMS placement (Hazard ratio (HR), 3.91, (95% CI 1.74, 8.75), p 0.001), length of SEMS, 8 cm (HR 2.96, (95% CI 1.06, 8.3), p 0.039), and total bilirubin level above 2 mg/dL at one month after SEMS placement (HR 1.14, (95% CI 1.06, 1.22), p < 0.001) were associated with SEMS dysfunction. The median stent patency was 97 days. The median patient survival was 133 days, (95% CI 75–165). The rate of reintervention was 86% in patients with SEMS dysfunction.ConclusionThe size of cancer, presence of stones or sludge during SEMS placement, the length of SEMS, and total bilirubin level above 2 mg/dL at 1 month after SEMS placement were associated with SEMS dysfunction. The median time of stent patency were not statistically different in each type of stent, covered stent, partially covered stent and uncovered stent. Median survival time of patients did not associate with SEMS patency or dysfunction.

Preoperative endoscopic biliary drainage by metal versus plastic stents for resectable perihilar cholangiocarcinoma

Background and study aimsAdequate preoperative biliary drainage (PBD) is recommended in most patients with resectable perihilar cholangiocarcinoma (pCCA). Most expert centers use endoscopic plastic stents rather than self-expanding metal stents (SEMS). In the palliative setting, however, use of SEMS has shown longer patency and superior survival. The aim of this retrospective study was to compare stent dysfunction of SEMS versus plastic stents for PBD in resectable pCCA patients. Patients and methodsIn this retrospective, multicenter, international cohort study, patients with a potentially resectable pCCA who underwent initial endoscopic PBD were included from 2010-2020. Stent failure was a composite endpoint of cholangitis and/or re-intervention due to adverse events or insufficient PBD. Other adverse events, surgical outcomes, and survival were recorded. Propensity score matching (PSM) was performed on several baseline characteristics. Results474 patients had successful stent placement, of whom 61 received SEMS and 413 plastic stents. PSM (1:1) resulted in two groups of 59 patients. Stent failure occurred significantly less in the SEMS group (31% vs 64%, p<0.001). Besides less cholangitis after SEMS placement (15% vs 31%, p = 0.012), other PBD-related adverse events did not differ. The number of patients undergoing surgical resection was not significantly different (46% vs 49%, p = 0.71). Complete intraoperative SEMS removal was successful and without adverse events in all patients. ConclusionsStent failure was lower in patients with SEMS as PBD compared to plastic stents in patients with resectable pCCA. Removal during surgery was well feasible. Surgical outcomes were comparable.

Usefulness of Intraductal Placement of a Dumbbell-Shaped Fully Covered Self-Expandable Metal Stent for Post-Cholecystectomy Bile Leaks.

Background and aims: In the treatment of post-cholecystectomy bile leaks, endoscopic naso-biliary drainage (ENBD) or biliary stenting using plastic stents is the standard of care. Fully covered self-expandable metal stent (FCSEMS) placement across the sphincter of Oddi is considered a salvage therapy for refractory cases, but pancreatitis and migration are the major concerns. Intraductal placement of a dumbbell-shaped FCSEMS (D-SEMS) could avoid these drawbacks of FCMSESs. In this retrospective study, we investigated the usefulness of intraductal placement of the D-SEMS for post-cholecystectomy bile leaks. Methods: Six patients who underwent intraductal placement of the D-SEMS for post-cholecystectomy bile leaks were enrolled. This method was performed as initial treatment in three patients and as salvage treatment in three ENBD refractory cases. Results: Technical and clinical successes were obtained in 6 (100%) patients and 5 (83%) patients, respectively. One clinically unsuccessful patient required laparoscopic peritoneal lavage. The early adverse event was one case of mild pancreatitis (17%). The median duration of the D-SEMS indwelling was 61 days (42-606 days) with no migration cases, all of which were successfully removed. The median follow-up after index ERCP was 761 (range: 161-1392) days with no cases of recurrent bile leaks. Conclusions: Intraductal placement of the D-SEMS for post-cholecystectomy bile leaks might be safe and effective even in refractory cases.

Endoscopic Ultrasound-Guided Naso-gallbladder Drainage Using a Dedicated Catheter for Acute Cholecystitis After Transpapillary Metal Stent Placement for Malignant Biliary Obstruction.

Acute cholecystitis is a significant adverse event after self-expandable metal stent (SEMS) placement for malignant biliary obstruction (MBO); however, no appropriate treatment strategy has been established for its management. This study aimed to examine the feasibility and utility of endoscopic ultrasound-guided naso-gallbladder drainage (EUS-NGBD) for the management of acute cholecystitis occurring after SEMS placement. This retrospective study investigated consecutive patients with acute cholecystitis after SEMS placement for unresectable MBO, in whom EUS-NGBD was attempted. The study outcomes included technical success, clinical success, procedure time, adverse event, and cholecystitis recurrence, associated with the procedure. During the study period, EUS-NGBD was performed for SEMS-related acute cholecystitis in 30 patients with MBO. The technical and clinical success rates were 96.7% (29/30) and 96.6% (28/29), respectively. The median procedure time was 15min, and rate of procedure-related adverse event was 3.3% (1/30). The median duration from the procedure to tube removal was 9days. No adverse events were observed after removal. The median hospitalization duration after the procedure was 14days, and the median duration to the (re-)start of chemotherapy from cholecystitis onset was 13days. The median overall survival after EUS-NGBD was 123days, and the rate of cholecystitis recurrence until death was 4.2% (1/28). This study demonstrated that EUS-NGBD possesses good technical and clinical feasibility with an acceptable adverse event rates and short hospitalization and chemotherapy withdrawal period. Therefore, EUS-NGBD may be a good option for the treatment of SEMS-related cholecystitis in patients with MBO.

The evaluation of bilateral stenting using braided or laser-cut self-expandable metallic stent for malignant hilar biliary obstruction.

Bilateral self-expandable metallic stent (SEMS) placement for unresectable malignant hilar biliary obstruction (UMHBO) is an effective option for biliary drainage with long-term stent patency. Laser-cut and braided SEMS can be used for bilateral SEMS placement. This study aimed to clarify any differences in the clinical features and proper use of the laser-cut and braided SEMS placement using the stent-in-stent method for UMHBO. In this study, 78 patients who underwent bilateral stent-in-stent SEMS placement for UMHBO were included. The patients were divided into the laser-cut (n = 33) and braided groups (n = 45). Both groups were compared for technical and clinical success, adverse events (AEs), time to recurrent biliary obstruction (TRBO), overall survival, and endoscopic reintervention (ERI). There were no significant differences in technical and clinical success rates (laser-cut vs. braided group, 97% vs. 95.6%, P = 1.0), AEs (21.2% vs. 15.6%. P = 0.56), median TRBO (242days vs. 140days, P = 0.36), and median overall survival (654days vs. 675days, P = 0.58). ERI was required in 15 patients in the laser-cut group and in 20 patients in the braided group. The technical and clinical success rates of ERI (60% vs. 85%) were not significantly different (P = 0.13); however, the median ERI procedure time was significantly longer in the laser-cut group (38min) than in the braided group (22min; P = 0.02). No significant difference in initial SEMS placement was noted between the laser-cut and braided groups; however, the laser-cut group required a longer ERI procedure time than that required by the braided group. The use of braided SEMS may be a convenient option for ERI.

Risk factors for early and late cholecystitis after covered metal stent placement for distal biliary obstruction.

Cholecystitis is a major adverse event after self-expandable metallic stent placement for distal biliary obstruction (DBO). Covered self-expandable metallic stent (CSEMS) is being increasingly used, but few studies have investigated risk factors for cholecystitis limited to CSEMS. The present study aimed to identify risk factors for cholecystitis after CSEMS. Patients who underwent initial CSEMS placement for DBO between November 2014 and September 2021 were enrolled and followed-up until death, recurrent biliary obstruction, cholecystitis, or until March 2022. Cholecystitis within 30 days of CSEMS was defined as early cholecystitis and after 30 days as late cholecystitis. Cholecystitis occurred in 51 of 339 patients (15%) after CSEMS. Forty-one patients (80.4%) had early cholecystitis, and 10 (19.6%) had late cholecystitis. Multivariate logistic regression analysis revealed that the maximum diameter of the common bile duct (CBD) (per 1 mm increase) (odds ratio [OR]: 0.87; 95% confidence interval [CI]: 0.76-1.00; p = .044), gallbladder stones (OR: 3.63; 95% CI: 1.62-8.10; p = .002), and tumor involvement in the cystic duct (CD) (OR: 4.87; 95% CI: 2.16-11.00; p < .001) were significant independent risk factors associated with early cholecystitis. No significant risk factors were identified for late cholecystitis. A smaller CBD diameter, gallbladder stones, and tumor involvement in the CD were identified as risk factors for early cholecystitis development after CSEMS.

Endoscopic ultrasound-guided drainage of perforated gallbladder in patients with hilar cholangiocarcinoma postbiliary uncovered self-expandable metal stent placement.

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Efficacy and Safety of Self-Expandable Metallic Stent Placement for Malignant Esophageal Fistula.

Patients with malignant esophageal fistulas often experience dysphagia and infection, resulting in poor prognoses. Self-expandable metallic stent (SEMS) placement is a palliative treatment option; however, its efficacy and safety are unclear. We aimed to determine the efficacy and safety of SEMS placement for malignant esophageal fistulas. We retrospectively investigated patients who underwent SEMS placement for malignant esophageal fistulas between 2013 and 2022 at the Cancer Institute Hospital. Dysphagia scores (DSs) before and after SEMS placement, adverse events, and overall survival from SEMS placement until death were evaluated. A total of 17 patients underwent SEMS placement, including 12 and 5 patients with esophageal and lung cancers, respectively. Prior treatments included chemoradiotherapy (n = 11), radiotherapy (n = 4), and chemotherapy (n = 4); two patients underwent palliative radiotherapy after chemotherapy. All procedures were technically successful. After SEMS placement, 14 (82.4%) patients were able to consume semisolid or solid food (DS ≤ 2). Major adverse events were encountered in only one case. The median survival time after SEMS placement was 71 days (range 17-247 days). SEMS placement allowed most patients to resume oral intake with a low rate of major adverse events. SEMS placement is a reasonable palliative treatment option for patients with malignant fistulas who have poor prognoses.

Radiofrequency ablation via an implanted self-expandable metallic stent to treat in-stent restenosis in a rat gastric outlet obstruction model.

Background: In-stent restenosis caused by tissue hyperplasia and tumor growth through the wire meshes of an implanted self-expandable metallic stent (SEMS) remains an unresolved obstacle. This study aimed to investigate the safety and efficacy of SEMS-mediated radiofrequency ablation (RFA) for treating stent-induced tissue hyperplasia in a rat gastric outlet obstruction model. Methods: The ablation zone was investigated using extracted porcine liver according to the ablation time. The optimal RFA parameters were evaluated in the dissected rat gastric outlet. We allocated 40 male rats to four groups of 10 rats as follows: group A, SEMS placement only; group B, SEMS-mediated RFA at 4 weeks; group C, SEMS-mediated RFA at 4 weeks and housed until 8 weeks; and group D, SEMS-mediated RFA at 4 and 8 weeks. Endoscopy and fluoroscopy for in vivo imaging and histological and immunohistochemical analysis were performed to compare experimental groups. Results: Stent placement and SEMS-mediated RFA with an optimized RFA parameter were technically successful in all groups. Granulation tissue formation-related variables were significantly higher in group A than in groups B-D (all p < 0.05). Endoscopic and histological findings confirmed that the degrees of stent-induced tissue hyperplasia in group D were significantly lower than in groups B and C (all p < 0.05). Hsp70 and TUNEL expressions were significantly higher in groups B-D than in group A (all p < 0.001). Conclusion: The implanted SEMS-mediated RFA successfully managed stent-induced tissue hyperplasia, and repeated or periodic RFA seems to be more effective in treating in-stent restenosis in a rat gastric outlet obstruction model.

EUS-guided Gastroenterostomy: A Multicenter International Study Comparing Benign and Malignant Diseases.

Endoscopic ultrasound (EUS)-guided gastroenterostomy (EUS-GE) is a minimally invasive therapy for patients with gastric outlet obstruction without the risks of surgical bypass and the limited long-term efficacy of enteral self-expanding metal stent placement. However, due to its novelty, there is a lack of significant data comparing long-term outcomes of patients with EUS-GE, based on the underlying disease. In this study, we compare outcomes of EUS-GE on benign versus malignant indications. Consecutive patients from 12 international, tertiary care centers who underwent EUS-GE over 3 years were extracted in a retrospective registry. Demographic characteristics, procedure-related information and follow-up data was collected. Primary outcome was the rate of adverse events associated with EUS-GE and the comparison of the rate of adverse events in benign versus malignant diseases. Secondary outcomes included technical and clinical success as well as hospitalization admission. A total of 103 patients were included: 72 malignant and 31 benign. The characteristics of the patients undergoing EUS-GE is shown in Table 1. The mean age of the cohort was 68 years and 58 years for malignant and benign etiology. Gender distribution was 57% and 39% being females in malignant and benign etiology group, respectively. Clinical success, technical success, average procedure time, and hospital length of stay were similar in both groups. Patients with benign underlying etiology had significantly higher number of surgically altered midgut anatomy (P=0.0379). EUS-GE is equally efficient regardless of the underlying etiology (malignant vs. benign), and the adverse events both groups were comparable.