Alinity hq platelet count is not impacted by severe microcytosis.

BACKGROUND: Impedance technology has been shown to overestimate platelet (PLT) count in samples with microcytes, while the optical-fluorescence PLT count (PLT-F) by Sysmex has been suggested to be unaffected by microcytosis. The Abbott Alinity hq analyzer employs multi-dimensional optical PLT counting. Our goal was to assess the accuracy of this technology in microcytic samples. METHODS: Platelet measurements were performed by Alinity hq and the impedance (PLT-I) and PLT-F methods on a Sysmex XN-3000 analyzer on 464 samples. PLT concentration range was 6.56-947 × 109 /L and mean cell volume (MCV) 40.9-123.0 fL. Samples were categorized into normocytic (MCV > 80 fL), microcytic (MCV 65-80 fL), and severely microcytic (MCV < 65 fL) groups. RESULTS: Alinity hq PLT count showed excellent agreement with PLT-F (r = 1.00). Sysmex PLT-I data showed somewhat weaker correlation with both PLT-F and Alinity hq (r = 0.98). Increasing bias between Sysmex PLT-I and PLT-F was seen with decreasing MCV values, with mean bias of 35.2 × 109 /L in severe microcytosis. An inverse relationship was demonstrated between the PLT-I versus PLT-F bias and MCV (p < 0.0001). Consistent mean bias was observed between Alinity hq and PLT-F across all MCV ranges. Mean platelet volume was suppressed or flagged by Sysmex XN in 50% of the samples in the severely microcytic group, and markedly higher red cell distribution width (RDW) was reported compared to Alinity hq (18.1% vs 13.7%, p < 0.0001). CONCLUSION: The Sysmex PLT-I method overestimated the PLT count in samples with severe microcytosis. Alinity hq provided PLT counts and PLT and RBC indices that were not impacted by microcytosis.

Accurate white blood cell differential by Alinity hq: A comparison with flow cytometry and manual differential.

INTRODUCTION: White blood cell (WBC) differential by flow cytometry can report a six-part WBC differential and enumerate blasts. Some modern hematology analyzers are also able to provide a six-part WBC differential (including immature granulocytes). Our goal was to compare the WBC differential obtained by the Abbott Alinity hq hematology analyzer to an 8-color single-tube flow cytometry method and to manual WBC differential. METHODS: Samples from 144 patients were tested with Alinity hq, flow cytometry, and microscopic WBC differential. The WBC count ranged from 1.22 to 359 × 109 /L, and 34 samples were flagged by the analyzer for abnormal WBC morphology. RESULTS: Strong concordance was demonstrated between Alinity hq and flow cytometry for all six components of the differential, with correlation coefficients ranging from 0.86 (basophils) to 1.00 (lymphocytes). Small, clinically insignificant positive difference was observed between Alinity hq and flow cytometry for mature and total neutrophils (2.51% and 1.85%) and eosinophils (0.14%), and small negative difference for immature granulocytes (-0.65%), lymphocytes (-0.61%), and basophils (-0.21%). No bias was detected between the Alinity hq and flow cytometry monocyte counts. Alinity hq and flow cytometry results agreed with the manual differential, apart from small, clinically insignificant differences. Alinity hq nucleated red blood cell concentrations were equivalent with the manual results (r = 0.95, slope = 1.16). The percentage of blasts by flow cytometry demonstrated good correlation and agreement with the manual count (r = 0.99, slope = 1.35). CONCLUSION: Alinity hq has produced accurate six-part WBC differential in this three-way comparison, equivalent to flow cytometry and morphological classification.

Clinical utility of Abbott Alinity hq extended red blood cell parameters in differentiating ß-thalassemia trait and iron deficiency anemia.

INTRODUCTION: The objective of the study was to evaluate the performance of the Abbott Alinity hq advanced multi angle polarized scatter separation (MAPSSTM )-based optical RBC technology, for the differentiation between iron deficiency anemia (IDA) and ß-thalassemia carrier status. METHODS: Four hundred and sixty-four samples were analyzed. 228 were healthy controls, 30 were ß-thalassemia carriers, and 40 were IDA. Receiver operating characteristics analysis evaluated the performance of red cell parameters and mathematical formulas. RESULTS: RBC concentration was the most efficient discriminant (area under the curve; AUC of 0.963, Youden Index of 0.88) followed by red blood cell distribution width in size distribution (AUC of 0.960 and YI of 0.86), and red blood cell distribution width coefficient of variation (AUC of 0.924, and YI of 0.74). The absolute reticulocyte concentration showed good diagnostic efficiency, with AUC of 0.808. Hemoglobin distribution width, the %CV of directly measured cellular hemoglobin concentration, and CHCr, the average hemoglobin concentration of reticulocytes have emerged as novel discriminating parameters, with AUC of 0.749 and 0.785, respectively. The England and Fraser index was the best discriminating mathematical formula based on Youden Index of 0.91. The Ricerca, red blood cell distribution width index, Green and King, and Mentzner Index formulas also showed strong discriminative power. The Shine and Lal index, together with the recent mathematical formula M/H, (ratio of percent microcytic and hypochromic red blood cells) demonstrated moderate performance with AUC of 0.796 and 0.740, respectively. CONCLUSION: Extended red cell analysis delivered by the advanced optical technology on the Alinity hq hematology analyzer has efficient diagnostic utility in the initial discrimination of the two most common microcytic anemias: IDA and ß-thalassemia trait.

Alinity hq platelet results are equivalent with the international reference method in thrombocytopenic samples.

INTRODUCTION: Accurate and precise platelet (PLT) count is critical for the appropriate management of patients with thrombocytopenia. This study evaluated the performance of PLT counting with the Abbott Alinity hq hematology analyzer, which utilizes multi-dimensional optical technology. METHODS: Imprecision, linearity, and accuracy were assessed per CLSI guidelines. Alinity hq PLT results were compared to the international flow cytometry reference method (IRM) in the concentration range of 6.3 to 103.0 × 109 /L. Additional comparisons were made with Sysmex XN-3000 PLT counts: impedance (PLT-I), optical (PLT-O), and optical fluorescent (PLT-F) methods. RESULTS: The average within-run %CV was 4.7% on patient samples with PLT concentrations ranging from 13.1 to 41.7 × 109 /L, and the within-laboratory %CV was 3.6% at the level of 68.2 × 109 /L. Linearity evaluation indicated a maximum deviation of 3.1% from the linear fit in the range of 0.1 to 316.8 × 109 /L. Comparison between Alinity hq and the IRM PLT counts yielded a correlation coefficient of 0.99 and predicted bias of 0.0 and -0.5 × 109 /L at 10.0 and 20.0 × 109 /L transfusion thresholds, respectively. Alinity hq PLT counts also correlated well with Sysmex PLT counts, with strongest correlation obtained with PLT-F and PLT-O (r = .99) methods. CONCLUSION: This study demonstrated excellent analytical performance of Alinity hq PLT counting in thrombocytopenic samples, equivalency with the IRM and strong agreement with Sysmex PLT-F and PLT-O methods. The Alinity hq multi-dimensional optical PLT count is available with every CBC without additional reagents and may help promote efficiency in clinical laboratories.

Performance evaluation of the prototype Abbott Alinity hq hematology analyzer.

INTRODUCTION: The analytical and clinical performance as well as the workflow efficiency of the novel, prototype Alinity hq hematology analyzer was evaluated in the clinical laboratory of Universitair Ziekenhuis Brussel, Department of Hematology, Brussels, Belgium. METHODS: Within-run and within-laboratory imprecision, linearity, and carryover were assessed using clinical blood samples and commercial blood products. Four hundred and seventeen samples were selected for method comparison with Abbott CELL-DYN Sapphire, and for flagging performance analysis in comparison with smear review and manual microscopic white blood cell (WBC) differential. RESULTS: Within-run and within-laboratory imprecision verification demonstrated low %CV for complete blood count and WBC differential results within the normal ranges (0.1%-10.4%), except for basophil granulocytes. The linearity of the analytical measuring ranges was verified for WBCs, red blood cells, hemoglobin, and platelets. Alinity hq results showed strong agreement with those of CELL-DYN Sapphire. Good correlation was demonstrated with manual WBC differential results, with negative bias for neutrophil (NEU) granulocytes, and positive bias for lymphocytes and monocytes. Blasts were detected with 75% sensitivity and 96% specificity at 1% blast threshold, and 100% sensitivity at 5% blast threshold. Immature granulocyte detection was more sensitive (81% vs 76%, P = 0.086) and specific (88% vs 78%, P = 0.0002) than with CELL-DYN Sapphire. Nucleated red blood cell detection was more sensitive (89% vs 63%, P < 0.001) and just slightly less specific (96% vs 99%, P = 0.0067) than with CELL-DYN Sapphire. Re-run and reflex testing rates were lower with Alinity hq. CONCLUSION: The Alinity hq hematology analyzer is suitable for clinical use.

Multicenter performance evaluation of the Abbott Alinity hq hematology analyzer.

Background Alinity hq (Abbott) is a new high-throughput hematology analyzer that exclusively employs optical principles for detecting and enumerating blood cells. It reports 29 parameters, including a six-part white blood cell (WBC) differential. The aim of this multicenter study was to evaluate the analytical and clinical performance of the Alinity hq. Methods Complete blood count (CBC) results and morphological flagging were compared to that of CELL-DYN Sapphire (Abbott) and 2 × 200-cell manual differential results, on 1473 whole-blood samples from a well-defined patient population from three different clinical laboratories in the Netherlands. In addition, within-run and within-laboratory precision, linearity, limit of quantitation, carryover and sample stability were assessed. External quality assessment samples were also evaluated. Results Data analysis demonstrated strong concordance of Alinity hq results with those of CELL-DYN Sapphire for all CBC parameters, except for basophil granulocytes. Alinity hq WBC differential showed high level of agreement with manual differential results and exhibited a better agreement with manual basophil results than CELL-DYN Sapphire. The sensitivity of the Alinity hq Blast flag was 57.6%, equal to the 57.6% sensitivity of the CELL-DYN Sapphire's Blast Alert. When considering samples with ≥5% blasts, the sensitivity of the Alinity hq Blast flag was 70.0%. Analytical performance of Alinity hq was shown to be consistent with state-of-the-art (SOTA) performance characteristics. Conclusions Alinity hq CBC measurands demonstrated good overall agreement with results obtained with CELL-DYN Sapphire, as well as manual WBC differential. The analytical and clinical performance characteristics of Alinity hq make it well suited for clinical laboratories.

Detection of anti-dsDNA antibodies by computer-aided automated immunofluorescence analysis.

INTRODUCTION: NOVA View is a computer aided fluorescence microscope that is used for the automated reading and interpretation of indirect immunofluorescent tests in diagnostic immunology. The objective of the present study was to evaluate the performance of the NOVA View® system for the measurement of anti-dsDNA antibodies using the Crithidia luciliae indirect immunofluorescence test (CLIFT) technology. METHODS: Analytical performance of NOVA View CLIFT was assessed in repeatability (within run) and reproducibility (between runs and instruments) studies. Two hundred-fifty patient samples (N=200 consecutive samples and N=50 samples from systemic lupus erythematosus patients) were tested to evaluate the agreement between results generated with NOVA View CLIFT, and those obtained with manual microscopic reading of the same slides. Positivity rate in SLE was assessed on the 50 SLE samples. RESULTS: The NOVA View system showed high level of repeatability and reproducibility within runs, between runs, and between instruments. Agreement of NOVA View software interpretation and digital image reading results with manual microscopic reading results was 96.0%, and the same positivity rate was obtained on SLE samples by NOVA View digital image reading as that of manual microscopic reading (36.0% vs. 38.0%, respectively). CONCLUSION: Results generated by NOVA View CLIFT were equivalent to those obtained by manual microscopic reading on a large routine sample set. NOVA View demonstrated consistency within and between runs, and between instruments. Automation of CLIFT provides reliability and is a suitable alternative for routine clinical laboratories.

A Clinical Approach for Defining the Threshold between Low and Medium Anti-Cardiolipin Antibody Levels for QUANTA Flash Assays.

The threshold between low and medium antibody levels for anticardiolipin (aCL) and anti-ß2 glycoprotein I antibodies (aß2GPI) for the diagnosis of antiphospholipid syndrome (APS) remains a matter of discussion. Our goal was to create a protocol for determining the low/medium antibody cut-off for aCL antibody methods based on a clinical approach, and utilize it to establish the clinically-relevant low/medium threshold for QUANTA Flash aCL chemiluminescent immunoassay (CIA) results. The study included 288 samples from patients with primary APS (n = 70), secondary APS (n = 42), suspected APS (n = 36), systemic lupus erythematosus (SLE) without APS (n = 96) and other connective tissue diseases (n = 44). All samples were tested for IgG and IgM aCL antibodies with QUANTA Flash CIA, along with traditional enzyme-linked immunosorbent assays (ELISAs) (QUANTA Lite). The assay specific low/medium threshold for QUANTA Flash aCL IgG and IgM assays (i.e., the equivalent of 40 GPL and MPL units) was established as 95 and 31 chemiluminescent units (CU), respectively, based on clinical performance and comparison to QUANTA Lite ELISAs. Agreement between CIA and ELISA assay results improved substantially when the platform-specific low/medium antibody threshold was used, as compared to agreement obtained on results generated with the assay cutoff: Cohen's kappa increased from 0.85 to 0.91 for IgG aCL, and from 0.59 to 0.75 for IgM aCL results. This study describes a clinical approach for establishing the low/medium antibody threshold for aPL antibody assays, and successfully employs it to define 95 and 31 CU, respectively, as the low/medium cut point for QUANTA Flash aCL IgG and IgM results. This study can serve as a model for labs wishing to establish the appropriate low/medium aPL antibody threshold when implementing new aPL antibody assays.

Clinical performance evaluation of a novel, automated chemiluminescent immunoassay, QUANTA Flash CTD Screen Plus.

The QUANTA Flash(®) CTD Screen Plus is a chemiluminescent immunoassay (CIA) for the detection of the major antinuclear antibodies (ANA) on the BIO-FLASH(®) platform. NOVA View(®) is an automated fluorescence microscope that acquires digital images of indirect immunofluorescent assay (IFA) slides. Our goal was to evaluate the clinical performance of the two automated systems and compare their performance to that of traditional IFA. Sera from patients with systemic autoimmune rheumatic diseases (SARD, n = 178), along with disease and healthy controls (n = 204), were tested with the CTD CIA and with NOVA Lite(®) HEp-2 ANA, using both the manual method of reading the IFA slides and the NOVA View instrument. The CTD CIA showed 78.1% sensitivity for SARD, coupled with 94.1% specificity. Manual IFA and NOVA View showed somewhat higher sensitivity (81.5 and 84.8% in SARD, respectively), but significantly lower specificity (79.4 and 64.7%, respectively). Both automated systems displayed somewhat different performance, due to the different principals of ANA detection: IFA with NOVA View digital image interpretation had higher sensitivity, while the CTD CIA showed higher specificity. With the added benefits of full automation, the new CTD CIA is an attractive alternative to traditional ANA screening.

Anti-CarP antibodies as promising marker to measure joint damage and disease activity in patients with rheumatoid arthritis.

Anti-citrullinated protein antibodies (ACPA) are important serological markers in the diagnosis of rheumatoid arthritis (RA) and are part of the recent disease classification criteria. However, there is a strong need for reliable markers for measuring and predicting joint damage and disease activity. Recently, antibodies directed against carbamylated antigens (anti-CarP antibodies) were identified. A total of 120 RA patients were tested for anti-CCP antibodies using different methods and for anti-CarP antibodies using carbamylated fetal calf serum according to the method described by Shi et al. Additionally, ACPA fine specificities (to three citrullinated peptides) were measured. Disease activity was assessed at baseline using the disease activity score 28 (DAS28) in 80 patients. For 40 RA patients, joint erosion score (JES) was established. The median JES was 14.1 with a standard deviation of 11.5. Anti-CarP antibodies were correlated with joint erosion score (ρ = 0.34, 95% CI 0.03-0.59; p = 0.0332). No correlation between ACPA and joint erosion score was observed. No individual marker correlated with DAS28. When one ACPA peptide was combined with anti-CarP antibodies in a score (ACPA peptide 1 divided by anti-CarP), a statistically relevant correlation was found (p = 0.0264). In this small cohort, the presence of anti-CarP antibodies, but not ACPA correlate with joint erosion score. Anti-CarP antibodies combined with ACPA fine specificities correlated with DAS28. Therefore, anti-CarP antibodies might represent a promising marker to predict joint damage and disease activity in RA patients.

Clinical evaluation of a novel chemiluminescent immunoassay for the detection of anti-citrullinated peptide antibodies.

BACKGROUND: We evaluated the analytical and clinical performances of a novel, automated chemiluminescent immunoassay in comparison with several anti-citrullinated protein antibody (ACPA) assays (2nd and 3rd generations) based on various platforms and technologies. METHODS: Samples from rheumatoid arthritis (RA) patients (n=141) and controls (n=153) were collected based on an ordered ACPA test. All samples were tested with QUANTA Flash® CCP3, QUANTA Lite® CCP3, QUANTA Lite® CCP3.1, CCPlus and EliA® CCP assays. Rheumatoid factor (RF) was determined using Quantex RF(II). An additional cohort consisting of RA patients from three different sources (116, 79 and 50 samples), 61 juvenile idiopathic arthritis (JIA) patients and 233 controls were used in an extended evaluation on QUANTA Flash® CCP3 only. Precision and linearity of the QUANTA Flash® CCP3 were assessed according to CLSI guidelines. RESULTS: All ACPA assays showed good qualitative and quantitative agreements. The Quanta Flash CCP3 assay showed good analytical and clinical performance. Based on the extended cohort, the sensitivity, specificity and likelihood ratios of the novel Quanta Flash® CCP3 were defined as 70.2%, 97.4% and 27.3/0.31, respectively. CONCLUSION: Good agreements between different ACPA assays based on diverse platforms were found. Quanta Flash CCP3 is a reliable test for the fully automated and rapid detection of ACPA.

Novel clinical and diagnostic aspects of antineutrophil cytoplasmic antibodies.

Antineutrophil cytoplasmic antibodies (ANCA) are the serological hallmark of some idiopathic systemic vasculitides. Besides the investigation of ANCA-associated vasculitis (AAV) and constant effort for a standardized nomenclature and classification of the AAV, a main focus of research during the last few years has been to constantly improve the performance of enzyme immunoassays. With the latest so called third generation ELISA, this goal seemed to be fulfilled. The International Consensus Statement on Testing and Reporting of ANCA gave recommendations for standardized strategies for the serological diagnosis of ANCA. New developments now target the system immanent drawbacks of the respective diagnostic methods, be it the need for batching and the long time to result for ELISA, or the high likelihood of error and subjectivity of indirect immunofluorescence (IIF). Random access technology and multiplexing for solid phase assays as well as digital imaging for IIF are tools which may help to expedite and simplify routine diagnostics in the lab and in emergency settings. Recent findings indicate that PR3-ANCA have clinical utility beyond the diagnosis of AAV. PR3-ANCA can also serve as an aid for the differentiation between ulcerative colitis (UC) and Crohn's disease (CrD) and the stratification of UC patients. This review provides a detailed review of what is known about ANCA and highlights the latest research and state-of-the-art developments in this area.

Anti-nuclear antibody screening using HEp-2 cells.

The American College of Rheumatology position statement on ANA testing stipulates the use of IIF as the gold standard method for ANA screening(1). Although IIF is an excellent screening test in expert hands, the technical difficulties of processing and reading IIF slides--such as the labor intensive slide processing, manual reading, the need for experienced, trained technologists and the use of dark room--make the IIF method difficult to fit in the workflow of modern, automated laboratories. The first and crucial step towards high quality ANA screening is careful slide processing. This procedure is labor intensive, and requires full understanding of the process, as well as attention to details and experience. Slide reading is performed by fluorescent microscopy in dark rooms, and is done by trained technologists who are familiar with the various patterns, in the context of cell cycle and the morphology of interphase and dividing cells. Provided that IIF is the first line screening tool for SARD, understanding the steps to correctly perform this technique is critical. Recently, digital imaging systems have been developed for the automated reading of IIF slides. These systems, such as the NOVA View Automated Fluorescent Microscope, are designed to streamline the routine IIF workflow. NOVA View acquires and stores high resolution digital images of the wells, thereby separating image acquisition from interpretation; images are viewed an interpreted on high resolution computer monitors. It stores images for future reference and supports the operator's interpretation by providing fluorescent light intensity data on the images. It also preliminarily categorizes results as positive or negative, and provides pattern recognition for positive samples. In summary, it eliminates the need for darkroom, and automates and streamlines the IIF reading/interpretation workflow. Most importantly, it increases consistency between readers and readings. Moreover, with the use of barcoded slides, transcription errors are eliminated by providing sample traceability and positive patient identification. This results in increased patient data integrity and safety. The overall goal of this video is to demonstrate the IIF procedure, including slide processing, identification of common IIF patterns, and the introduction of new advancements to simplify and harmonize this technique.

14th International Congress on Antiphospholipid Antibodies Task Force. Report on antiphospholipid syndrome laboratory diagnostics and trends.

Current classification criteria for definite Antiphospholipid Syndrome (APS) require the use of three laboratory assays to detect antiphospholipid antibodies (aCL, anti-ß2GPI and LA) in the presence of at least one of the two major clinical manifestations (i.e. thrombosis or pregnancy morbidity) of the syndrome. However, several other autoantibodies shown to be directed to other proteins or their complex with phospholipids have been proposed to be relevant to APS but their clinical utility and their diagnostic value remains elusive. This report summarizes the findings, conclusions and recommendations of the "APS Task Force 3-Laboratory Diagnostics and Trends" meeting that took place during the 14th International Congress on Antiphospholipid Antibodies (APLA 2013, September 18-21, Rio de Janeiro, RJ, Brazil).

Analytical and clinical comparison of two fully automated immunoassay systems for the diagnosis of celiac disease.

OBJECTIVE: Here we compared analytical and clinical performance characteristics of two novel automated assay systems for the detection of celiac disease (CD) specific antibodies: QUANTA Flash (INOVA Diagnostics, Inc.) and EliA (Thermo Scientific). METHODS: A total of 74 biopsy-proven CD patients (2 with IgA deficiency) and 138 controls were tested by both methods. RESULTS: Sensitivities of QUANTA Flash assays ranged from 35.1% to 90.5% and specificities from 96.4% to 99.3%, while sensitivities for EliA assays ranged from 37.8% to 90.5% (equivocal considered positive) and specificities from 97.1% to 100.0%. Good qualitative agreement was found between all assays. Thirty-four (50.0%) of the 68 QUANTA Flash h-tTG IgA positive results were higher than 10 times the upper limit of normal (ULN). In contrast, only 22.8% of the EliA tTG IgA positive samples were >10x ULN. Seventy-three (98.6%) biopsy-proven CD patients were correctly identified with the QUANTA Flash h-tTG IgA+DGP IgG combination, while 64 (86.5%) and 72 (97.3%) (depending on equivocal range) were identified with the same combination of EliA assays. CONCLUSION: The QUANTA Flash CD assays have outstanding clinical performance. Of particular clinical significance, in light of proposals to decrease the absolute necessity of biopsy, was the demonstration that 50% of the QUANTA Flash h-tTG IgA results were >10x ULN.

Standardization of antiphospholipid antibody testing--historical perspectives and ongoing initiatives.

The measurement of antiphospholipid antibodies (aPL) has been an important aspect of antiphospholipid syndrome (APS) characterization since the disease was first described in the 1980s. Despite significant efforts geared toward the standardization of immunoassays that measure anticardiolipin antibodies and anti-ß2-glycoprotein I spanning three decades, there are still reports of significant interassay and interlaboratory variation in the results of these assays. At the recent 13th International Congress on Antiphospholipid Antibodies (APLA 2010, April 13-16, 2010, Galveston, TX), a task force composed of internationally recognized experts in the field of APS was formed to address these issues. In this review, we discuss approaches that have been used in the past to achieve harmonization among aPL immunoassays as well as the ongoing efforts of the APLA task force. Our review also highlights the importance of cutoff determination in aPL assays and the clinical significance of positive aPL results of varying magnitudes.

Clinical performance evaluation of a novel rapid response chemiluminescent immunoassay for the detection of autoantibodies to extractable nuclear antigens.

BACKGROUND: We analyzed the performance of a novel ENA screening chemiluminescent immunoassay (CIA) and the confirmation QUANTA Flash tests. METHODS: Sera (n=1079) from patients referred to a rheumatology clinic were screened by QUANTA Flash ENA7 (INOVA Diagnostics). All positive (n=89) and a matched control group (n=90) were reflexed for autoantibodies to the individual antigens. Moreover, sera from patients with systemic lupus erythematosus (SLE, n=252), systemic sclerosis (SSc, n=64), polymyositis/dermatomyositis (PM/DM, n=72), Sjögren's syndrome (SjS, n=39) as well as disease controls (n=605) were tested by ENA7 CIA and by Quanta Lite ENA6 ELISA (INOVA). RESULTS: 89/1079 (8.3%) samples were ENA7 CIA positive with the following reactivity profile: RNP (36.0%), Sm (13.5%), Scl-70 (9.0%), Jo-1 (0.0%), Ro60 (44.9%), Ro52 (39.3%) and SS-B (24.7%). In the negative group, the reactivity profile was: RNP (1.1%), Sm (1.1%), Scl-70 (2.2%) and 0.0% for Jo-1, Ro60, Ro52 and SS-B. The positive/negative/total agreements (ENA7 CIA vs. confirmation assays) were 95.3%/91.5%/93.3%. The sensitivity of the ENA7 CIA was 62.3% in SLE, 54.7% in SSc, 92.3% in SjS, 50.0% in PM/DM, and 61.8% in the total systemic autoimmune rheumatic disease (SARD) population (specificity 95.0%). CONCLUSION: The QUANTA Flash ENA7 CIA is a reliable screening test.

Superior performance of the CCP3.1 test compared to CCP2 and MCV in the rheumatoid factor-negative RA population.

Anti-citrullinated protein/peptide antibodies (ACPAs) have recently been identified as sensitive and specific diagnostic and prognostic markers in rheumatoid arthritis (RA). In this study, we wished to assess the diagnostic performance of the third-generation anti-CCP3.1 assay, but with special focus on the rheumatoid factor (RF)-negative RA population. Anti-CCP as well as anti-MCV was tested in 119 RA patients and 118 control patients using second and third-generation assays. Using these optimal cut-off levels, the diagnostic sensitivity of anti-CCP2, CCP3, and CCP3.1 was 74.8, 78.8, and 83.0%, respectively, while the specificity was 95.7, 96.6, and 98.3%, respectively. The diagnostic performance of the CCP3.1 test was significantly better than that of CCP2 (p = 0.041). In addition, the CCP3.1 test performed significantly better than the MCV test as well (p = 0.0003). When the diagnostic performance of the CCP3.1, CCP2, and MCV tests was compared in the 35 RF-negative patients, the CCP3.1 test exerted significantly better performance than the MCV test (p = 0.006), and it also showed a tendency of better performance in comparison with the CCP2 test (p = 0.131). In conclusion, the CCP3.1 assay can significantly increase the sensitivity of ACPA testing in RF-negative RA, as well as in the total RA population.

Interference in antiphospholipid antibody assays.

Antiphospholipid antibodies (aPL) are detected with two types of laboratory tests: first, antigen-specific immunoassays for the determination of antibodies against cardiolipin, ß2-glycoprotein I and other phospholipids, and phospholipid-protein complexes; second, functional (coagulation) assays for the detection of lupus anticoagulants. Both aPL immunoassays and coagulation assays are prone to interferences, and clinicians need to be aware of the limitations of these assays. Interference is a clinically significant bias in the measured analyte concentration due to the effect of another component or property of the sample. Besides immune-mediated interferences (such as heterophile or human anti-animal antibodies, rheumatoid factor, high immunoglobulin levels, or factor inhibitors), aPL assays are uniquely affected by anticoagulants and the presence of residual platelets in test plasma. Interferences are usually analyte- and assay-specific and may go unrecognized in routine laboratory practice. Despite advances in our knowledge on the mechanisms of interferences in aPL assays, it is unlikely that total elimination will be possible.