Biography:

In the past Alan N. Barkun has collaborated on articles with Elham Rahme and Jacques Devière. One of their most recent publications is Physicochemical determinants of in vitro shock-wave biliary lithotripsy***. Which was published in journal Gastroenterology.

More information about Alan N. Barkun research including statistics on their citations can be found on their Copernicus Academic profile page.

Alan N. Barkun's Articles: (13)

Physicochemical determinants of in vitro shock-wave biliary lithotripsy***

AbstractHuman gallstones were studied by visual inspection, computerized tomographic imaging, and chemical analysis to assess physicochemical characteristics that may determine the outcome of in vitro shock-wave fragmentation. Eighty-five stones (mean diameter: 13.2 ± 5 mm) were each collected from different patients. Fifty-five (65%) calculi were angular and 30 (35%) round or oval-shaped. Three easily obtained measures were derived from each stone's optimal computerized tomographic image including the mean stone density, a measure corresponding to the standard deviation of the mean stone density value which we termed the stone density distribution index and which may reflect the physicochemical heterogeneity of a given gallstone, as well as the density range. After the administration of 2500 shock waves using an electrohydraulic generator, fragmentation was noted in 68 calculi (80%) and was satisfactory in 27 (32%) (where the largest resulting fragment diameters were all ≤5 mm). Strong determinants of satisfactory fragmentation on multivariate analysis included a stone diameter of ≤15 mm, the presence of an angular stone shape, and a stone density distribution index of ≥60 Hounsfield units. The other parameters did not independently determine satisfactory fragmentation. Prospective clinical trials are needed to assess whether these findings result in a better prediction of the success of extracorporeal biliary lithotripsy and a broadening of its indications.

Clinical studySplenic enlargement and Traube's space: How useful is percussion?*

PurposeThe utility of Traube's space percussion in the bedside assessment of splenic enlargement was evaluated. The influence of meals and obesity on this sign were also assessed, because both are believed to interfere with the results of abdominal percussion.Patients and methodsThe inpatient population of a tertiary care hospital was studied where cases and controls were selected according to the results of abdominal ultrasonographic examinations.ResultsTraube's space percussion exhibited a sensitivity of 0.62 (95% confidence interval [CI], 0.51 to 0.71) and a specificity of 0.72 (95% CI, 0.65 to 0.80) when classifying tympanitic examinations as negative. False-positive examinations were reduced by assessing patients more than two hours after mealtime. Obese patients were a source of falsenegative examinations.ConclusionTraube's space percussion compares favorably with other commonly used clinical maneuvers and diagnostic tests. When performed alone in a selected patient population, it adds useful clinical information but is not sufficiently sensitive or specific to obviate the need for further diagnostic testing.

Clinical-alimentary tractThe cyclooxygenase-2-selective inhibitors rofecoxib and celecoxib prevent colorectal neoplasia occurrence and recurrence☆

AbstractBackground & Aims:Colorectal cancer is one of the leading causes of cancer death. Most colorectal cancers are believed to develop from colorectal adenomas. We examined the effect of the selective cyclooxygenase-2 inhibitors rofecoxib and celecoxib, nonselective nonsteroidal anti-inflammatory drugs, aspirin, and acetaminophen on colorectal neoplasia (colorectal cancer, colorectal adenoma, or both).Methods:This was a nested case-control study, which used data from a government insurance database on patients 65 years and older who underwent a diagnostic test or procedure for colorectal neoplasia between January and June 2001. Logistic regression models were used to determine the effect of exposure to the drugs of interest for at least 3 months on the occurrence or recurrence of colorectal neoplasia.Results:The control group included 2568 patients found to be free of colorectal neoplasia; 730 patients were diagnosed with colorectal adenoma, and 179 were diagnosed with colorectal cancer. Patients more likely to have colorectal adenoma (odds ratio, 95% confidence interval) were those diagnosed with colorectal adenoma (4.12, 3.27–5.18) or colorectal cancer (3.74, 2.32–6.03) in the previous 1–3 years and those with hemorrhage of the rectum or unspecified anemia in the prior month (3.19, 2.46–4.12). Exposures to rofecoxib (0.67, 0.46–0.98) and nonselective nonsteroidal anti-inflammatory drugs (0.41, 0.21–0.83) reduced the risk of colorectal adenoma. Rofecoxib, celecoxib, and nonselective nonsteroidal anti-inflammatory drugs were all protective against both neoplasias (0.64, 0.45–0.91; 0.73, 0.54–0.99; and 0.47, 0.26–0.86, respectively).Conclusions:Rofecoxib, celecoxib, and nonselective nonsteroidal anti-inflammatory drugs seem to protect against the development of colorectal neoplasia.

Original ResearchFull Report: Clinical—BiliarySuccessful Management of Benign Biliary Strictures With Fully Covered Self-Expanding Metal Stents

Background & AimsFully covered self-expanding metal stents (FCSEMS) are gaining acceptance for the treatment of benign biliary strictures. We performed a large prospective multinational study to study the ability to remove these stents after extended indwell and the frequency and durability of stricture resolution.MethodsIn a nonrandomized study at 13 centers in 11 countries, 187 patients with benign biliary strictures received FCSEMS. Removal was scheduled at 10–12 months for patients with chronic pancreatitis or cholecystectomy and at 4–6 months for patients who received liver transplants. The primary outcome measure was removal success, defined as either scheduled endoscopic removal of the stent with no removal-related serious adverse events or spontaneous stent passage without the need for immediate restenting.ResultsEndoscopic removal of FCSEMS was not performed for 10 patients because of death (from unrelated causes), withdrawal of consent, or switch to palliative treatment. For the remaining 177 patients, removal success was accomplished in 74.6% (95% confidence interval [CI], 67.5%–80.8%). Removal success was more frequent in the chronic pancreatitis group (80.5%) than in the liver transplantation (63.4%) or cholecystectomy (61.1%) groups (P = .017). FCSEMS were removed by endoscopy from all patients in whom this procedure was attempted. Stricture resolution without restenting upon FCSEMS removal occurred in 76.3% of patients (95% CI, 69.3%–82.3%). The rate of resolution was lower in patients with FCSEMS migration (odds ratio, 0.22; 95% CI, 0.11–0.46). Over a median follow-up period of 20.3 months (interquartile range, 12.9–24.3 mo), the rate of stricture recurrence was 14.8% (95% CI, 8.2%–20.9%). Stent- or removal-related serious adverse events, most often cholangitis, occurred in 27.3% of patients. There was no stent- or removal-related mortality.ConclusionsIn a large prospective multinational study, removal success of FCSEMS after extended indwell and stricture resolution were achieved for approximately 75% of patients. ClincialTrials.gov number, NCT01014390.

Clinical Practice GuidelineClinical Practice Guideline on Screening for Colorectal Cancer in Individuals With a Family History of Nonhereditary Colorectal Cancer or Adenoma: The Canadian Association of Gastroenterology Banff Consensus

Background & aimsA family history (FH) of colorectal cancer (CRC) increases the risk of developing CRC. These consensus recommendations developed by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association, aim to provide guidance on screening these high-risk individuals.MethodsMultiple parallel systematic review streams, informed by 10 literature searches, assembled evidence on 5 principal questions around the effect of an FH of CRC or adenomas on the risk of CRC, the age to initiate screening, and the optimal tests and testing intervals. The GRADE (Grading of Recommendation Assessment, Development and Evaluation) approach was used to develop the recommendations.ResultsBased on the evidence, the Consensus Group was able to strongly recommend CRC screening for all individuals with an FH of CRC or documented adenoma. However, because most of the evidence was very-low quality, the majority of the remaining statements were conditional (“we suggest”). Colonoscopy is suggested (recommended in individuals with ≥2 first-degree relatives [FDRs]), with fecal immunochemical test as an alternative. The elevated risk associated with an FH of ≥1 FDRs with CRC or documented advanced adenoma suggests initiating screening at a younger age (eg, 40–50 years or 10 years younger than age of diagnosis of FDR). In addition, a shorter interval of every 5 years between screening tests was suggested for individuals with ≥2 FDRs, and every 5–10 years for those with FH of 1 FDR with CRC or documented advanced adenoma compared to average-risk individuals. Choosing screening parameters for an individual patient should consider the age of the affected FDR and local resources. It is suggested that individuals with an FH of ≥1 second-degree relatives only, or of nonadvanced adenoma or polyp of unknown histology, be screened according to average-risk guidelines.ConclusionsThe increased risk of CRC associated with an FH of CRC or advanced adenoma warrants more intense screening for CRC. Well-designed prospective studies are needed in order to make definitive evidence-based recommendations about the age to commence screening and appropriate interval between screening tests.

Original articleClinical endoscopyCost-effectiveness analysis comparing lumen-apposing metal stents with plastic stents in the management of pancreatic walled-off necrosis

Background and AimsEUS-guided transmural drainage is effective in the management of pancreatic walled-off necrosis (WON). A lumen-apposing metal stent (LAMS) has recently been developed specifically for the drainage of pancreatic fluid collections that shows promising results. However, no cost-effectiveness data have been published in comparison with endoscopic drainage with traditional plastic stents (PSs). Our aim here was to compare the cost-effectiveness of LAMSs to PSs in the management of WON.MethodsA decision tree was developed to assess both LAMSs and PSs over a 6-month time horizon. For each strategy, after the insertion of the respective stents, patients were followed for subsequent need for direct endoscopic necrosectomy, adverse events requiring unplanned endoscopy, percutaneous drainage (PCD), or surgery using probabilities obtained from the literature. The unit of effectiveness was defined as successful endoscopic drainage without the need for PCD or surgery. Costs in 2016 U.S.$ were based on inpatient institutional costs. Sensitivity analyses were performed. An a priori willingness-to-pay threshold of U.S.$50,000 was established.ResultsLAMSs were found to be more efficacious than PSs, with 92% and 84%, respectively, of the patients achieving successful endoscopic drainage of WON. LAMSs, however, were more costly: the average cost per patient of U.S.$20,029 compared with U.S.$15,941 for PSs. The incremental cost-effectiveness ratio favored LAMSs at U.S.$49,214 per additional patient successfully treated. Sensitivity analyses confirmed the robustness of the results.ConclusionLAMSs are more effective but also more costly than PSs in managing WON. Data from high-quality, adequately controlled, prospective, randomized trials are needed to confirm our findings.

Outpatient therapeutic ERCP: a series of 262 consecutive cases☆☆☆★

AbstractBackground: Because of possible complications, it has been common practice to admit most if not all patients undergoing therapeutic ERCP. Therefore, little descriptive data exist on the safety of outpatient therapeutic ERCP.Methods: We assessed 262 consecutive ERCPs in 209 patients undergoing outpatient therapeutic ERCP over a 5-year period, with particular attention to the development of complications. All outpatient endoscopic sphincterotomies and stent placements performed over a 5-year period were prospectively entered into an ongoing data base that was used for the analysis. In addition, hospital and office records for all patients were retrospectively reviewed, including a 30 to 45 day follow-up in a private office setting.Results: Suspected or documented choledocholithiasis was the most common indication for ERCP and was present in 132 (50%), followed by malignant obstruction in 77 (29%), type I sphincter of Oddi dysfunction (on the basis of symptoms, liver test abnormalities, and bile duct dilatation) in 36 (14%), chronic pancreatitis in 10 (3.8%), HIV cholangiopathy in 4 (1.5%), and other conditions in 3 (1.1%). Overall, 181 patients (69%) underwent a sphincterotomy. The 30-day post-ERCP complication rate was 5.7% (95% CI: 3.2% to 9.3%), occurring in 15 of 262 cases. Complications necessitating hospitalization developed in 9 of the 262 ERCPs for a rate of 3.4% (95% CI: 1.6% to 6.4%). The mean duration of hospital stay among patients admitted for a complication was 2.7 ± 1.8 days (range, 1 to 7 days). All patients were discharged without permanent sequelae. No 30-day procedure-related fatalities were reported.Conclusion: In this selected series of 262 consecutive cases, endoscopic sphincterotomy and stent placement were safely performed in an ambulatory setting. Prior to recommending a generalized change in existing practice, however, this finding requires validation with larger series of cases, including the performance of other outpatient therapeutic ERCP techniques. (Gastrointest Endosc 1996;44:443-9.)

Selective cannulation of the common bile duct: a prospective randomized trial comparing standard catheters with sphincterotomes☆☆☆★★★

AbstractBackground:  Current recommendations for the use of standard catheters or sphincterotomes for the initial attempt at selective common bile duct cannulation have been made in the absence of prospective comparative data. Methods:  A prospective study was carried out in which patients were randomized to undergo cannulation with a standard catheter or a sphincterotome (standard or wire-guided). Multivariate models were constructed to determine significant independent predictors of the success rates of initial and selective cannulation and the number of attempts and time needed to achieve selective cannulation. Results:  Eighty-three successive patients were evaluated; 36 were excluded because they had undergone previous therapeutic endoscopic retrograde cholangiopancreatography (ERCP) or a Billroth II operation. Of the 47 patients (28 women, mean age 60.6 ± 14.5 years), indications for ERCP included suspected bile duct stones in 41 patients, pancreatico-biliary malignancies in 4, and biliary leaks in 2. Eighteen patients were randomized to undergo selective common bile duct cannulation with standard catheter and 29 to standard/wire-guided sphincterotome. Initial common bile duct cannulation for the standard catheter and standard/wire-guided sphincterotome groups was successful in 12 (67% [95% CI: 41%, 87%]) and 28 (97% [95% CI: 82%, 100%]) patients, respectively (95% CI for the difference: –0.57 to –0.03, p = 0.009). Using intention to treat analysis, selective common bile duct cannulation was successful for standard catheter and standard/wire-guided sphincterotome patients in 17 (94% [95% CI: 73%, 99%]) and 28 (97% [95% CI: 82%, 100%]) cases, respectively (95% CI for the difference: –0.15 to +0.10, p > 0.05). The mean number of attempts required to achieve selective common bile duct cannulation were 12.4 ± 6.0 and 2.8 ± 3.1 (p = 0.0001). The mean time taken to achieve selective common bile duct cannulation was 13.5 ± 6.14 and 3.1 ± 5.1 minutes (p = 0.0001). Multivariate modeling revealed that the initial choice of catheter was the only significant independent predictor of the time taken and the number of attempts performed to achieve selective common bile duct cannulation (p = 0.0001 for each model). Conclusion:  The use of standard/wire-guided sphincterotome was superior to that of standard catheter for the initial attempt at cannulation of the common bile duct. The number of attempts required may bear clinical significance with regard to the development of post-ERCP pancreatitis and warrants further study. (Gastrointest Endosc 1999;50:775-9.)

Original ArticleSpecific HRQL instruments and symptom scores were more responsive than preference-based generic instruments in patients with GERD

AbstractObjectiveTo determine relative responsiveness of disease-specific and generic preference-based health-related quality of life instruments in gastroesophageal reflux disease (GERD).Study Design and SettingWe compared standardized response means (SRM) of disease-specific and preference-based instruments in 217 outpatients with GERD.ResultsQuality of Life in Reflux and Dyspepsia and symptom scores were responsive across all domains, whereas global rating of change and Work Productivity and Activity Impairment-GERD only in single domains. The most responsive were Quality of Life in Reflux and Dyspepsia food/drink problems (SRM: 1.90, 95% confidence interval [CI]: 1.76–2.03) and vitality (SRM: 1.68, 95% CI 1.55–1.82) domains, Work Productivity and Activity Impairment-GERD workdays with reflux symptoms (SRM: 2.02, 95% CI 1.84–2.19), symptoms of heartburn (SRM: 1.83, 95% CI 1.69–1.96) and acid reflux (SRM: 1.48, 95% CI 1.35–1.62), and global rating of change in stomach problems (SRM: 2.19, 95% CI 2.05–2.32). The least responsive were Work Productivity and Activity Impairment-GERD domains related to hours absent at work (SRM: 0.22, 95% CI 0.05–0.38), reduced productivity at work (SRM: 0.66, 95% CI 0.48–0.83) and during other activities (SRM: 0.78, 95% CI 0.65–0.92), as well as emotional global rating of change (SRM: 0.72, 95% CI 0.58–0.85), and the standard gamble (SRM: 0.35, 95% CI 0.21–0.48), which was less responsive than the feeling thermometer (SRM: 0.92, 95% CI 0.78–1.05).ConclusionsIn patients with GERD, disease-specific health-related quality of life instruments and symptom scores showed greater responsiveness than preference-based generic instruments. The feeling thermometer proved more responsive than the standard gamble.

Evolving management of mild-to-moderate gallstone pancreatitis

AbstractThe objective of this study was to describe recent trends in the management of mild-to-moderate gallstone pancreatitis and assess patient outcomes. Acute gallstone pancreatitis has traditionally been managed with open cholecystectomy and intraoperative cholangiography during the initial hospitalization. The popularization of endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic cholecystectomy has made a reassessment necessary. Two consecutive time periods were retrospectively analyzed: prior to laparoscopic cholecystectomy (prelaparoscopic era [PLE]) and after the diffusion of laparoscopic cholecystectomy (laparoscopic cholectomy era [LCE]). There were 35 patients in the PLE group and 58 in the LCE group. LCE patients waited 37.1 ± 63 days from admission until cholecystectomy, compared to 9.8 ± 14.8 days in the PLE group (P = 0.04). Biliary-pancreatic complications occurred in 24% of LCE patients and only 6% of PLE patients (P = 0.05),nearly always while they were awaiting cholecystectomy (P = 0.009). Patients in either time period who underwent cholecystectomy with intraoperative cholangiography developed less pancreatic-biliary complications than those who underwent ERCP prior to cholecystectomy, with or without sphincterotomy. Delaying the interval from pancreatitis to laparoscopic cholecystectomy beyond historical values is associated with a greater risk of recurrent biliary-pancreatic complications, which are not prevented by the use of ERCP. Early cholecystectomy with intraoperative ductal evaluation is still the approach of choice.

Comparison Costs of ERCP and MRCP in Patients with Suspected Biliary Obstruction Based on a Randomized Trial

AbstractBackgroundThe optimal management of patients with suspected biliary obstruction remains unclear, and includes the possible performance of magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP).ObjectivesTo complete a cost analysis based on a medical effectiveness randomized trial comparing an ERCP-first approach with an MRCP-first approach in patients with suspected bile duct obstruction.MethodsThe management strategies were based on a medical effectiveness trial of 257 patients over a 12-month follow-up period. Direct and indirect costs were included, adopting a societal perspective. The cost values are expressed in 2012 Canadian dollars.ResultsTotal per-patient direct costs were Can$3547 for ERCP-first patients and Can$4013 for MRCP-first patients. Corresponding indirect costs were Can$732 and Can$694, respectively. Causes for differences in direct costs included a more frequent second procedure and a greater mean number of hospital days over the year in patients of the MRCP-first group. In contrast, it is the ERCP-first patients whose indirect costs were greater, principally due to more time away from activities of daily living. Choosing an ERCP-first strategy rather than an MRCP-first strategy saved on average Can$428 per patient over the 12-month follow-up duration; however, there existed a large amount of overlap when varying total cost estimates across a sensitivity analysis range based on observed resources utilization.ConclusionsThis cost analysis suggests only a small difference in total costs, favoring the ERCP-first group, and is principally attributable to procedures and hospitalizations with little impact from indirect cost measurements.

Original article—alimentary tractCost-Effectiveness of Proton-Pump Inhibition Before Endoscopy in Upper Gastrointestinal Bleeding

Background & Aims: Randomized trials suggest high-dose proton-pump inhibitors (PPIs) administered before gastroscopy in suspected upper gastrointestinal bleeding downstage bleeding ulcer stigmata. We assessed the cost-effectiveness of this approach. Methods: A decision model compared high-dose IVPPI initiated while awaiting endoscopy with IVPPI administration on the basis of endoscopic findings. IVPPIs were given to all patients undergoing endoscopic hemostasis for 72 hours thereafter. Once the IV regimen was completed or for patients with low-risk endoscopic lesions, an oral daily PPI was given for the remainder of the time horizon (30 days after endoscopy). The unit of effectiveness was the proportion of patients without rebleeding, representing the denominator of the cost-effectiveness ratio (cost per no rebleeding). Probabilities and costs were derived from the literature and national databases. Results: IVPPIs before endoscopy were both slightly more costly and effective than after gastroscopy in the U.S. and Canadian settings, with cost-effectiveness ratios of US$5048 versus $4933 and CAN$6064 versus $6025 and incremental costs of US$45,673 and CAN$19,832 to prevent one additional rebleeding episode, respectively. Sensitivity analyses showed robust results in the US In Canada, intravenous proton-pump inhibitors (IVPPIs) before endoscopy became more effective and less costly (dominant strategy) when the uncomplicated stay for high-risk patients increased above 6 days or that of low-risk patients decreased below 3 days. Conclusions: With conservative estimates and high-quality data, IVPPIs given before endoscopy are slightly more effective and costly than no administration. In Canada, this approach becomes dominant as the duration of hospitalization for high-risk ulcer patients increases or that of low-risk ulcer patients decreases.

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