Characteristics and Outcomes of Patients Undergoing Endoscopy During the COVID-19 Pandemic: A Multicenter Study from New York City.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted the practice of endoscopy, but characteristics of COVID patients undergoing endoscopy have not been adequately described. AIMS: To compare findings, clinical outcomes, and patient characteristics of endoscopies performed during the pandemic in patients with and without COVID-19. METHODS: This was a retrospective multicenter study of adult endoscopies at six academic hospitals in New York between March 16 and April 30, 2020. Patient and procedure characteristics including age, sex, indication, findings, interventions, and outcomes were compared in patients testing positive, negative, or untested for COVID-19. RESULTS: Six hundred and five endoscopies were performed on 545 patients during the study period. There were 84 (13.9%), 255 (42.2%), and 266 (44.0%) procedures on COVID-positive, negative, and untested patients, respectively. COVID patients were more likely to undergo endoscopy for gastrointestinal bleeding or gastrostomy tube placement, and COVID patients with gastrointestinal bleeding more often required hemostatic interventions on multivariable logistic regression. COVID patients had increased length of stay, intensive care unit admission, and intubation rate. Twenty-seven of 521 patients (5.2%) with no or negative COVID testing prior to endoscopy later tested positive, a median of 13.5 days post-procedure. CONCLUSIONS: Endoscopies in COVID patients were more likely to require interventions, due either to more severe illness or a higher threshold to perform endoscopy. A significant number of patients endoscoped without testing were subsequently found to be COVID-positive. Gastroenterologists in areas affected by the pandemic must adapt to changing patterns of endoscopy practice and ensure pre-endoscopy COVID testing.

Donning a New Approach to the Practice of Gastroenterology: Perspectives From the COVID-19 Pandemic Epicenter.

The COVID-19 pandemic seemingly is peaking now in New York City and has triggered significant changes to the standard management of gastrointestinal diseases. Priorities such as minimizing viral transmission, preserving personal protective equipment, and freeing hospital beds have driven unconventional approaches to managing gastroenterology (GI) patients. Conversion of endoscopy units to COVID units and redeployment of GI fellows and faculty has profoundly changed the profile of most GI services. Meanwhile, consult and procedural volumes have been reduced drastically. In this review, we share our collective experiences regarding how we have changed our practice of medicine in response to the COVID surge. Although we review our management of specific consults and conditions, the overarching theme focuses primarily on noninvasive measures and maximizing medical therapies. Endoscopic procedures have been reserved for those timely interventions that are most likely to be therapeutic. The role of multidisciplinary discussion, although always important, now has become critical. The support of our faculty and trainees remains essential. Local leadership can encourage well-being by frequent team check-ins and by fostering trainee development through remote learning. Advancing a clear vision and a transparent process for how to organize and triage care in the recovery phase will allow for a smooth transition to our new normal.

Use of Lumen-apposing Metal Stents for Endoscopic Drainage of Intra-abdominal Fluid Collections in Pediatric Patients.

INTRODUCTION: Intraabdominal fluid collections that previously required surgical intervention can now be drained with less invasive techniques. The use of lumen-apposing metal stents (LAMS) to treat pancreatic pseudocysts and perirectal abscesses has been shown to be a safe and effective technique in adults. We aim to evaluate the indications, outcomes, and complications of the use of LAMS in pediatric patients at our institution. METHODS: A retrospective chart review was performed to study patients up to 18 years of age at the Children's Hospital at Montefiore who underwent drainage of intraabdominal fluid collections with the use of LAMS. The main outcome measures were technical and clinical success and associated adverse events with LAMS placement. RESULTS: Seven patients (2 girls) ranging from 9 to 18 years were identified. Four patients had perirectal abscess postperforated appendicitis and 3 patients had pancreatic pseudocysts. All of the patients had complete resolution of the collections, with no recurrence, and our technical and clinical success rate was 100%. Only 1 patient had mild bleeding after placement that spontaneously resolved. DISCUSSION: Our study demonstrates the efficacy and safety of the use of LAMS for the drainage of intraabdominal fluid collections in pediatric patients, although the number of patients included is limited.

Histologic Analysis of Endoscopic Ultrasound-Guided Through the Needle Microforceps Biopsies Accurately Identifies Mucinous Pancreas Cysts.

BACKGROUND & AIMS: It is a challenge to accurately assess pancreatic cystic lesions (PCLs) and determine their risk. We compared the yield of tissue acquired with endoscopic ultrasound (EUS)-guided microforceps (through the needle tissue biopsy [TTNB]) with that of samples collected by EUS-guided fine-needle-aspiration (EUS-FNA), and the accuracy of analyses of each sample type in the diagnosis of mucinous PCLs. METHODS: We performed a prospective open-label study of 114 consecutive adults (56.1% women; mean age, 64.2 y) undergoing EUS-FNA evaluation of PCLs (mean size, 35 mm) at 7 centers, from June 20, 2016, through August 31, 2018. Samples were collected from each cyst by FNA and microforceps; samples collected by FNA were analyzed by cytology and samples collected by TTNB were analyzed by histology. Acquisition yield was defined as the percentage of specimens collected that were adequate for cytologic or histologic analysis. Diagnoses of mucinous cysts were made based on identification of pancreatic mucinous epithelium by cytology analysis of FNA samples or histologic analysis of TTNB samples. Surgical specimens were used as the reference standard when available. RESULTS: The EUS-guided microforceps were successfully inserted into 97.4% (111 of 114) of PCLs. Tissue acquisition yield was significantly higher with TTNB (95 of 114; 83.3%) than FNA (43 of 114; 37.7%) (P < .001). Sixty-one PCLs were determined to be mucinous based on TTNB analysis (53.5%) vs 11 with FNA analysis (9.6%) (P < .001). Among PCLs categorized as equivocal, based on the level of carcinoembryonic antigen, TTNB analysis found 50% (41 of 82) to be mucinous and FNA analysis found 8.5% (7 of 82) to be mucinous (P < .001). Findings from analyses of samples collected by TTNB were 100% concordant with findings from histologic analysis of surgical specimens (14 of 14), whereas only 3 of 14 findings from analysis of samples collected by FNA were in agreement with findings from surgical specimens (21.4%) (P < .001). Four of 5 mucinous PCLs with advanced neoplasia (80%) were detected with TTNB compared with none with FNA (P = .04). Self-limited intracystic bleeding occurred in 7 patients (6.1%), and acute pancreatitis in 6 patients (5.3%). CONCLUSIONS: In a multicenter prospective study of patients undergoing EUS-FNA for evaluation of PCLs, we found TTNB collection of tissues for histologic analysis to be safe and feasible, with an acquisition yield of 83.3%. Histologic analysis of samples collected by TTNB identified a larger proportion of mucinous PCLs compared with cytologic analysis of samples collected by FNA-even among samples categorized as equivocal, based on the level of carcinoembryonic antigen. More samples collected by TTNB than FNA were found to have advanced neoplasia. Clinicaltrials.gov no: NCT02979509.

Digital Pancreaticocholangioscopy for Mapping of Pancreaticobiliary Neoplasia: Can We Alter the Surgical Resection Margin?

INTRODUCTION: In patients with pancreaticobiliary lesions anticipating surgical resection, digital pancreaticocholangioscopy can be used to identify the extent of disease. This presurgical"mapping" could change the surgical plan and optimize patient care. MATERIALS AND METHODS: Patients with pancreaticobiliary lesions anticipating surgery who underwent endoscopic retrograde cholangiopancreatography with digital pancreaticocholangioscopy from 9 international centers were included. Primary outcome was whether pancreaticocholangioscopy altered the surgical plan. Secondary outcome was correlation between surgical and endoscopic histology and adverse events. RESULTS: A total of 118 patients were included (64% male, mean age 69 y): cholangioscopy in 105 patients (89%), pancreatoscopy in 13 patients (11%). Pancreaticocholangioscopy changed the surgical plan in 39 (34%) of patients: 8 of 13 in the pancreatic duct, 32 of 105 in the bile duct. In the bile duct, 6 patients (5%) had less extensive surgery, 26 patients (25%) avoided surgery. In the pancreatic duct, 4 patients (31%) had more extensive surgery and 4 patients (31%) had less extensive surgery. Four patients with downstaged surgery had positive margins on surgical resection; 1 required additional surgical intervention. Overall correlation between endoscopy and surgical histology was 88%. Adverse events included post endoscopic retrograde cholangiopancreatography pancreatitis in 3 patients (2.5%). CONCLUSION: Digital pancreaticocholangioscopy can be effectively used as a mapping tool to delineate the degree of involvement of biliary lesions before surgical resection, in some cases altering the surgical plan. Prospective studies are needed, especially when downstaging surgery.

Comparison of Endoscopic Ultrasound-Fine-Needle Aspiration and Endoscopic Ultrasound-Fine-Needle Biopsy for Solid Lesions in a Multicenter, Randomized Trial.

BACKGROUND & AIMS: Endoscopic ultrasound with fine-needle aspiration (FNA) is the standard of care for tissue sampling of solid lesions adjacent to the gastrointestinal tract. Fine-needle biopsy (FNB) may provide higher diagnostic yield with fewer needle passes. The aim of this study was to assess the difference in diagnostic yield between FNA and FNB. METHODS: This is a multicenter, prospective randomized clinical trial from 6 large tertiary care centers. Patients referred for tissue sampling of solid lesions were randomized to either FNA or FNB of the target lesion. Demographics, size, location, number of needle passes, and final diagnosis were recorded. RESULTS: After enrollment, 135 patients were randomized to FNA (49.3%), and 139 patients were randomized to FNB (50.7%).The following lesions were sampled: mass (n = 210, 76.6%), lymph nodes (n = 46, 16.8%), and submucosal tumors (n = 18, 6.6%). Final diagnosis was malignancy (n = 192, 70.1%), reactive lymphadenopathy (n = 30, 11.0%), and spindle cell tumors (n = 24, 8.8%). FNA had a diagnostic yield of 91.1% compared with 88.5% for FNB (P = .48). There was no difference between FNA and FNB when stratified by the presence of on-site cytopathology or by type of lesion sampled. A median of 1 needle pass was needed to obtain a diagnostic sample for both needles. CONCLUSIONS: FNA and FNB obtained a similar diagnostic yield with a comparable number of needle passes. On the basis of these results, there is no significant difference in the performance of FNA compared with FNB in the cytologic diagnosis of solid lesions adjacent to the gastrointestinal tract. ClinicalTrials.gov identifier: NCT01698190.

Efficacy and Safety of Digital Single-Operator Cholangioscopy for Difficult Biliary Stones.

BACKGROUND & AIMS: It is not clear whether digital single-operator cholangioscopy (D-SOC) with electrohydraulic and laser lithotripsy is effective in removal of difficult biliary stones. We investigated the safety and efficacy of D-SOC with electrohydraulic and laser lithotripsy in an international, multicenter study of patients with difficult biliary stones. METHODS: We performed a retrospective analysis of 407 patients (60.4% female; mean age, 64.2 years) who underwent D-SOC for difficult biliary stones at 22 tertiary centers in the United States, United Kingdom, or Korea from February 2015 through December 2016; 306 patients underwent electrohydraulic lithotripsy and 101 (24.8%) underwent laser lithotripsy. Univariate and multivariable analyses were performed to identify factors associated with technical failure and the need for more than 1 D-SOC electrohydraulic or laser lithotripsy session to clear the bile duct. RESULTS: The mean procedure time was longer in the electrohydraulic lithotripsy group (73.9 minutes) than in the laser lithotripsy group (49.9 minutes; P < .001). Ducts were completely cleared (technical success) in 97.3% of patients (96.7% of patients with electrohydraulic lithotripsy vs 99% patients with laser lithotripsy; P = .31). Ducts were cleared in a single session in 77.4% of patients (74.5% by electrohydraulic lithotripsy and 86.1% by laser lithotripsy; P = .20). Electrohydraulic or laser lithotripsy failed in 11 patients (2.7%); 8 patients were treated by surgery. Adverse events occurred in 3.7% patients and the stone was incompletely removed from 6.6% of patients. On multivariable analysis, difficult anatomy or cannulation (duodenal diverticula or altered anatomy) correlated with technical failure (odds ratio, 5.18; 95% confidence interval, 1.26-21.2; P = .02). Procedure time increased odds of more than 1 session of D-SOC electrohydraulic or laser lithotripsy (odds ratio, 1.02; 95% confidence interval, 1.01-1.03; P < .001). CONCLUSIONS: In a multicenter, international, retrospective analysis, we found D-SOC with electrohydraulic or laser lithotripsy to be effective and safe in more than 95% of patients with difficult biliary stones. Fewer than 5% of patients require additional treatment with surgery and/or extracorporeal shockwave lithotripsy to clear the duct.

EUS-guided drainage of postsurgical fluid collections using lumen-apposing metal stents: a multicenter study.

BACKGROUND AND AIMS: Postsurgical fluid collections (PSFCs) are traditionally drained either percutaneously or surgically. Endoscopic drainage offers several advantages compared with either percutaneous or surgical approaches, including avoiding repeat surgery or the need to have a percutaneous drain in place for weeks. There are very little data regarding the use of lumen-apposing metal stents (LAMSs) in the drainage of PSFCs. We aim to study the technical and clinical success and adverse events (AEs) of using LAMSs in the drainage of PSFCs. METHODS: Collaborators from 8 centers retrospectively reviewed their endoscopic databases to find procedures using LAMSs for drainage of PSFCs. Technical success (successful placement of LAMSs into the fluid collection), clinical success (complete resolution of the fluid collection on repeat imaging or endoscopy), and intraprocedure and postprocedure AEs were measured. RESULTS: Forty-seven patients were identified with PSFCs after various surgeries. Thirteen patients had failed previous percutaneous or surgical drainage attempts. Fluid collections averaged 78.6 mm (range, 47-150 mm) in size. The most common site of stent placement was transgastric, followed by rectum and duodenum. Technical success rate was 93.6% and clinical success rate 89.3%. The intraprocedural AE rate was 4.25% and postprocedural AE rate 6.4%. There was 1 death unrelated to the procedure. CONCLUSIONS: The use of LAMSs to drain PSFCs has a high technical and clinical success rate with low AEs. For collections that are favorably located adjacent to the stomach, duodenum, or rectum, LAMS placement is a viable alternative to repeat surgery or percutaneous drainage.

Endoscopic Therapy With Lumen-apposing Metal Stents Is Safe and Effective for Patients With Pancreatic Walled-off Necrosis.

BACKGROUND & AIMS: Endoscopic ultrasound-guided transmural drainage and necrosectomy have become the standard treatment for patients with pancreatic walled-off necrosis (WON). Lumen-apposing metal stents (LAMS) have shown success in the management of pancreatic fluid collections. However, there are few data on their specific roles in management of WON. We investigated the efficacy and safety of LAMS in treatment of WON. METHODS: We performed a retrospective multicenter case series of 124 patients with WON who underwent endoscopic transmural drainage by using LAMS at 17 tertiary care centers from January 2014 through May 2015. Patients underwent endoscopic ultrasound-guided cystogastrostomy or cystoenterostomy with placement of an LAMS into the WON collection. At the discretion of the endoscopist, we performed direct endoscopic necrosectomy, irrigation with hydrogen peroxide, and/or nasocystic drain placement. We performed endoscopic retrograde cholangiopancreatography with pancreatic duct stent placement when indicated. Concomitant therapies included direct endoscopic debridement (n = 78), pancreatic duct stent placement for leak (n = 19), hydrogen peroxide-assisted necrosectomy (n = 38), and nasocystic irrigation (n = 22). We collected data for a median time of 4 months (range, 1-34 months) after the LAMS placement. The primary outcomes were rates of technical success (successful placement of the LAMS), clinical success (resolution of WON, on the basis of image analysis, without need for further intervention via surgery or interventional radiology), and adverse events. RESULTS: The median size of the WON was 9.5 cm (range, 4-30 cm). Eight patients had 2 LAMS placed for multiport access, all with technical success (100%). Clinical success was achieved in 107 patients (86.3%) after 3 months of follow-up. Thirteen patients required a percutaneous drain, and 3 required a surgical intervention to manage their WON. The stents remained patent in 94% of patients (117 of 124) and migrated in 5.6% of patients (7 of 124). The median number of endoscopic interventions was 2 (range, 1-9 interventions). CONCLUSIONS: On the basis of a retrospective analysis of 124 patients, endoscopic therapy of WON by using LAMS is safe and effective. Creation of a large and sustained cystogastrostomy or cystoenterostomy tract is effective in the drainage and treatment of WON.

Pre- and post-training session evaluation for interobserver agreement and diagnostic accuracy of probe-based confocal laser endomicroscopy for biliary strictures.

BACKGROUND AND AIM: Current diagnostic modalities for indeterminate biliary strictures offer low accuracy. Probe-based confocal laser endomicroscopy (pCLE) permits microscopic assessment of mucosal structures by obtaining real-time high-resolution images of the mucosal layers of the gastrointestinal tract. Previously, an interobserver study demonstrated poor to fair agreement even among experienced confocal endomicroscopy operators. Our objective was to assess interobserver agreement and diagnostic accuracy upon completion of a pCLE training session. METHODS: Forty de-identified pCLE video clips of indeterminate biliary strictures were sent to five endoscopists at four tertiary care centers for scoring. Observers subsequently attended a teaching session by an expert pCLE user that included 20 training clips and rescored the same pCLE video clips, which were randomized and renumbered. RESULTS: Pre-training interobserver agreement for all observers was 'fair' (Κ: 0.31, P-value: <0.0001) and diagnostic accuracy was 72% (55-80%). Post-training interobserver agreement for all observers was 'substantial' (Κ: 0.74, P-value: <0.0001) and diagnostic accuracy was 89% (80-95%). Using a paired t-test, we observed an increase of 17% (95% CI 7.6-26.4) in post-training diagnostic accuracy (t = 5.01, df = 4, P-value 0.007). CONCLUSIONS: Interobserver agreement and diagnostic accuracy improved after observers underwent training by an expert pCLE user with a specific sequence set. Users should participate in such training programs to maximize diagnostic accuracy of pCLE evaluation.

Lemmel Syndrome: Unveiling the Underrecognized Pancreatobiliary Diagnosis, Management Strategies, and Future Directions.

Lemmel syndrome, a rare condition, is characterized by biliary obstruction caused by a periampullary diverticulum (a pouch-like outgrowth of the duodenum near the ampulla of Vater). In our case, a 76-year-old male patient presented with epigastric pain and exhibited a cholestatic pattern on liver function tests. Imaging revealed dilated pancreatic and common bile ducts due to compression by a periampullary diverticulum (double duct sign: simultaneous dilation of the common bile duct and pancreatic duct). Upper endoscopy showed one medium-sized periampullary diverticulum. This case emphasizes the diagnostic process and the importance of considering Lemmel syndrome in differential diagnosis in elderly patients with biliary obstruction. We discuss the prevalence, diagnostic considerations, including imaging modalities, and treatment options, emphasizing the need for further research.

Intensive Care Unit-Related Cholangiopathy-Induced Biliary Cast Syndrome Without Liver Transplantation: A Rare Entity.

The development of biliary cast syndrome (BCS) is very rare, mostly documented in patients with liver transplantation. The etiology of BCS is unknown; however, risk factors include post-liver transplant bile duct injury, ischemia, infection, fasting, parenteral feeding, and increased bile viscosity and gallbladder dysmotility. We present the case of a 41-year-old man who developed BCS secondary to a prolonged intensive care unit course without a liver transplant. This case highlights the importance of monitoring patients with protracted intensive care unit course and abnormal aminotransferases to recognize and timely manage cholangiopathy and BCS-related complications.

Decoding the diagnostic dilemma: Peripheral T­cell lymphoma presenting as acute pancreatitis: A case report.

Peripheral T cell lymphoma (PTCL) is a rare form of non-Hodgkin lymphoma characterized by the origin of mature T-cells. PTCL demonstrates atypical clinical features and involves both nodal and extra-nodal sites. The diagnosis and treatment of PTCL can prove to be challenging, as it is often detected at advanced stages and is resistant to conventional chemotherapy treatments. The present report describes a 55-year-old male patient who presented with acute pancreatitis, and imaging suggested a soft tissue mass in the pancreatic head indicating pancreatic adenocarcinoma. Further investigation through ultrasound-guided biopsy led to the diagnosis of pancreatic PTCL not otherwise specified.

Clinical outcomes of nonvariceal upper gastrointestinal bleeding in nonagenarians and octogenarians: a comparative nationwide analysis.

BACKGROUND/AIMS: Nonagenarians will purportedly account for 10% of the United States population by 2050. However, no studies have assessed the outcomes of nonvariceal upper gastrointestinal bleeding (NVUGIB) in this age group. METHODS: The National Inpatient Sample database between 2016 and 2020 was used to compare the clinical outcomes of NVUGIB in nonagenarians and octogenarians and evaluate predictors of mortality and the use of esophagogastroduodenoscopy (EGD). RESULTS: Nonagenarians had higher in-hospital mortality than that of octogenarians (4% vs. 3%, p<0.001). EGD utilization (30% vs. 48%, p<0.001) and blood transfusion (27% vs. 40%, p<0.001) was significantly lower in nonagenarians. Multivariate logistic regression analysis revealed that nonagenarians with NVUGIB had higher odds of mortality (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.3-1.7) and lower odds of EGD utilization (OR, 0.86; 95% CI, 0.83-0.89) than those of octogenarians. CONCLUSIONS: Nonagenarians admitted with NVUGIB have a higher mortality risk than that of octogenarians. EGD is used significantly in managing NVUGIB among nonagenarians; however, its utilization is comparatively lower than in octogenarians. More studies are needed to assess predictors of poor outcomes and the indications of EGD in this growing population.

Increasing trend of endoscopic drainage utilization for the management of pancreatic pseudocyst: insights from a nationwide database.

BACKGROUND/AIMS: The pancreatic pseudocyst (PP) is a type of fluid collection that typically develops as a delayed complication of acute pancreatitis. Drainage is indicated for symptomatic patients and/or associated complications, such as infection and bleeding. Drainage modalities include percutaneous, endoscopic, laparoscopic, and open drainage. This study aimed to assess trends in the utilization of different drainage modalities for treating PP from 2016 to 2020. The trends in mortality, mean length of hospital stay, and mean hospitalization costs were also assessed. METHODS: The National Inpatient Sample database was used to obtain data. The variables were generated using International Classification of Diseases-10 diagnostic and procedural codes. RESULTS: Endoscopic drainage was the most commonly used drainage modality in 2018-2020, with an increasing trend over time (385 procedures in 2018 to 515 in 2020; p=0.003). This is associated with a decrease in the use of other drainage modalities. A decrease in the hospitalization cost for PP requiring drainage was also noted (29,318 United States dollar [USD] in 2016 to 18,087 USD in 2020, p<0.001). CONCLUSION: Endoscopic drainage is becoming the most commonly used modality for the treatment of PP in hospitals located in the US. This new trend is associated with decreasing hospitalization costs.

Antibody Persistence After Primary SARS-CoV-2 Infection and Protection Against Future Variants Including Omicron in Adolescents: National, Prospective Cohort Study.

BACKGROUND: Antibodies are a measure of immunity after primary infection, which may help protect against further SARS-CoV-2 infections. They may also provide some cross-protection against SARS-CoV-2 variants. There are limited data on antibody persistence and, especially, cross-reactivity against different SARS-CoV-2 variants after primary infection in children. METHODS: We initiated enhanced surveillance in 18 secondary schools to monitor SARS-CoV-2 infection and transmission in September 2020. Students and Staff provided longitudinal blood samples to test for variant-specific SARS-CoV-2 antibodies using in-house receptor binding domain assays. We recruited 1189 students and 1020 staff; 160 (97 students, 63 staff) were SARS-CoV-2 nucleocapsid-antibody positive at baseline and had sufficient serum for further analysis. RESULTS: Most participants developed sustained antibodies against their infecting [wild-type (WT)] strain as well as cross-reactive antibodies against the Alpha, Beta and Delta variants but at lower titers than WT. Staff had significantly lower antibodies titers against WT as cross-reactive antibodies against the Alpha, Beta and Delta variants than students (all P < 0.01). In participants with sufficient sera, only 2.3% (1/43) students and 17.2% (5/29) staff had cross-reactive antibodies against the Omicron variant; they also had higher antibody titers against WT (3042.5; 95% confidence interval: 769.0-12,036.2) than those who did not have cross-reactive antibodies against the Omicron variant (680.7; 534.2-867.4). CONCLUSIONS: We found very high rates of antibody persistence after primary infection with WT in students and staff. Infection with WT induced cross-reactive antibodies against Alpha, Beta and Delta variants, but not Omicron. Primary infection with WT may not be cross-protective against the Omicron variant.

Haemagglutination inhibition and virus microneutralisation serology assays: use of harmonised protocols and biological standards in seasonal influenza serology testing and their impact on inter-laboratory variation and assay correlation: A FLUCOP collaborative study.

Introduction: The haemagglutination inhibition assay (HAI) and the virus microneutralisation assay (MN) are long-established methods for quantifying antibodies against influenza viruses. Despite their widespread use, both assays require standardisation to improve inter-laboratory agreement in testing. The FLUCOP consortium aims to develop a toolbox of standardised serology assays for seasonal influenza. Building upon previous collaborative studies to harmonise the HAI, in this study the FLUCOP consortium carried out a head-to-head comparison of harmonised HAI and MN protocols to better understand the relationship between HAI and MN titres, and the impact of assay harmonisation and standardisation on inter-laboratory variability and agreement between these methods. Methods: In this paper, we present two large international collaborative studies testing harmonised HAI and MN protocols across 10 participating laboratories. In the first, we expanded on previously published work, carrying out HAI testing using egg and cell isolated and propagated wild-type (WT) viruses in addition to high-growth reassortants typically used influenza vaccines strains using HAI. In the second we tested two MN protocols: an overnight ELISA-based format and a 3-5 day format, using reassortant viruses and a WT H3N2 cell isolated virus. As serum panels tested in both studies included many overlapping samples, we were able to look at the correlation of HAI and MN titres across different methods and for different influenza subtypes. Results: We showed that the overnight ELISA and 3-5 day MN formats are not comparable, with titre ratios varying across the dynamic range of the assay. However, the ELISA MN and HAI are comparable, and a conversion factor could possibly be calculated. In both studies, the impact of normalising using a study standard was investigated, and we showed that for almost every strain and assay format tested, normalisation significantly reduced inter-laboratory variation, supporting the continued development of antibody standards for seasonal influenza viruses. Normalisation had no impact on the correlation between overnight ELISA and 3-5 day MN formats.

An external quality assessment feasibility study; cross laboratory comparison of haemagglutination inhibition assay and microneutralization assay performance for seasonal influenza serology testing: A FLUCOP study.

Introduction: External Quality Assessment (EQA) schemes are designed to provide a snapshot of laboratory proficiency, identifying issues and providing feedback to improve laboratory performance and inter-laboratory agreement in testing. Currently there are no international EQA schemes for seasonal influenza serology testing. Here we present a feasibility study for conducting an EQA scheme for influenza serology methods. Methods: We invited participant laboratories from industry, contract research organizations (CROs), academia and public health institutions who regularly conduct hemagglutination inhibition (HAI) and microneutralization (MN) assays and have an interest in serology standardization. In total 16 laboratories returned data including 19 data sets for HAI assays and 9 data sets for MN assays. Results: Within run analysis demonstrated good laboratory performance for HAI, with intrinsically higher levels of intra-assay variation for MN assays. Between run analysis showed laboratory and strain specific issues, particularly with B strains for HAI, whilst MN testing was consistently good across labs and strains. Inter-laboratory variability was higher for MN assays than HAI, however both assays showed a significant reduction in inter-laboratory variation when a human sera pool is used as a standard for normalization. Discussion: This study has received positive feedback from participants, highlighting the benefit such an EQA scheme would have on improving laboratory performance, reducing inter laboratory variation and raising awareness of both harmonized protocol use and the benefit of biological standards for seasonal influenza serology testing.