bluuebunny/crossref_metadata_2025 huggingface dataset:
A-170 Investigation of High Rate of Low Positive Quantiferon-TB Gold Plus Results
Authors: Mehreen A , Isidan K , Patel D B , Jones K , Laugesen M , Lee H
Published: September 2023

Background

Tuberculosis (TB) is a communicable disease, transmitted almost exclusively by cough aerosols carrying pathogens of the M. tuberculosis complex. TB continues to be a major public health threat, causing an estimated 10.4 million new cases and 1.3 million deaths from TB globally in 2016. Many more people may have latent tuberculosis infection (LTBI), which may go undetected without further laboratory investigation. The Quantiferon-TB Gold Plus (QFT-Plus) is an Interferon Gamma Release Assay (IGRA) for the identification of LTBI. It detects the cellular immune response to antigens of M. tuberculosis and represents an indirect marker of M. tuberculosis exposure. In January of 2021, the NorthShore University HealthSystem Core Laboratory transitioned from a reference laboratory ELISA-based QFT-Plus test to an in-house DiaSorin LIAISON® QuantiFERON®-TB Gold Plus test. After implementation, we noticed a higher rate of low positive QFT-Plus results (1.3%–5.4%) in our patient population that we regard as a mixed risk population. The expected percent of low positive results in a mixed risk population is 2%–3%.

Objective

To determine the potential causes of a higher rate of low positive Quantiferon-TB Gold Plus Results.

Methods

Forty specimens with Antigen-Nil results between 0.35–1.00 IU/mL using LIAISON® QuantiFERON®-TB Gold Plus reagent from 8/2022–10/2022 were collected for this study. All forty specimens were re-tested using ELISA-based methodology. Patient demographics and medical history were reviewed for any factor that may be responsible for the low positive results.

Results

Results from the two different methodologies were compared: 28/40 (70%) specimens showed positive results on the DiaSorin LIAISON®-XL platform, but negative results on the ELISA platform. Review of medical history showed that 92% of the sample population had received more than 2 doses of COVID-19 vaccine and 12.5 % had previous COVID-19 infection. 30% had an underlying autoimmune disease, with psoriasis and rheumatoid arthritis being the most common. However, no correlation was found between medical or vaccination history and the QFT-Plus results.

Conclusion

LIAISON® QuantiFERON®-TB Gold Plus is a Chemiluminescence immunoassay which is more sensitive than ELISA, resulting in an increased number of low positive QFT-Plus results. Physicians need to correlate clinical findings and TB exposure history to the QFT-Plus results when making clinical decisions.
A-184 Racing Against the Clock: Process Improvement Project to Reduce Cardiac Troponin Turnaround Time Through Autoverification of Results
Authors: Tauferner T M , Haga A J , Kelley B R , Wockenfus A M , Donato L J , Karon B S , Katzman B M
Published: September 2023

Background

Turnaround time (TAT), defined as time of collection to time of result verification, is monitored monthly for cardiac Troponin (cTnT). Within our STAT laboratory, our TAT goal is 85% of cTnT results verified within 45 min. In October 2021, our lab began observing an increase in TAT. A quality improvement project was launched to identify a root cause and possible solutions.

Methods

cTnT TAT data from the Hospital Clinical Laboratory (STAT lab) at Mayo Clinic, Rochester, MN was extracted from our Laboratory Information System (LIS) using Tableau (Salesforce Inc., Seattle, WA). The data were categorized into three components: collection time, in lab processing and testing time, and time to result verification. Goal metrics for each component are: collection <10 min, in lab processing and testing <25 min, and result verification to LIS <5 min. The average time for each component and percentage not meeting TAT goals were calculated in Microsoft Excel. TAT while performing manual verification of results (January 2022) and after autoverification was implemented (December 2022) were compared.

Results

Prior to implementation of cTnT autoverification, total orders for January 2022 were 1408 with 82.0% meeting TAT of 45 min. Of the 18.0% not meeting TAT, 207 (14.7%) orders exceeded goals for one or more components (percentages do not total 100%): collection delays 131 (63.0%), in lab processing and testing delay 175 (85.0%), and delay in result verification to LIS 80 (39.0%). For those orders not meeting the 45 min TAT goal, mean times were 17.6, 40.3, and 8 min for collection time, in lab processing and testing, and result verification to LIS, respectively. Post implementation of autoverification, total orders for December 2022 were 1444 with 88.6% meeting TAT of 45 min. Of the 11.4% not meeting TAT, 93 (6.4%) orders were outside goals for multiple components: collection delays 51 (55.0%), in lab processing and testing delay 67 (72.0%), and result verification to LIS 0 (0.0%) orders. For those orders not meeting the 45 min TAT goal, mean times 16.6, 39.7, and 0 min for collection time, in lab processing and testing, and result verification to LIS, respectively.

Conclusion

Achieving TAT goals agreed upon by the laboratory and clinical practice is critical to quality patient care. An investigation into our delayed TAT for cTnT highlighted several opportunities for intervention within the control of the lab. We chose to implement autoverification of results to easily and consistently eliminate the time required for manual result verification. TAT was improved by 6.6% (82.0% to 88.6%) through autoverification of results, allowing technologists to focus on other clinical work.
A-203 An Equation based on the Standard Lipid Panel for Calculating Low-Density Lipoproteins-Triglycerides
Authors: Wolska A , Sampson M , Meeusen J W , Donato L J , Jaffe A S , Remaley A T
Published: September 2023

Background

There is growing evidence that low-density lipoprotein-triglyceride (LDL-TG) may be a better biomarker to define atherosclerotic cardiovascular disease (ASCVD) risk than LDL-cholesterol (LDL-C), which is currently used to stratify risk and as a treatment goal. Because LDL-TG typically requires additional advanced lipid testing, we developed an equation for estimating LDL-TG (eLDL-TG) from the results of the standard lipid panel.

Methods

Results from a general dyslipidemic population (N = 40 202), which were obtained with beta-quantification (BQ) reference method, were randomly divided into a training and validation datasets and used to develop the equation for estimating LDL-TG shown in Fig. 1A. Association of Sampson-NIH-LDL-C (NIH-LDL-C) and eLDL-TG with ASCVD risk markers was done in the National Heart and Nutrition Examination Survey (NHANES) (N = 37 053) and with ASCVD events in the Atherosclerosis Risk in Communities (ARIC) study (N = 14 749).

Results

The comparison between eLDL-TG and measured LDL-TG was only modest (R2 = 0.601, slope = 0.611), but eLDL-TG (Fig. 1B) showed better risk stratification than NIH-LDL-C (Fig. 1C) by survival curve analysis in ARIC. Moreover, receiver-operating characteristic (ROC) analysis showed that eLDL-TG was better than all other lipid-marker tests for ASCVD events (AUC: eLDL-TG = 0.633, HDL-C = 0.627, sdLDL-C = 0.621, remnant-cholesterol = 0.613, NonHDL-C = 0.613, TG = 0.603, apoB = 0.598, NIH-LDL-C = 0.590, TC = 0.568). In NHANES, eLDL-TG was more strongly associated with hypertriglyceridemia, obesity, diabetes, metabolic syndrome and increased high-sensitivity C-reactive protein than NIH-LDL-C. Inclusion of eLDL-TG in a Cox-Proportional Hazards Model along with other conventional risk factors (age, sex, race, diabetes, systolic blood pressure, smoking, HDL-C, and total cholesterol) did not further improve risk prediction.

Conclusions

Like LDL-C, LDL-TG can also be estimated from the results of the standard lipid panel. It is a better univariate risk marker than LDL-C and hence can be useful for initial ASCVD risk stratification.
A-231 Prediction of Severe COVID-19 Based on Routine Biomarker Assessment
Authors: Kapoor H , Bi C , Salm A E , Szymanski J , Goldstein Y D , Wolgast L R , Rosenblatt G , Fox A S , Kroll M H
Published: September 2023

Background

Disease courses in COVID-19 patients vary widely. Prior studies did not focus on initial values of various laboratory biomarkers, instead used data throughout the disease course. Prediction of disease severity based on parameters at the initial diagnosis would aid appropriate management. Objective of our study was to develop predictive models of COVID-19 severity based on demographic, clinical, and laboratory data collected at initial patient contact after diagnosis of COVID-19.

Methods

We evaluated de-identified demographic, clinical, and routine biomarkers data from 14 147 patients with COVID-19 diagnosed by polymerase chain reaction SARS-CoV-2 testing at Montefiore Health System from March 2020 to September 2021. We generated models predicting severe disease (death or more than 90 hospital days) vs mild disease (alive and fewer than 2 hospital days), starting with 58 parameters, by backward stepwise logistic regression.

Results

Of the 14 147 patients, 18% had severe, 24% had mild outcomes and the rest were moderate (cases who were alive but in the hospital for 2–89 days). We identified 4 proficient models in predicting patient outcomes: Inclusive model A, with the largest number (37) of parameters; Receiver Operating Characteristics (ROC) Model B, including 9 parameters with the highest Area under Curve (0.85); the Specific Model C, including 10 parameters with the highest specificity (81%) and Positive Predictive Value and the Sensitive Model D including 9 parameters with the highest sensitivity (91%) and Negative Predictive Value (Tables 1 and 2). The parameters that remained in all models were age, albumin, diastolic blood pressure, ferritin, lactic dehydrogenase, socioeconomic strength, procalcitonin, b-type natriuretic peptide, C reactive protein, d dimer and platelet count.

Conclusions

These findings suggest that certain clinical parameters and routine laboratory biomarkers within the specific and sensitive models could benefit healthcare providers, in their assessment of disease severity and clinical management of COVID-19 infection.
A-266 Evaluation of an Antibody Index Assay for Assessment of Intrathecal Anti-Treponema pallidum IgG Synthesis for the Diagnosis of Neurosyphilis
Authors: Granger D , Theel E S
Published: September 2023

Background

Diagnosis of neurosyphilis (NS) is challenging due to nonspecific clinical symptoms and the lack of a sensitive and specific laboratory test. The non-treponemal Venereal Disease Research Laboratory (VDRL-CSF) assay is a commonly used test in diagnosing NS. An important limitation of the VDRL-CSF is limited specificity, in part due to the inability to differentiate between intrathecally produced antibodies vs passive antibody diffusion into the CSF due to blood-brain barrier (BBB) disruption. Here, we compared the intrathecal synthesis antibody index (AI) of anti-Treponema pallidum IgG antibodies to results from the VDRL-CSF assay in routinely submitted clinical samples for evaluation of suspected NS.

Methods

Paired serum and CSF residual clinical samples from 98 patients with previous VDRL-CSF results were collected. For each pair, the serum and CSF were drawn within 24 h. No additional clinical information and limited supporting clinical test results were available. Thirty-one positive and 67 negative paired samples were tested by an anti-T. pallidum IgG ELISA (Euroimmun, Lübeck, Germany). The AI was calculated using Reiber’s method, with intrathecal total IgG synthesis corrected using the Reiber recommended albumin quotient calculation. Results were compared for positive, negative and overall agreement between methods.

Results

The anti-T. pallidum AI showed a positive, negative and overall agreement of 71.0% (22/31), 100% (67/67) and 90.8% (89/98), respectively, compared to VDRL-CSF. Of note, all nine discordant samples showed abnormally elevated albumin levels in CSF (range: 27.4 to 215 mg/dl; median = 41.7 mg/dl; normal value =<27 mg/dl), indicating a compromised BBB which likely resulted in false-positive VDRL-CSF results. The range and median value for CSF albumin in the 22 concordant samples was 12.4 to 168 mg/dl and 37.2 mg/dl, respectively. In total, 83.9% (26/31) of VDRL-CSF positive samples showed elevated CSF albumin levels which suggests a high percentage of BBB impairment in this patient population. This demonstrates the advantage in specificity that is offered by AI testing compared to use of the VDRL-CSF assay, given the ability of AI to differentiate intrathecally produced vs passively diffused syphilis-specific antibodies. No potential increase in sensitivity was observed in AI testing as 100% negative agreement was obtained.

Conclusion

Our data suggests that establishment of an AI using a treponemal assay to detect intrathecal antibody synthesis provides improved specificity compared to the current commonly performed VDRL-CSF antibody test as an aid in the diagnosis of NS. Further evaluation of sensitivity is warranted using samples from patients with clinically diagnosed NS.
A-280 Impact of 2022 CLSI Revised Piperacillin/Tazobactam Clinical Breakpoints on Enterobacterales Isolates Identified at a Tertiary Medical Center in Southern Taiwan
Authors: Kuo S
Published: September 2023

Background

Piperacillin-tazobactam (TZP) is one of the most common antibiotics administered to hospitalized patients. Its broad activity against gram-negative, gram-positive, and anaerobic pathogens. The Clinical and Laboratory Standards Institute (CLSI) publishes revised TZP breakpoints in 2022. The purpose of this study was to evaluate the impact of changing the TZP breakpoint in a regional teaching hospital in southern Taiwan.

Methods

We retrospectively evaluated TZP for 1347 Enterobacterales isolates identified by MALDI-TOF (Bruker Daltonik, Bremen, Germany) between September 1, 2022, through December 31, 2022, at Chang Gung Memorial Hospital in Chiayi. Blood antimicrobial susceptibility testing was performed using an NMIC-411 panel on the BD Phoenix™ M50. The antibiotic susceptibility test of Enterobacterales from other sources of infection used the Disk diffusion method (Kirby-Bauer Method). Susceptibilities were assessed based on historic CLSI breakpoints in 2021 as well as the current CLSI breakpoints from the most recent CLSI MIC breakpoints, the 32th edition of document M100, published in 2022.

Results

We evaluated 1347 Enterobacterales isolates. Most isolates identified were Escherichia coli [n = 768 (57%)] and Klebsiella pneumoniae [n = 286(21.2%)]. The new TZP breakpoints reduced the percentage of strains that were previously judged to be susceptible by CLSI M100-S31 from 80.9%(1090/1347) to 50%(674/1347). The majority of isolates 674(50%) were susceptible; 416 (30.9%) isolates were susceptible-dose dependent and 257 (19.1%) were resistant to piperacillin/tazobactam using the new CLSI breakpoints. The results of the analysis of the source of infection found that the bacteria that had the greatest impact on the respiratory tract decreased from 43.6% to 12.7%, followed by the genitourinary tract infection decreased from 80.4% to 27%, bodily fluid infection decreased from 69.8% to 24.5%, and abscesses,wounds,pus decreased from 72.7% to 28.1%; The most insignificant are blood infection strains, from 83.1% to 81.3%.

Conclusion

Our results indicate an increase in resistance to Enterobacterales isolates tested. Non- susceptible to piperacillin/tazobactam from 19.1% to 50% using the revised CLSI breakpoints. The decreased susceptibilities make it clear that microbiology laboratories should accept new MIC breakpoints. Although our study has demonstrated decreased susceptibilities, there is no correlation with clinical outcomes. In conclusion, changes in breakpoints had a significant impact on the susceptibility of TZP for Enterobacterales isolates in our study. Understanding and evaluating the impact of the breakpoint changes is of paramount importance. Institutions should ensure that their breakpoints are up to date to allow for the most optimized treatment.
A-281 Analysis of Concurrent HBV Surface Antigen and HBV DNA Test Results
Authors: Pratt G W , Rao L V
Published: September 2023

Background

HBV surface antigen (HBsAg) is the serological hallmark of both acute and chronic infection. HBV DNA levels are monitored clinically in chronic HBV patients to evaluate HBV replication, candidacy for antiviral therapy and monitor patients on therapy. Although HBsAg has an intrinsic association with HBV DNA, it does not necessarily correlate with HBV DNA, especially in the natural course of infection. This study evaluates concurrent HBsAg and HBV DNA testing with a focus on natural infection serological markers such as detection of HBV core antibody (HBcAb), HBV e antigen (HBeAg), and HBV e antibody (HBeAb).

Methods

Clinical laboratory results from 1604 specimens tested over one year for both HBsAg and HBV DNA were analyzed. The HBsAg test is a qualitative assay, but concurrent quantitative HBV DNA results were available. HBV DNA results spanned the measurable range of the assay (lower limit-of-detection: 3.5 IU/mL, lower limit-of-quantitation: 10 IU/mL). HBsAg-positive/HBV DNA-negative results were further investigated to clarify under what circumstances such discordant results are more likely to be observed.

Results

HBsAg-positive and HBV DNA-negative results, which accounted for approximately 18% of the data set (284 out of 1604 samples), are more likely to occur when the specimen is HBeAg-negative (Table). A limitation of this study is a lack of information regarding treatment status of the study population. Additionally, HBsAg can persist during HBV treatment. This discordance between HBsAg and HBV DNA test results could also be due to increased integration of HBV into the host genome that produces HBsAg in the absence of measurable viral load in treatment-naïve individuals.

Conclusion

HBsAg-positive and HBV-DNA negative discordance is most often seen when HBeAg is negative.
A-297 Usefulness of Non-Skin Samples in the PCR Diagnosis of Monkeypox
Authors: Algarate S , Bueno J , Crusells M J , Ara M , Dehesa-García B , García-Manrique B , Alonso H , Alvarado E , Ducons M , Arnal S , Riesgo M , Benito R
Published: September 2023

Background

During 2022, human mpox cases were reported in several European countries. Until November 2022, in Spain, 7404 cases were detected, most of them linked to sexual intercourse. In that context, fast identification of cases and sources of infection were essential for an optimal management. Polymerase chain reaction (PCR) was the preferred laboratory test. Our objective was to evaluate the usefulness of sera and nasopharyngeal samples for MPXV detection, and its application in contact studies without skin or mucosal injuries.

Methods

In the Hospital Clínico Universitario of Zaragoza (Spain), 106 samples from 50 patients, 38 male and 12 female, aged between 11 to 62 years, with skin lesions suspected MPXV infection were analysed. Samples were collected between May and September 2022 in inactivating universal viral transport medium (Biocomma). Samples were obtained between 1 and 19 days of evolution. To perform the real-time PCR, the VIASURE Monkeypox Virus Real Time PCR Detection Kit and the VIASURE 48—Real Time PCR System were used. Nucleic acid extraction was performed with the automated nucleic acid extraction system MagLEAD12gC using the MagDEA®Dx SV reagents.

Results

Table 1 shows the results expressed in Ct values. Skin, anogenital and serum samples were the most efficient for MPXV diagnosis. Nevertheless, these data are influenced by the sample collection date.

Conclusion

Real-time PCR was positive in samples from all locations in 71,4% of the infected patients. Respiratory samples (pharyngeal and nasopharyngeal) were the ones that showed the highest number of false negative results, whereas there was only one skin sample and one serum sample with a negative result. This study shows that sera samples can be used in the diagnosis of MPXV infection because of ease of collection, applicability to contacts without lesions and the option of serology testing for other STI agents (HBV, HCV, HIV, Treponema pallidum…).
A-323 Pre-analytic Interference in PT and PTT Measurement using Mechanical vs Optical Clot Detection
Authors: Maciak D A , Dietzen D J
Published: September 2023

Background

Mechanical clot-detection is commonly thought to be less susceptible to optical pre-analytic interference. Pediatric specimens are particularly prone to be hemolyzed and/or icteric. Our hospital laboratory approached an impending change in coagulation instrumentation from mechanical (STAGO) to optical (IL) with some trepidation. We, therefore, performed a detailed comparison of plasma samples containing a broad range of hemoglobin, bilirubin, and triglyceride using IL reagents (RecombiPlasTin2G, SynthASil) on the TOPS 550 and a manual method on the STart 4.

Methods

7 independent pools (5 normal, 2 prolonged) of residual citrated plasma were supplemented with hemoglobin, bilirubin, or triglyceride up to 1000 mg/dL, 150 mg/dL, or 750 mg/dL, respectively, or with equal volumes of vehicle as control. Supplementation was confirmed and quantified by measuring HIL indices on a Roche Cobas 6000. PT and PTT were performed in duplicate on each experimental and control sample on the TOPS and STart systems. Imprecision of the two systems was monitored at two levels throughout the study.

Results

Imprecision (n = 20) of the TOPS PT and PTT assays ranged from 1.4–3.1% (CV). Imprecision (n = 20) of the STart PT and PTT assays ranged from 1.9–18.3% (CV). PT and PTT on both platforms were not impacted by hemolysis or lipemia up to an H index of 1000 and an L index of 500, respectively. As shown in the Figure, PT and PTT in normal pools on both platforms were significantly prolonged by the presence of bilirubin above an I-index of 30. Results were similar in the prolonged pools. Data points are the means (± SD) of 10 determinations across the 5 normal plasma pools for experimental (●) and control specimens (○).

Conclusion

Mechanical clot detection did not show superior resistance to pre-analytic interference vs an optical clot detection method.
A-339 Utomated Flow of a Non-invasive Fetal Gender Determination Lab-developed Molecular Test
Authors: Xavier Dias T S , da Silva V G , Santos M C , Batistutti V P , Osorio P S , Moratori D , Levi J E
Published: September 2023

Background

The discovery of cell-free fetal DNA in maternal circulation during pregnancy fostered the introduction of non-invasive tests. Fetal gender determination may be determined at early pregnancy by real-time PCR, identifying the presence or absence of Y chromosome markers in maternal plasma. Dasa has been offering this test for more than 10 years. In 2022, the assay was adapted to an automated flow.

Methods

The Flow Solution platform, powered by Roche®, was adapted to the in-house test, allowing the processing of 94 samples. Whole blood is obtained from pregnant women from the 8th week of pregnancy onwards. Each maternal plasma sample is extracted once and the DNA eluate submitted to real-time amplification targeting the DYS14 gene from the Y chromosome, in triplicate. The human RNAseP gene is co-amplified as an internal control. Full process takes 5 hours, with the possibility of overlapping a new routine every 2 hours, with a daily capacity of 12 routines (1128 samples/day).

Results

In 2022, 129 849 fetal gender determination results were released. Of these, 49% of the results indicated male and 51% female fetuses.A few samples displayed indeterminate results, showing amplification curves but with cycle threshold values that are above the cutoff. Other samples do not reach internal quality metrics and the analysis is repeated from the plasma or a new collection is requested. Results that, after the second collection, remain indeterminate, are forwarded with the patient's clinical history to the medical board. In contact with the patient, possible causes for inconclusive results are explained. In 2022, for every 10 000 tests there were 8 were medical contacts.The automated methodology developed and implemented, allowed a high processing volume, with 129 849 tests released in 2022, an increase of 33% compared to 2021 when the method had manual steps. The Total Service Time (TST) from collection to results release in 2022 was approximately 5 days, a 20% reduction compared to 2021, and the repetition rate of 2.43% in 2022 was 0.9% lower than 2021. Recollections also diminished from 1% in 2021 falling to 0.8% in 2022.

Conclusion

A new automated flow was successfully implemented in 2022 improving the productivity and quality of the service, achieving a high accuracy and leading to a significant reduction in errors and repetitions while reducing the turnaround time and recollections.
A-350 Myth Debunked: Same UrineAliquot is not Suitable for hCG Test AfterMicroscopic Analysis
Authors: Li X
Published: September 2023

Background

It has been imparted in the laboratories that the suspending fluid, Lamina, from Iris IQ 200 Analyzer system is prone to interfere with urine human chorionic gonadotropin (hCG) test, especially on a small volume urine specimen. The myth is that the sample is diluted or contaminated by Lamina, which gives falsely negative result for hCG test. An add-on urine pregnancy test was ordered for a specimen, which was completed urinalysis and microscopic analysis. This is the only urine aliquot available, and it is approximately 2mL. This order raised many concerns among laboratory technicians regarding the accuracy of the result. However, no documents or articles were found to support the suspicions. In this study, A serial of experiments was completed to address this concern.

Methods

Known pregnant patients were confirmed their pregnancies with serum hCG tests prior to collecting the urine specimens. The experiment was conducted with 4 positive patient urines. A series of samples ran on DXI 800 system and the point-of-care (POC) Alere hCG combo cassettes. Then the same specimen performed urinalysis and microscopic analysis on Iris IQ 200 Analyzer. To evaluate the Lamina impact, the sample concentrations were verified with point-of-care (POC) Alere hCG combo cassettes and later DXI 800 system. Meantime, the significance of sample size was also evaluated in the study.

Results

The final concentrations of the samples were at <5, 5, 10, 15, 20, 25, 30, 40, 50, and 60 mIU/mL. The cutoff for Alere hCG combo cassettes was verified at 20 mIU/mL for urine, the assay gives the accurate result at and above that value. The results are consistent between immunoassay and POCT prior to and after microscopic analysis. Therefore, no significant interferences were identified with the desired sample volume, 3 mL, or short sample volume, 2mL. The volume usage by iQ 200 Analyzer was less than 500 uL.

Conclusion

In this study, Lamina doesn't cause any interference with hCG values using Alere hCG combo cassettes despite the short sample volume. However, variations between POC urinary hCG devices may contribute to different outcomes. Therefore, a separate validation is highly recommended if a different POC urinary hCG device is involved.
A-386 Performance assessment of Point of care testing for blood glucose: a 5 year review of EQA data
Authors: Thomas M A , Davies G , Blount N
Published: September 2023

Introduction

WEQAS is the largest External Quality Assessment (EQA) provider for the Point of Care Testing (POCT) market within the UK supplying samples and assessment to over 30 000 sites per month with over 20 Programmes across the entire Health care sector. All the Programmes are accredited to ISO 17043.The aim of the programme is to provide support to POCT co-ordinators, to identify non compliant sites and improve the analytical performance of users. Most of the programmes are designed to allow the full assessment of all the devices within the organisation at either monthly, bimonthly or quarterly intervals. A Co-ordinator in each organisation is given a Group Administrator function for the EQA website and maintains the database for its own organisation. The role of performance surveillance is therefore devolved to each individual Co-ordinator at a local level and monitored nationally by the EQA organiser. The powerful database gives POCT Co-ordinators a wealth of information on method and analyser performance both within their own organisation and between organisations. Organisation performance summary reports, distribution letters, non-compliance reports, poor performance reports and cumulative reports are generated from one system. The POCT Users are also provided with a simple traffic light system with clear action limits. For the POCT glucose programme one sample is distributed each month with samples covering a range of 2 to 28 mmol/l annually.

Methods

A review of performance was undertaken between January 2018 and January 2023 for the POCT glucose Programmes for a selection of devices. Devices that were no longer available were excluded as were devices with <50 users in the group. This represented data from 10 360 devices per month in 2018 and 12 277 in 2023. Performance was assessed as the coefficient of variation (CV%) for the device group after outlier exclusion and calculated for a wide range of glucose concentrations.

Results

For devices with CV less than 5% in 2018 there was generally no further improvement in performance, however at a glucose of 2 mmol/L an improvement in performance of 0.5to 3.5% was observed for the other devices. In 2018 CVs ranged from 3.7 to 12% and 3.1 to 8.3%% at 2.5 and 26 mmol/L respectively compared with 4 to 10.3% and 3.3 to 7.2% in 2022.

Conclusion

Although there were numerous examples where EQA identified poor performance at an individual user level, there was little evidence to suggest that the performance of POCT glucose devices had improved significantly over the last 5 years.
A-390 Implementation of the New GEM Hemochron 100 Point-of-care Coagulation System for Heparin Monitoring During Cardiopulmonary Bypass Procedures
Authors: Sheffield A , Oldendorp G , Jordan M , Mast D , Losos M , Siddiqui I , Stieglitz H
Published: September 2023

Background

The Ohio State University Wexner Medical Center has monitored the administration of unfractionated heparin (UFH) during cardiopulmonary bypass (CPB) procedures with the activated coagulation time test, using the Hemochron Signature Elite (Elite) instrument (Werfen) with the ACT+ cartridge. An assessment was conducted to evaluate the performance of the newest Hemochron model, the GEM Hemochron 100 (Werfen), to upgrade current instruments.

Methods

Precision and Methods Comparison studies were conducted with nine GEM Hemochron 100 systems. Each GEM Hemochron 100 instrument was analyzed with two levels of directCHECK liquid quality control, five replicates, over four days. The Method Comparison study compared the results from one Elite system's result, against the average result reported from one to three GEM Hemochron 100 systems. This methodology was repeated in multiple groups, using different Elite and GEM Hemochron 100 systems. All tests were performed with the ACT+ assay, which is sensitive to UFH from 1–6 IU/mL.

Results

Precision: All nine GEM Hemochron 100 instruments yielded: Level 1 CV ≤ 9.5%, and Level 2 CV ≤ 2.5%. Method Comparison: Total datasets 66; range 94–902 seconds; estimated bias at the 300, 420, and 480 second ACT+ clinical decision points were 1.6, 3.2, 4.1 seconds respectively; correlation (r) 0.97; slope 1.01; average CV across GEM Hemochron 100 systems 6.0%.

Conclusion

The performance of the new GEM Hemochron 100 system demonstrated acceptable agreement compared to the Elite system during CPB, maintaining existing ACT+ procedural target times. Results of system performance were consistent with the manufacturer's package insert, as well as previously published data. Based on the clinical performance, GEM Hemochron 100 systems have been implemented into our surgical suites.
B-026 Evaluation of Colorimetric and Electrolyte Test Assays on the Fuji Dri-Chem NX700I Clinical Chemistry Analyzer
Authors: Theologou P , Wichert R , Zacchini F , Moennikes R , Wahl H
Published: September 2023

Background

The FUJI DRI-CHEM NX700i holds 28 colorimetric and 3 electrolyte test assays and analyzes up to 190 tests/hour (colorimetry + electrolytes). A STAT testing position is available. The colorimetric method slide is a multilayered slide composed of dry chemical ingredients needed for the reaction quantifying enzymes and substrates by colorimetric methods. The potentiometric method slide contains ion selective film electrodes. Calibration is done with QC cards except for CRP working with a calibrator. Each test needs 10μL of sample except for CRP (5 μL) and ISE (50μL for all 3 tests).

Methods

In this study the Fuji Dri-Chem NX700i was evaluated using serum samples. The parameters investigated were albumin (ALB), blood urea nitrogen (BUN), creatinine (CRE), total bilirubin (TBIL), aspartate aminotransferase (AST/GOT), Alanine Aminotransferase (ALT/GPT), γ-glutamyltransferase (GGT), C-reactive protein (CRP), lipase (LIP), triglycerides (TG) and ammonia (NH3). Interferences from hemolytic, lipemic, icteric or highly elevated total protein samples were excluded according to the manufacturers method specific declarations and studied separately. Method comparison was done by measuring 50 samples for each analyte at the same time on the NX700i and the Siemens Atellica CH analyzer. For each parameter inter- (controls, n = 10) and intra-assay (patient samples, n = 10) coefficients of variation (CV) were calculated for low, medium and high concentrations.

Results

Inter-assay CVs (n = 10) were 1.1 to 7.7% (Low), 0.7 to 3.9% (Medium) and 0.8 to 5.5% (High). Intra-assay CVs (n = 10) were <0.01 to 9.5% (Low), <0.01 to 3.7% (Medium) and 0.7 to 3.3% (High). Method comparison (Passing-Bablok Regression) of routine samples from hospital patients revealed good agreement of the two methods with correlation coefficients of r = 0.98 and higher except for LIP (0.83), NH3 (0.87) and Alb (0.93).

Conclusion

The FUJI DRI-CHEM NX700i shows good intra- and inter-assay precision with low CVs and excellent correlation with the Siemens Atellica CH analyzer.
B-028 Clinical Performance of a Fully-Automated Fecal Calprotectin Chemiluminescence Immunoassay (CLIA)
Authors: Petzke J A , McDermott B , Thienes C , Veenstra K , Wisherd C
Published: September 2023

Background

Fecal calprotectin is a noninvasive marker for inflammatory bowel disease (IBD). Traditionally, calprotectin is measured by the well-established enzyme linked immunosorbent assay (ELISA) method. More recently, advances in fully automated platforms allow for comparable performance and diagnostic accuracy whilst improving laboratory efficiency. In this study, we assessed the diagnostic performance of the fully automated ALPCO calprotectin chemiluminescence immunoassay (CLIA), and compared it to the predicate, ALPCO’s 510(k) cleared manual calprotectin chemiluminescence ELISA.

Methods

Fecal calprotectin levels were measured with the ALPCO Calprotectin Chemiluminescence ELISA and the recently developed ALPCO Calprotectin CLIA, utilizing glow and flash chemiluminescence, respectively. An IRB approved study included over 400 individuals with clinical suspicion of IBD. The estimates of clinical sensitivity, and clinical specificity of the ALPCO Calprotectin Chemiluminescence ELISA and the ALPCO Calprotectin CLIA were determined by comparing analytical test results of the prospectively collected stool specimens against the clinical diagnosis made by the clinical investigator/gastroenterologist with ileocolonoscopic and histopathological sampling (reference standard).

Results

When distinguishing IBD from irritable bowel syndrome (IBS) and healthy persons, the sensitivity (70/76) and specificity (322/348), at a fecal calprotectin cut-off level of 50 µg/g, were 92.1% and 92.5%, respectively for the ALPCO Calprotectin Chemiluminescence ELISA. Sensitivity (73/78) and specificity (319/342), at a fecal calprotectin cut-off level of 50 µg/g, were 93.6% and 93.3%, respectively for the ALPCO Calprotectin CLIA.

Conclusion

The ALPCO Calprotectin CLIA showed comparable clinical performance for detection of IBD compared to the predicate 510(k) cleared ALPCO Calprotectin Chemiluminescence ELISA. The automation of the ALPCO calprotectin immunoassay allows for increased laboratory efficiency without sacrificing diagnostic accuracy.
B-031 Digital Elisatotal 25-Hydroxyvitamin D
Authors: Chae S , Chung J , Huh H , Moon S , Seo Y
Published: September 2023

Evaluation of digital ELISA using a high-resolution computational optical system for measurement of total 25-hydroxyvitamin D

Background

Biomarkers such as vitamin D occur at very low concentrations in blood, and sensitive detection methods are required in order to measure them. It is difficult to accurately measure low-concentration biomarkers using conventional enzyme-linked immunosorbent assays (ELISA) with fluorescence staining. By developing a digital ELISA (DELISA, Small Machines, Seoul, Korea) platform, a low concentration substance was realized by analyzing the digitalized signal through a high-resolution computational optical system in a microfluidic chip. We evaluated DELISA for measurement of total 25-hydroxyvitamin D (25OHD) in a fluidic chip.

Methods

The sample with monoclonal antibody bead conjugates mixture was incubated for 20 min at 37°C, then 30 uL sample mixture was applied to inlet of the chip. After additional incubation for 2 min at room temperature and 2 min after sample application, 120 uL of washing buffer was applied onto the washing hole and the chip was incubated for 10 min. 25OHD molecules in the sample bond to magnetic beads coupled with anti-25OHD at the end of the membrane. Chips were inserted into DELISA, and 25OHD results were derived by analysis of the computational method of microscopic imaging, proportional to the concentration of 25OHD. Assay performance characteristics of the limit of detection (LoD), precision and analytical measurement interval (AMI) using Vitamin D Depleted, Low and High Serum (Molecular Depot, San Diego, CA) were determined according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. 87 Samples for method comparison studies were obtained from routine clinical samples submitted for 2 OHD determination or from apparently healthy normal volunteers. The study was approved by the Institutional Review Board of Dongguk University Ilsan Hospital (202207024).

Results

LoD was 10.3 ng/mL and within-laboratory precision was 11, 12, and 10% coefficient of variation at 14.1, 56.6, and 113.2 ng/mL, respectively. The best fit polynomial was a cubic equation from 14.1 to 113.2 ng/mL and the difference between the third-order equation and the first-order equation at Level 3 and 4 concentrations was outside the non-linearity limit. Comparison with chemiluminescent assay (Elecsys Vitamin D total II, Roche Diagnostics, Mannheim, Germany) yielded a 0.904 of correlation coefficient and 0.921 slope in the range from 7.0 to 57.9 ng/mL.

Conclusions

The DELISA 25OHD assay has a suitable LoD and precision, however, it is necessary to improve the AMI at high concentration values and correlation with the automated analyzer.
B-071 Comparison of Humoral and Cellular Immune Responses Between ChAd-BNT Heterologous Vaccination and BNT-BNT Homologous Vaccination Following the third BNT Dose: A Prospective Cohort Study
Authors: Kang H , Sim W , Jung J , Lee J , Ko G , Park H , Cha K , Choi J , Park K , Oh E
Published: September 2023

Background

The differential immune responses after two additional BNT162b2 (BNT) doses between ChAdOx1 nCoV-10 (ChAd)-primed and BNT-primed groups have not been elucidated. The aim of this study was to compare vaccine-induced humoral and cellular immune responses and evaluate breakthrough infection between the two vaccination strategies.

Methods

In 221 healthy subjects (111 in the ChAd group), longitudinal immune responses were monitored at 3, 4, and 6 months after the 2nd dose and 1, 3, and 6 months after the 3rd dose. Humoral immunity was measured by two fully automated chemiluminescent immunoassays (Elecsys and Abbott) and a surrogate virus neutralization test (sVNT). Cellular immunity was assessed by two interferon-γ (IFN-γ) release assays (QuantiFERON SARS-CoV-2 and Covi-FERON).

Results

After the 2nd dose of BNT vaccination, total antibody levels were higher in the ChAd group, but IgG antibody and sVNT results were higher in the BNT group. Following the 3rd dose vaccination, binding antibody titers were significantly elevated in both groups (ChAD-BNT; 15.4 to 17.8-fold, BNT-BNT; 22.2 to 24.6-fold), and the neutralizing capacity was increased by 1.3-fold in both cohorts. The ChAd-BNT group had lower omicron neutralization positivity than the BNT-BNT group (P = 0.001) at 6 months after the 3rd dose. Cellular responses to the spike antigen also showed 1.7 to 3.0-fold increases after the 3rd dose, which gradually declined to the levels equivalent to before the 3rd vaccination. The ChAd cohort tended to have higher IFN-γ level than the BNT cohort for 3–6 months after the 2nd and 3rd doses. The frequency of breakthrough infection was higher in the ChAd group (44.8%) than in the BNT group (28.1%) (P = 0.0219). Breakthrough infection induced increased humoral responses in both groups, and increase of cellular response was significant in the ChAd group.

Conclusion

Our study showed differential humoral and cellular immune responses between ChAd-BNT-BNT heterologous and BNT-BNT-BNT homologous vaccination cohorts. The occurrence of low antibody levels in the ChAd-primed cohort in the humoral immune response may be associated with an increased incidence of breakthrough infections. Further studies are needed on the benefits of enhanced cellular immunity in ChAd-primed cohorts.
B-111 Parallel Detection of Antibodies against CDR2L and CDR2 Increases the Diagnostic Specificity in Serological Diagnostics of Paraneoplastic Cerebellar Degeneration
Authors: Venkataraman I , Ott A , Scharf M , Miske R , Jäger D , Honnorat J , Komorowski L , Scheper T , Meyer W
Published: September 2023

Background

Onconeuronal anti-Yo antibodies are key diagnostic markers for paraneoplastic cerebellar degeneration (PCD) and often associated with gynaecologic/breast cancer. Cerebellar degeneration-related protein 2-like (CDR2L), but not cerebellar degeneration-related protein 2 (CDR2), has recently been shown to be the major anti-Yo target (1, 2). This study investigated if inclusion of CDR2L in diagnostic tests results in increased specificity for PCD.

Methods

Three panels were examined for reactivity against CDR2L and CDR2 by line blot analysis (EUROLINE). Panel A comprised 14 preselected sera from women with Yo-specific reactivity by indirect immunofluorescence assay (IFA) on rat cerebellum, presenting with cerebellar ataxia (n = 13) or peripheral neuropathy (n = 1) and underlying gynaecologic/breast cancers (n = 14). Panel B included 2132 non-selected consecutive serum/CSF samples from patients with neurological symptoms. Panel C consisted of 150 samples from healthy blood donors.

Results

In Panel A, all samples (100%) from patients with typical clinical characteristics for Yo-associated PCD showed strong positive reactivity to both CDR2L and CDR2. In Panel B, seven (0.3%) sera were anti-CDR2 negative, but anti-CDR2L positive, all of them from patients (6M/1F) without PCD and two with cancer or pre-cancerous condition. Eleven (0.5%) patients (9M/2F) were found to be anti-CDR2 positive, but anti-CDR2L negative, including two with cerebellar ataxia and three with cancer or pre-cancerous condition. In all 18 cases, IFA on rat cerebellum was negative, suggesting non-specific line blot reactivity to CDR2L or CDR2. In Panel C, 0/150 sera were anti-CDR2L and 1/150 anti-CDR2 positive, corresponding to specificities of 100% and 99.3%, respectively. The anti-CDR2 positive blood donor was male with negative IFA result.

Conclusion

Using CDR2L in addition to CDR2 increases the specificity in diagnosing anti-Yo-associated PCD. Positive line blot reactivity against both parameters seems to confirm the diagnosis. In contrast, results showing isolated reactivity against either CDR2L or CDR2 have to be interpreted carefully as they may apply to non-PCD cases.
B-131 The Prevalence and Clinical Relevance of the DFS Immunofluorescent Staining Pattern in a Large ANA-positive Cohort
Authors: Zhang Y , Rao L V
Published: September 2023

Background

The dense fine-speckled (DFS) nuclear pattern is one of the most common indirect immunofluorescence (IIF) patterns detected during routine antinuclear antibody (ANA) screening. Although various researchers have studied the DFS pattern in recent years, it presents a clinical puzzle since its significance remains elusive. Anti-DFS-70 antibodies occur in healthy individuals with different medical conditions. Unlike the other ANA patterns, they are not associated with systemic autoimmune disease. The present study examined the association of a DFS ANA pattern with the medical conditions of patients who presented to a tertiary care medical center.

Methods

Retrospective chart review of all laboratory values (January 2020 through June 2022) with ANA- and DFS-positive patterns in patients with ANA tests ordered by various clinicians and compared to the patient diagnosis reported. UMass Human IRB approves this study.

Results

Of 8885 ANA samples analyzed, 67.8% (6022) were reported negative. Of total positive ANA (2863) samples, 78.6% (2257) had nuclear patterns, 9.1% (260) had mitotic patterns, and 12.1% (346) had cytoplasmic patterns. Of the positive ANA samples, 14.6% (417) had DFS patterns. For samples with DFS pattern, titers ranged from 1:40 to 1:1280; 62.5% were between1:40, and 1:80. Of samples positive for ANA DFS patterns, 76% (317) were from female patients, and 90% (375) were from patients >21 years of age. Among patients with DFS patterns, the most commonly reported diseases were neurological, followed by respiratory, digestive, circulatory, and musculoskeletal (Table 1).

Conclusion

Clinicians should use a positive ANA with a DFS pattern to indicate pathological phenomena other than autoimmune diseases. Only 3.1% of the patients with DFS patterns have a systemic rheumatic disorder. Clinicians should pay close attention to ANA Patterns, especially DFS staining when using ANA testing.