Clinical Performance Characteristics Research Articles

Prospective, multi-site evaluation of the Cepheid Xpert Xpress CoV-2 plus test on nasal and nasopharyngeal swabs.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to cause millions of infections and tens of thousands of deaths per year in the United States. While the FDA authorized hundreds of SARS-CoV-2 tests during the public health emergency, significantly fewer have made the transition to being cleared or approved. There continues to be a need for FDA-authorized point-of-care SARS-CoV-2 testing that can be performed by untrained users. We conducted a large prospective study of the Cepheid Xpert Xpress CoV-2 plus test for detection of SARS-CoV-2 in both nasal and nasopharyngeal swabs by trained and untrained users. The assay demonstrated excellent clinical performance characteristics and, as a result of this study, was cleared by the FDA.

B-080 Development and Validation of a GQ1b IgG ELISA as a Diagnostic Aid for Subacute Demyelinating Polyneuropathies

Abstract Background Autoimmunity targeting GQ1b is associated with group of disorders that includes Miller-Fisher Syndrome (MFS), Bickerstaff Brainstem Encephalitis (BBE) and classic Guillain Barre Syndrome (GBS) with ophthalmoplegia. Collectively these are referred to as GQ1B-IgG related syndromes. The prevalence of GQ1b-IgG in this population of patients is high and has been reported to be >80% in well-defined clinical cohorts. Clinical phenotypic presentation is diverse and requires highly accurate antibody testing. The objective of this study was to evaluate a newly developed custom GQ1b-IgG assay, using a semi-quantitative ELISA-based method. Methods A GQ1b-IgG ELISA was developed and validated. Patient sera along with assay controls and a single-point calibrator are diluted and incubated in duplicate wells in a 96-well plate coated with GQ1b antigen. The plate is washed and incubated with anti-human-IgG secondary antibody conjugated with HRP. After a colorimetric reaction, optical densities (OD) are read. The OD of patient samples are compared against the calibrator, generating a cut-off index (COI). Samples ≥1.0 COI are considered positive. During the validation phase, analytical and clinical performance characteristics were evaluated. Studies included assessment of imprecision at multiple concentrations of GQ1b-IgG, accuracy using method comparison, analytical sensitivity and specificity, reference range, common interferences, plate drift, and clinical performance in relevant disease and control cohorts. Results Intra-assay imprecision (coefficient of variation; %CV) ranged from 1.0 - 16% across all concentrations of GQ1b-IgG. Inter-assay imprecision (%CV) ranged from 12.4 - 44.5% but was <20% at or above the assay cut-off. We found perfect qualitative agreement with an independent ELISA reference method (20 positive and 20 negative samples selected based on reference method results [reference interval <1:100]). Limit of detection (LOD) was calculated at a COI of 0.22. To assess analytical specificity, 40 samples with high concentrations of immunoglobulins (hypergammaglobulinemia [N=15], IgG M-protein [N=15] and systemic lupus erythematosus [N=10] were tested and all were negative. A reference interval study was performed on 140 healthy donor serums, all were negative. Interference studies were conducted on 2 positive and 2 negative serum samples, spiked for highly hemolytic (1000 mg/dL), lipemic (2000 mg/dL) and icteric (60 mg/dL) conditions. There was no impact on the assay even with high levels of a given interferent. Plate drift on 2 distinct patient pools tested across the plate (COI range 0.7 - 1.3) had overall plate CV’s ≤10%. ROC analysis was performed on a cohort of 278 patient samples (15 MFS cases and 263 controls [suspected demyelinating neuropathy or disease mimics]). A cut-off value of 1.0 (COI) was selected based on the Youden index. At this cut-off, clinical sensitivity for MFS was 87% while clinical specificity was 99.2%. Conclusions The observed performance of the GQ1b-IgG ELISA was acceptable for clinical laboratory implementation. A COI of ≥ 1.0 was selected for clinical use.

Correlation Analysis between Multiple Mini-Interviews during Medical Student Selection and Their Academic Performance

Multiple mini-interviews (MMI) have been used as a tool in the selection of medical students to evaluate their interpersonal and intrapersonal attributes. It is suggested that rigorous evaluation in MMI may predict academic performance during medical training. Thus, this study aims to determine the relationship between MMI scores and subsequent academic performance at the end of the preclinical phase. MMI scores for the academic session 2019/2020 intake in Universiti Putra Malaysia were gathered. The dependent variables were the students’ academic performance at the end of the preclinical phase involving the Professional Examination and Professionalism and Personal Development (PPD) course. No significant positive correlation was observed between MMI and total Professional Examination scores. Total MMI and empathy station scores have a weak positive relationship with objective structured clinical examination (OSCE) marks. There was also a significant positive correlation between resilience station scores and PPD peer assessment marks. In contrast, there was a negative correlation between Malay language station scores and the theory component of Professional Examination marks. This study suggests that MMI has the potential to predict in-programme clinical performance and professionalism characteristics. Studies with larger cohorts are essential to support this evidence.

Cerebrospinal Fluid Biomarkers of Symptomatic Neurosyphilis in People With HIV Compared with Uninfected Individuals.

We evaluated the diagnostic clinical performance characteristics (DCPC) of cerebrospinal fluid (CSF) total protein (TP), white blood cell count (WBC), and lactate (LA) with different cutoff points as adjunct biomarkers of confirmed or presumptive symptomatic neurosyphilis (NS) and the impact of HIV infection. From 5,640 participants who underwent lumbar punctures, 236 participants were included, and classified as either people with HIV (PWH) or people without HIV (PWoH) according to the CDC criteria for confirmed NS (n = 42), presumptive NS (n = 74), systemic syphilis (SS) (n = 38), serological diagnosis of syphilis (n = 18), PWH without SS and NS (n = 10), and negative control (n = 72). In PWoH, for presumptive NS, the combination of CSF TP > 45mg/dL and/or WBC > 5.0 cells/mm3 is valuable for screening, whereas in PWH, it is not recommended for either screening or case-finding NS, however the DCPC were better in the suppressed group. In PWoH, the value of CSF TP > 45mg/dL is adequate for both screening and confirmation of presumptive NS, subject to prevalence. For WBC count > 20 cell/mm3, the positive predictive value (PPV) of the test is almost perfect, suggesting a confirmatory test. In PWH, CSF TP is an inadequate marker of NS. The WBC count, with cutoffs of > 10 or > 20 cells/mm3, was moderately applicable for screening.As conclusions: CSF WBC count and TP showed distinct DCPC in confirmed or presumptive NS, better in the former. These biomarkers could be included for presumptive NS diagnosis. DCPC of these biomarkers for the diagnosis of NS is greatly affected by HIV co-infection.

TARS2 Variants Cause Combination Oxidative Phosphorylation Deficiency-21: A Case Report and Literature Review.

The aim of the study is to explore the clinical and genetic characteristics of the combined oxidative phosphorylation defect type 21 (COXPD21) caused by the TARS2 compound heterozygous pathogenic variants, and to improve clinicians' awareness of the disease. The proband was a girl of first birth, with repeated refractory hypokalemia, hearing impairment, developmental delay, intellectual disability, developmental retardation after infection, high limb muscle tension, and increased serum lactate as the clinical phenotype. The clinical performance, diagnosis, treatment process, and gene characteristics of COXPD21 caused by TARS2 of the case were analyzed, reviewed, and compared with the literature from the CNKI, Wanfang Data, and biomedical literature database (PubMed) until November 2021. The child was diagnosed with COXPD21 after two heterozygous variants in the TARS2 gene were found via whole exome sequencing. One of the variants was c.1679(exon14) A > C (p.Asp560Ala) missense, derived from the mother, and the other was c.1036(exon10)C > T (p.Arg346Cys) missense, derived from the father. The literature was searched and reviewed with the keywords "mitochondrial encephalomyopathy," "TARS2," and "combination oxidative phosphorylation deficiency type 21." A total of four complete domestic and foreign cases were collected from the literature search. COXPD21 onset by a complex heterozygous variant of TARS2 causes refractory hypokalemia, which is rarely reported in China and abroad.

Intraluminal Flow Diverter Design Primer for Neurointerventionalists.

The clinical use of flow diverters for the treatment of intracranial aneurysms has rapidly grown. Consequently, the market and technology for these devices has also grown. Clinical performance characteristics of the flow diverter are well-known to the clinician. However, the engineering design principles behind how these devices achieve ideal clinical performance are less understood. This primer will summarize flow diverter design parameters for neurointerventionalists with the aim of promoting collaboration between clinicians and engineers.

Performance of Anti-Carbamylated Protein Antibody Testing in the Routine Evaluation of Rheumatoid Arthritis from a Single Center.

Detection of anticyclic citrullinated peptide antibodies (anti-CCP) and rheumatoid factors (RF) in sera support the diagnosis of rheumatoid arthritis (RA); however, these markers are not detected in about 20% of RA patients. More recently, antibodies against carbamylated proteins (anti-CarP) have emerged with implications for preclinical RA diagnosis. The objective of this study was to assess the clinical performance of anti-CarP and correlate with disease severity in routine clinical practice. Retrospective chart review of 331 subjects submitted for RA panel serology: 136 clinically defined RA-positive and 195 RA-negative patients. Fifty additional individuals were recruited for healthy controls. Patients' sera were tested for anti-CCP, anti-CarP, and RF antibodies. Clinical performance characteristics were evaluated for anti-CarP individually and in combination with anti-CCP and RF. Documented erosions and synovitis were correlated with anti-CarP positivity. Anti-CarP had a clinical sensitivity and specificity of 27% and 94%, respectively, for established RA. This sensitivity was lower than anti-CCP (79%) and RF (85%). The specificity of anti-CarP was similar to anti-CCP (93%) and higher than RF (69%). Anti-CarP in combination with anti-CCP and RF increased specificity (100%) but decreased sensitivity (21%). There was no correlation of anti-CarP positivity with presence of bone erosions; however, there was an increase in anti-CarP positivity among patients with synovitis. Anti-CarP demonstrates high specificity in diagnosis of established RA but lacks clinical sensitivity. In combination, anti-CarP does not improve clinical performance of anti-CCP and RF but may be useful in anti-CCP negative patients and in identifying patients with more active disease.

Positioning the role of urine cytology within the diagnostic pathway for UTUC: supportive but inconclusive.

With the introduction of kidney-sparing surgery (KSS) for low-risk Upper Tract Urothelial Carcinoma (UTUC), correct risk-stratification has become crucial. High-grade cytology is one of the decisive variables to stratify a tumor as high-risk. To position the role of urine cytology in the diagnostic pathway of UTUC patients, we evaluated the accuracy of urine cytology by comparing the outcomes with histopathology. Patients with UTUC evaluated between 2010 and 2020, and diagnosed by imaging, cytology and histopathology were selected. Descriptive statistics were used to compare cytology with histopathological outcomes using crosstabs. Clinical performance characteristics of cytology were determined for the presence of a malignancy. This study included 176 patients with confirmed histopathological UTUC. Concordance between cytology and biopsy results was found in 14.8% of low-grade tumors and 16.8% of high-grade tumors. Comparing cytology with radical nephroureterectomy (RNU) specimens revealed concordance rates of 1.6% for low-grade tumors and 22.9% for high-grade tumors. Notably, 51.1% of urine cytology results were false negative. Sensitivity for detecting high-grade and low-grade tumors with a positive urine cytology was 56.6% and 52.6%, respectively, with specificities of 54.8% and 37.2%. In the current study, cytology appears to exhibit limited reliability when used as a sole diagnostic tool for assessing tumor grade and consequently risk stratification. It is imperative to recognize these limitations, optimize urine sampling techniques, and leverage a combination of diverse diagnostic methods for the most effective and individualized treatment decision-making.

Clinical performance evaluation of HCV and HIV-1 assays on the fully automated molecular system Alinity m

The demand for molecular virology testing continues to grow in clinical laboratories worldwide. The Alinity m system is a fully automated, continuous, random-access molecular diagnostic analyzer that was designed to streamline the laboratory workflow. In this study, we assessed the clinical performance characteristics of the Alinity m HCV and HIV-1 assays to detect and quantify these two bloodborne pathogens in 71 serum and plasma specimens. The overall qualitative agreement between the Alinity m and Abbott m2000 was 100 % for HCV and 94.4 % for HIV-1. Our data demonstrated a weak bias across the quantitative range of the Abbott m2000 and Alinity m HCV and HIV-1 assays, indicating a strong correlation on viral loads between them. Taken together, the Alinity m HCV and HIV-1 assays had comparable results to their current predecessors, the Abbott RealTime HCV and HIV-1 assays.

B-104 Comparison of the Performance Characteristics of the Third Generation Anti-Cyclic Citrullinated Peptide CCP3.1 IgG/IgA and CCP3 IgG Assays

Abstract Background Rheumatoid arthritis (RA) is one of the most common systemic autoimmune diseases. Anti-citrullinated protein antibody (ACPA) is the most specific serological biomarker for RA and is associated with significantly more disease activity compared to rheumatoid factor (RF). Improved autoantibody detection relied in the generation of tests against cyclic citrullinated peptide (CCP), a subset of ACPA. The 3rd generation anti-CCP IgG antibody (CCP3) emerged with increased sensitivity compared to the earlier versions. More recently, CCP3.1 with conjugate to detect IgA antibodies in addition to the usual IgG antibodies became available. This is described to exhibit enhanced sensitivity due to early RA patients producing IgA antibodies to CCP3 in the absence of IgG. In this study, we evaluated the diagnostic characteristics of CCP3.1 and its association with disease severity in comparison to CCP3. Methods Our cohort included a total of 331 subjects submitted for RA panel or independent antibody testing. Chart review revealed 136 clinically defined RA- positive and 195 RA- negative patients. Residual sera from these patients were tested for RF (Roche Diagnostics, Indianapolis, US), CCP3 and CCP3.1 (Inova Diagnostics, San Diego, US) antibodies. Clinical performance characteristics at the manufacture-suggested cut-off and association with disease severity were assessed and compared between the two assays. Results The overall diagnostic accuracy was comparable between the two assays with CCP3 exhibiting an area under the curve (AUC) of 0.879, 95% CI: 0.836–0.922, and CCP3.1 showed an AUC of 0.890, 95% CI: 0.849–0.931. CCP3 displayed a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 78.7%, 90.8%, 85.6% and 85.9% respectively. CCP 3.1 displayed an equivalent performance with 77.9% sensitivity, 93.3% specificity, 89.1% PPV and 85.8% NPV. Both assays showed an excellent agreement with a positive percent agreement of 92.0% and negative percent agreement of 98.7%. There was a strong quantitative correlation between the two assays (Spearman correlation coefficient, r = 0.864, P < 0.001). Paired t test showed significantly higher titers of CCP3 (mean:118, median:145) compared to CCP3.1 (mean:110, median: 108) in RA patients. RF and CCP3.1 combination yielded a slightly greater specificity (99.0%), positive likelihood ratio (65.9) and odds ratio (201.7) compared to the RF and CCP3 combination (specificity: 98.5%, positive likelihood ratio: 44.5, odds ratio: 138.4). Nine early-RA patients (with symptom onset <6 months of diagnosis) were detected by both assays and displayed comparable titers (CCP3.1, mean:138, median:149; CCP3, mean:149, median:161). Out of 60 RA patients exhibiting more severe disease course with the presence of bone erosions, 50 of them were detected by CCP3.1 (mean:125, median:146) and 51 were detected by CCP3 (mean:139, median:151) and the titers were comparable. Conclusion CCP3 and CCP3.1 assays displayed comparable performance for detection of RA and correlated similarly with the disease severity. In our study cohort that mainly comprised of RA patients diagnosed >6 months after symptoms onset, addition of IgA isotype showed no added value but did not compromise performance.

B-103 A Single Centre Experience of Anti-carbamylated Protein Antibody Testing in the Routine Evaluation of Rheumatoid Arthritis

Abstract Background Rheumatoid arthritis (RA) early diagnosis and treatment can slow disease progression and potentially prevent bone erosion. Anticyclic citrullinated peptide (CCP) IgG and rheumatoid factors (RF) serological testing supports the diagnosis of RA; however, these markers are not detected in about 20% of RA patients. Recently, IgG antibodies against carbamylated proteins (CarP) emerged with implications on preclinical RA diagnosis and disease severity. CarP testing is offered as part of RA panel (CarP, RF and CCP) and as a standalone test in our institution. In this study, we evaluated the contribution of CarP testing for RA diagnosis in our routine clinical practice. Our objectives were 1) to assess the clinical performance of CarP in combination with CCP and/or RF antibodies 2) to understand the association of CarP with disease severity. Methods Our cohort included 331 subjects submitted for RA panel serology. Retrospective chart-review revealed 136 clinically defined RA-positive and 195 RA-negative patients. Patients’ sera were tested for CCP, CarP (Inova Diagnostics, San Diego, US) and RF (Roche Diagnostics, Indianapolis, US) antibodies. Clinical performance characteristics were evaluated for CarP individually and in combination with CCP and RF. Disease manifestations (bone damage and synovitis), were correlated with CarP testing. Results Single antibody testing for CarP differentiated RA patients from disease-controls with a 27.2% sensitivity, 93.3% specificity, 74.0% positive predictive value and 64.8% negative predictive value. When CarP testing was combined with RF, specificity increased to 95.4%, in combination with CCP it increased to 98.5% and in a triple combination with CCP and RF, specificity increased to 99.5%. The specificity observed in CCP and RF combination (98.5%) was equivalent to CCP and CarP combination or CCP, CarP and RF triple combination. Amongst the RA patients, frequency of bone erosions was slightly greater (P = 0.76) in the presence of CarP positivity (19/37, 51.4%) compared to the presence of CCP (51/107, 47.7%) or RF (50/112, 44.6%) positivity in isolation and/or in combination. Frequency of synovitis was higher in RA patients that tested positive for CarP (20/37, 54.1%) compared to patients who tested positive for CCP (44/107, 41.1%) or RF (43/112, 38.4%). In the seronegative subgroup, 17.2% (5/29) of CCP negative and 14.3% (3/21) of RF negative patients were positive for CarP. Six out of 8 patients in this subgroup displayed bone erosions and/or synovitis. Of the early RA- diagnosed patients (< 6 months of symptom onset), 22.2% (2/9) were CarP positive, of which one patient (11.1%) was seronegative for CCP but positive for RF. Conclusion Despite low sensitivity, individual CarP testing offered a specificity comparable to CCP. In combination with CCP and/or RF, CarP displayed a superior specificity compared to any individual testing, however, was inferior to the CCP and RF combination. CarP positivity independently and/or in combination was associated with a severe disease course. These data support the use of CarP in combination with CCP and RF for assessing disease severity but may not be advantageous for initial diagnosis. In CCP or RF seronegative patients, CarP testing may be beneficial in establishing a diagnosis of RA.

133-LB: Proof-of-Concept Study Results with a New Osmotic-Pressure–Based Continuous Glucose Sensor

Background: The Sencell sensor (Lifecare AS, Bergen, Norway) uses glucose induced changes in an osmotic pressure chamber for continuous measurement of glucose concentrations in the subcutaneous tissue. A close to linear correlation between the raw sensor signal and the glucose concentration and a very long duration of use (of up to 6-12 months or longer) are theoretically to be expected. The final device is planned to have the size of a grain of rice and to be implanted employing wireless energy and data transfer. Method: For a first clinical proof of concept study in humans, a wired version of the core sensing technology was embedded into a 4 mm needle and inserted into the abdominal subcutaneous tissue of healthy volunteers. The study was conducted to collect first human proof-of-concept performance data for algorithm development during meal experiments and for further device optimization. The raw data was analyzed after one-point calibration and minor trend correction in comparison to the Statstrip blood glucose meter and the Freestyle Libre 2 glucose sensor. Results: Seven participants (5 female, 2 male, age: 49±11 years) delivered a total of 105 direct comparator data-points (vs. Statstrip blood glucose meter) during repeated meal experiments with observation periods between 2 h and up to 72 days. The osmotic-pressure sensor followed glucose changes similar to the FreeStyle Libre device and reached an MARD of 9.8% in comparison to StatStrip (87 % and 13 % of the datapoints were lying in zones A and B of the consensus error grid, respectively). Conclusions: In this first human proof-of-concept study, the osmotic-pressure based continuous glucose sensor was shown to track s.c. glucose concentrations in a comparable manner as the Libre 2 needle sensor. The clinical performance characteristics of the first wired prototypes provide an encouraging perspective for the upcoming next development steps. Disclosure A. Pfützner: Consultant; Novo Nordisk A/S, Research Support; LifeScan Diabetes Institute, Speaker's Bureau; AstraZeneca, Stock/Shareholder; Lifecare A/S, Diakard. M. Hanna: None. N. Thomé: None. H. Jensch: None. Funding Lifecare AS (LIFC-SEN-001)

Establishing clinical performance characteristics for Duoseq, a new assay for DNA and RNA sequencing.

e15059 Background: Despite advances in genomics and next generation sequencing (NGS), clinical implementation of NGS remains challenging. This challenge is critical in hematologic malignancies where NGS has become an essential part of the clinical workup. Many clinical labs resort to send-out testing that can delay appropriate treatment and drive up the cost of care. To address these issues, we have developed Duoseq as a unified approach for DNA and RNA NGS. Duoseq assesses mutations (single nucleotide variants [SNVs], insertions/deletions [indels] and splice site variants [SSVs]), structural variants, and gene expression using a panel of over 400 genes. It is supplied as a kit that enables preparation of DNA and RNA sequencing libraries in a single workflow performed at the point-of-care. It includes complete bioinformatics support that enables a clinical laboratory with an NGS instrument to perform the assay with a turn-around time of 2-3 days. Duoseq is optimized to work with formalin-fixed, paraffin embedded (FFPE) samples that are the standard fixation practice. Methods: We evaluated Duoseq on four dimensions critical to clinical performance: reproducibility, precision, analytical sensitivity (limit of detection, LoD), and analytical specificity. Identical experiments were run at clinical laboratories of two different institutions. Analytical validation samples included 4 FFPE cell lines and 2 synthetic DNA samples designed to harbor variants of interest at known allele frequencies. Results: We determined the LoD to be 5% mutant allele fraction (MAF) for SNVs, 10% MAF for indels/SSVs, and 10% tumor purity for SVs. Duoseq achieved 100% precision and reproducibility for each variant class for events at or above the LoD. Analytical specificity was 100%, indicating no instances of cross-contamination of samples within or across runs. We further evaluated Duoseq performance in 54 clinical cases of myeloid and lymphoid malignancies compared against clinical results provided by FoundationOne Heme NGS panel. Collectively, we assessed 119 SNVs and 49 indels/SSVs. Duoseq performed with 100% specificity for both SNVs and indels/SSVs. Duoseq achieved 98% sensitivity for SNVs and 96% for indels/SSVs. For example, Duoseq detected TP53 variants in 6 cases of myeloid neoplasms, which has relevance for the 2022 WHO and ICC classifications. Duoseq also identified therapeutically relevant variants in IDH1/2, EZH2, FLT3, KRAS and TET2. Conclusions: This study demonstrates performance characteristics that suggest Duoseq would perform well as a clinical-grade assay. Local laboratory factors that include staffing, case volumes, and reimbursement affect adoption and turnaround times in the individual clinical laboratory. However, we anticipate that Duoseq implementation will accelerate the diagnosis of hematologic malignancies and facilitate rapid, more cost-effective care to improve patient outcomes.

Clinical performance characteristics for bordered foam dressings in the treatment of complex wounds: An international wound dressing technology expert panel review.

The aim of this article is to identify and describe clinical practice performance characteristics for bordered foam dressings in the treatment of complex wounds. Our recently published systematic review of outcomes and applied measurement instruments for the use of bordered foam dressings in complex wounds has led to us identifying a range of important clinical and patient-centred issues related to this dressing class. Specifically, here, we focus on an overview of performance criteria in the areas of application, adhesion, exudate management and debridement functions of bordered foam dressings. Our hope is that by highlighting the clinical performance criteria, future testing standards for wound dressings will more closely match our clinical expectations and, thereby, assist clinicians to make better wound treatment choices based on meaningful and clinically relevant dressing product performance standards. complex wounds, complex wound care, treatment, bordered foam dressings, dressing performance.

Comparison between cerebrospinal fluid biomarkers for differential diagnosis of acute meningitis.

Given the difficulty in the differential diagnosis of acute bacterial meningitis (BM) and viral meningitis (VM), we aimed to compare the ability of cerebrospinal fluid (CSF) biomarkers, such as lactate, glucose, lactate dehydrogenase (LDH), C-reactive protein (CRP), total white blood cell count, and predominance of neutrophils, as single tests to differentiate microbiologically defined acute BM and VM. CSF samples were divided into three groups: BM (n=17), VM (n=14) (both with the etiological agent identified), and normal control groups (n=26). All the biomarkers studied were significantly higher in the BM group than in the VM or control groups (p>0.05). CSF lactate showed the best diagnostic clinical performance characteristics: sensitivity (94.12%), specificity (100%), positive and negative predictive value (100 and 97.56%, respectively), positive and negative likelihood ratio (38.59 and 0.06, respectively), accuracy (98.25%), and AUC (0.97). CSF CRP is excellent for screening BM and VM, as its best feature is its specificity (100%). CSF LDH is not recommended for screening or case-finding. LDH levels were higher in Gram-negative diplococcus than in Gram-positive diplococcus. Other biomarkers were not different between Gram-positive and negative bacteria. The highest level of agreement between the CSF biomarkers was between CSF lactate and CRP [kappa coefficient, 0.91 (0.79; 1.00)]. All markers showed significant differences between the studied groups and were increased in acute BM. CSF lactate is better than the other biomarkers studied for screening acute BM due to its high specificity.

Performance Assessment of a Novel Multianalyte Methodology for Celiac Disease Biomarker Detection and Evaluation of the Serology-Alone Criteria for Biopsy-Free Diagnosis.

Serology plays a vital role in celiac disease (CD) diagnosis, and the latest European guidelines advocate for biopsy-free diagnoses in patients with ≥10× the upper limit of normal (ULN) of anti-tissue transglutaminase (tTG) immunoglobulin A (IgA) antibodies. To assess performance characteristics of a novel automated particle-based multianalyte technology (Aptiva) for anti-tTG and anti-deamidated gliadin peptide (DGP) antibody detection as compared to the traditional enzyme-linked immunosorbent assay (QUANTA Lite). Performance characteristics of the ≥10× ULN anti-tTG IgA criteria for serologic diagnosis of CD were also evaluated. Sera samples from 703 patients were tested for anti-tTG IgA, anti-tTG immunoglobulin G (IgG), anti-DGP IgA, and anti-DGP IgG antibodies on both platforms. In total, 127 patients had medical information and were classified as CD-positive (n = 58) and CD-negative (n = 69) based on biopsy results. Clinical performance characteristics were evaluated. Anti-tTG IgA detection showed equal clinical sensitivity and specificity of 91% sensitivity and 99% specificity on both platforms. Anti-tTG IgG resulted in moderate sensitivity of 69% and 72%, but high specificity of 100% and 94% on Aptiva and QUANTA Lite, respectively. Anti-DGP IgG displayed comparable sensitivity of 90% and 81%, and a specificity of 94% and 99%, on Aptiva and QUANTA Lite, respectively. Anti-DGP IgA demonstrated greater sensitivity on QUANTA Lite (83%) than Aptiva (69%) and similar specificities of 97% and 98% on QUANTA Lite and Aptiva, respectively. At ≥10× ULN levels for anti-tTG IgA, Aptiva displayed a sensitivity of 72% and a specificity of 100%, and QUANTA Lite showed a sensitivity of 69% and a specificity of 100%. Aptiva is a reliable method to measure CD biomarkers with reduced hands-on necessity and high-throughput capabilities. This study supports the use of a ≥10× ULN anti-tTG IgA biopsy-free approach for serologic diagnosis of CD.

Abstract OT3-18-02: Clinical validation of “TriNetra™-Breast” test for breast cancer screening in a prospective, observational, case-cohort study

Abstract Introduction The Standard of Care for early detection of breast cancer in asymptomatic women is screening mammography, which has limitations such as radiation exposure and lower sensitivity to detect cancer in women with high breast density or invasive carcinomas. TriNetra™-Breast is a blood test for the detection of breast cancer associated circulating tumor cells in blood. Previously, this test has been used in a study for breast cancer detection in India, where it has shown a sensitivity of 92.5%. It has since been granted the United States Food and Drug Administration (USFDA) Breakthrough Device Designation, attesting its potential to provide for improved detection of breast cancer. This prospective, observational, case-cohort study will confirm the clinical performance characteristics of the technology in the US population. Patients and Methods The primary endpoint of this study will be to determine the sensitivity and specificity of the test for breast cancer screening, using mammography and histopathology confirmed diagnosis (when relevant) as the reference methods. Women ≥40 years, with no prior diagnosis of any cancer and undergoing screening mammography for breast cancer will be eligible for participation in this study. 700 women, representing the diverse ethnic US population, will be enrolled. Cohort A will have 500 women with BI-RADS score of 1, 2, or 3. Among these 500 participants, the age categories of 40-49 years, 50-74 years and >74 years will have 100, 300 and 100 women respectively. Cohort B will have 100 women with suspicion of DCIS (without a suspicion of simultaneous invasive carcinoma) and 50 women each with BI-RADS score of 4 or 5. These study population numbers will ensure optimal representation of in-situ carcinoma, malignant and benign cases. Blood samples will be collected from the enrolled women for TriNetra™-Breast, within sixty (60) days of the screening mammogram. If biopsy is indicated, sample collection will be required prior to the procedure. The lab investigators will be blinded to the clinical information of all participants, including mammography and histopathology results, while the participants and clinical investigators will be blinded to the TriNetra™-Breast test results. The results of TriNetra™-Breast will be compared with the results of mammography and/or histopathology for performance estimation of the test. Study participants will be followed for clinical outcomes for maximum duration of 2 years. Citation Format: Ulka Vaishampayan, Darshana Patil, Wahida Rahman, Stephanie Patterson, Emilija Mitrikeska, Joe Dib. Clinical validation of “TriNetra™-Breast” test for breast cancer screening in a prospective, observational, case-cohort study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-18-02.

Accurate prostate cancer detection based on enrichment and characterization of prostate cancer specific circulating tumor cells.

The low specificity of serum PSA resulting in the inability to effectively differentiate prostate cancer from benign prostate conditions is a persistent clinical challenge. The low sensitivity of serum PSA results in false negatives and can miss high-grade prostate cancers. We describe a non-invasive test for detection of prostate cancer based on functional enrichment of prostate adenocarcinoma associated circulating tumor cells (PrAD-CTCs) from blood samples followed by their identification by immunostaining for pan-cytokeratins (PanCK), prostate specific membrane antigen (PSMA), alpha methyl-acyl coenzyme-A racemase (AMACR), epithelial cell adhesion molecule (EpCAM), and common leucocyte antigen (CD45). Analytical validation studies were performed to establish the performance characteristics of the test using VCaP prostate cancer cells spiked into healthy donor blood (HDB). The clinical performance characteristics of the test were evaluated in a case-control study with 160 known prostate cancer cases and 800 healthy males, followed by a prospective clinical study of 210 suspected cases of prostate cancer. Analytical validation established analyte stability as well as acceptable performance characteristics. The test showed 100% specificity and 100% sensitivity to differentiate prostate cancer cases from healthy individuals in the case control study and 91.2% sensitivity and 100% specificity to differentiate prostate cancers from benign prostate conditions in the prospective clinical study. The test accurately detects PrAD-CTCs with high sensitivity and specificity irrespective of stage, serum PSA or Gleason score, which translates into low risks of false negatives or overdiagnosis. The high accuracy of the test could offer advantages over PSA based prostate cancer detection.

Rapid, sensitive, and specific lateral-flow immunochromatographic point-of-care device for detection of varicella-zoster virus immunoglobulin G antibodies in fingerstick blood

Varicella zoster virus (VZV) causes childhood chickenpox, becomes latent in sensory ganglia and reactivates years later to cause shingles (Zoster) and postherpetic neuralgia in the elderly and immunosuppressed individuals. Serologic IgG tests can be used to determine if a person has antibodies to VZV from past varicella infection or had received varicella or zoster (shingles) vaccination. Commercial enzyme-linked immunosorbent assays (ELISAs) are currently used for the detection of VZV IgG antibodies in patient serum samples. However, ELISA tests require collection and processing of blood samples in a CLIA laboratory to separate serum or plasma for further testing. In this paper, we describe the development and testing of an antibody based Lateral Flow Immunochromatographic assay (LFA) device for the detection of VZV IgG in fingerstick whole blood. Analytical and clinical analyses were performed to compare the performance characteristics of the Viro VZV IgG LFA (VZV LFA) and the Diamedix VZV IgG ELISA. Analytical studies demonstrated the higher sensitivity of the VZV LFA compared to the ELISA by testing dilutions of the WHO VZV IgG serum International Standard. Clinical performance characteristics of the VZV LFA fingerstick whole blood assay were assessed at three point of care (POC) facilities by untrained users testing samples from 300 prospectively enrolled study subjects. VZV LFA results were compared with results obtained by testing serum samples obtained from the same study participants by the Diamedix VZV IgG ELISA. Two specimens with invalid results by the LFA assay were not included in the LFA performance calculations and nine equivocal ELISA results were included as positive for IgG results. The results from all three POC clinical sites demonstrated the higher sensitivity/positive percent agreement (PPA) (99.26%, 95% CI: 97.34–99.80) of the VZV LFA compared to the Diamedix VZV IgG ELISA (94.08%, 95% CI: 90.72–96.27). The specificity/negative percent agreement (NPA) of the VZV LFA compared to the ELISA test was calculated initially to be 39.29% (95% CI: 23.57–57.59) with 19 discordant test results out of 298 test results between the two assays (17 LFA positive/ELISA negative and two LFA negative/ELISA positive). The PPA and true NPA of the VZV LFA were determined by testing all 298 samples, including the discordant (19) and all concordant negative and positive (279) study subject serum samples, before and after blocking VZV gE antibody sites in the samples by spiking with VZV LFA gE capture antigen. The NPA improved to 100% (95% CI: 74.12–100) after the procedure when compared to the ELISA test results. The comparator ELISA PPA based on the spiking/blocking study remained as 94.08%, (95% CI: 90.72–96.27), comparable to test results from untreated samples.The VZV LFA has been demonstrated to be simple and sufficiently robust for use in CLIA-waived POC facilities by untrained healthcare professionals and to detect VZV IgG in 20 min from fingerstick whole blood. The VZV LFA therefore provides a fast, reliable, and highly sensitive method of determining prior VZV viral infection or varicella and zoster vaccination status.

Effects of feeding CLOSTAT (Bacillus subtilis PB6) on the clinical health, performance, and carcass characteristics of feedlot steers1.

The objectives of this experiment were to evaluate the effects of feeding Bacillus subtilis PB6 on clinical health, performance, and carcass characteristics of feedlot steers. Bos indicus crossbred steer calves (n = 397; 342 kg initial body weight [BW]) were randomly assigned to pens by initial BW; pens (n = 24) were randomly assigned to one of two of the following experimental treatments: 1) no supplemental dietary direct-fed microbial, control (CON; n = 12 pens) or 2) 13 g/steer daily B. subtilis PB6 (CLO; CLOSTAT, Kemin Industries, Des Moines, IA; n = 12 pens). Steers were housed in 12.2 × 30.5 m soil-surfaced pens; pen served as the experimental unit. The percentage of cattle treated once or twice for bovine respiratory disease (BRD) did not differ among treatments (P ≥ 0.27); BRD mortality also did not differ between CON and CLO (P = 0.34). During the receiving period, final BW (P = 0.97), average daily gain (ADG; P = 0.91), dry matter intake (DMI; P = 0.77), and gain:feed (P = 0.79) were not different among treatments. There was a tendency (P = 0.09) for CLO-supplemented steers to be 14% more efficient from days 0 to 14 of the receiving period. Final BW, overall finishing phase ADG, and DMI did not differ by treatment (P ≥ 0.14); ADG was 0.14 kg greater for CLO than CON (P = 0.03) from days 29 to 56 of the finishing period. Gain: feed tended (P = 0.07) to be 7% greater (0.144 vs. 0.141) for CLO than CON throughout the duration of the finishing period, and 6.7% greater (P = 0.08; 0.152 for CLO vs. 0.150 for CON) for the entirety of the experiment. Carcass traits did not differ among treatments (P ≥ 0.31). The results of this experiment suggest that supplementing 13 g/steer daily B. subtilis PB6 may improve feed efficiency in feedlot cattle.