Longitudinal Qualitative and Quantitative Evaluation of SARS-CoV-2 Antibodies in Immunized Health Care Workers.

CONTEXT.­: Many studies have depended on qualitative antibody assays to investigate questions related to COVID-19 infection, vaccination, and treatment. OBJECTIVE.­: To evaluate immunoglobulin G (IgG) levels in vaccinated individuals over time and characterize limitations of qualitative and quantitative antibody assays. DESIGN.­: Longitudinal serum samples (n = 339) were collected from 72 health care workers vaccinated against COVID-19. SARS-CoV-2 IgG levels before, during, and after vaccination were measured by using a qualitative anti-spike protein IgG assay and a quantitative anti-S1 IgG assay. Assay results were compared to understand antibody dynamics related to vaccination. RESULTS.­: Qualitative testing demonstrated 100% seroconversion after the first vaccine dose, peak IgG levels after the second vaccine dose, and a progressive 50% decline during the next 8 months. Quantitative testing demonstrated that IgG levels during and after vaccination were above the analytical measurement range. CONCLUSIONS.­: Qualitative testing demonstrates expected changes in SARS-CoV-2 IgG levels related to sequential vaccine doses and time since antigen exposure. However, proportional changes in the associated numerical signals are very likely inaccurate. Adoption of standardized quantitative SARS-CoV-2 antibody testing with a broad analytical measurement range is essential to determine a correlate of protection from COVID-19 that can be scaled for widespread use.

Prenatal serum screening for Down syndrome and neural tube defects in the United States: Changes in utilization patterns from 2012 to 2020.

OBJECTIVE: To compile current usage of serum-based prenatal screening for Down syndrome in the United States and compare it with results from a similar 2011/2012 survey. SETTING: The College of American Pathologists maternal screening proficiency testing survey includes a supplemental question on the first of three yearly distributions. METHODS: Information regarding tests offered and the monthly number of pregnancies tested for US-based laboratories were reviewed. Results were stratified by size of laboratory, tests offered, and pregnancies tested. Findings were compared to an earlier survey. RESULTS: Fifty-six laboratories reported they will have screened 1,131,336 pregnancies in 2020. Of these, 36% are screened by stand-alone first trimester testing, 48% by stand-alone second trimester testing, and 16% using tests that integrate results from both trimesters. Eighty percent of all serum screens were provided by the five laboratories that performed the most screens (at least 50,000). These five performed similar proportions of first or second trimester screens (42.2% and 41.8%, respectively). Compared to eight years earlier, there are now 54% fewer laboratories. Pregnancies screened using the first trimester, second trimester, and integrated protocols were lower by 27%, 69%, and 72%, respectively. The serum screening activity in the US showed a 62% decrease from 2012 levels. During 2012-2020, the number of cell-free DNA tests increased from negligible to 1,492,332. CONCLUSIONS: Maternal serum screening for common aneuploidies has changed significantly in eight years with fewer laboratories, a shift toward larger laboratories and a 2.5-fold reduction in pregnancies tested, likely due to the introduction of cell-free DNA screening.

Assessment of laboratories offering cell-free (cf) DNA screening for Down syndrome: results of the 2018 College of American Pathology External Educational Exercises.

PURPOSE: Summarize and interpret results from exercises distributed to laboratories offering cell-free (cf) DNA screening for Down syndrome. METHODS: The College of American Pathologists distributed three patient-derived plasma specimens twice in 2018. Sequencing platforms, test methods, results, and responses to supplemental questions were collected. Results were not graded but discrepancies were identified. RESULTS: Sixty-five laboratories from six continents enrolled; six provided no results. The most common methodology was shotgun/genome sequencing (39/56, 70%). Overall, 40% of the gestational or maternal age responses were incorrect but 45% of the errors were corrected by the next distribution. Fetal fractions from 54 responding laboratories generally agreed with the intended response. No genotyping errors occurred (40/40 for trisomy 21 and 226/226 for euploid challenges) but 10 additional tests failed (3.6%). All 213 fetal sex calls were correct. Participants reported their clinical text for a Down syndrome screen positive test; 39% were classified as inadequate or misleading. CONCLUSION: Patient-derived materials are suitable for all enrolled technologies/methodologies, but collecting material is challenging. Suggested clinical text includes the terms "screen positive" and "screen negative." Overall, laboratories performed well. Future efforts will focus on potential manufactured samples, clarifying results reporting and including additional chromosome abnormalities.

The Case for Laboratory Developed Procedures: Quality and Positive Impact on Patient Care.

An explosion of knowledge and technology is revolutionizing medicine and patient care. Novel testing must be brought to the clinic with safety and accuracy, but also in a timely and cost-effective manner, so that patients can benefit and laboratories can offer testing consistent with current guidelines. Under the oversight provided by the Clinical Laboratory Improvement Amendments, laboratories have been able to develop and optimize laboratory procedures for use in-house. Quality improvement programs, interlaboratory comparisons, and the ability of laboratories to adjust assays as needed to improve results, utilize new sample types, or incorporate new mutations, information, or technologies are positive aspects of Clinical Laboratory Improvement Amendments oversight of laboratory-developed procedures. Laboratories have a long history of successful service to patients operating under Clinical Laboratory Improvement Amendments. A series of detailed clinical examples illustrating the quality and positive impact of laboratory-developed procedures on patient care is provided. These examples also demonstrate how Clinical Laboratory Improvement Amendments oversight ensures accurate, reliable, and reproducible testing in clinical laboratories.

A Cost-Effectiveness Analysis of First Trimester Non-Invasive Prenatal Screening for Fetal Trisomies in the United States.

BACKGROUND: Non-invasive prenatal testing (NIPT) is a relatively new technology for diagnosis of fetal aneuploidies. NIPT is more accurate than conventional maternal serum screening (MSS) but is also more costly. Contingent NIPT may provide a cost-effective alternative to universal NIPT screening. Contingent screening used a two-stage process in which risk is assessed by MSS in the first stage and, based on a risk cutoff, high-risk pregnancies are referred for NIPT. The objective of this study was to (1) determine the optimum MSS risk cutoff for contingent NIPT and (2) compare the cost effectiveness of optimized contingent NIPT to universal NIPT and conventional MSS. STUDY DESIGN: Decision-analytic model using micro-simulation and probabilistic sensitivity analysis. We evaluated cost effectiveness from three perspectives: societal, governmental, and payer. RESULTS: From a societal perspective, universal NIPT dominated both contingent NIPT and MSS. From a government and payer perspective, contingent NIPT dominated MSS. Compared to contingent NIPT, adopting a universal NIPT would cost $203,088 for each additional case detected from a government perspective and $263,922 for each additional case detected from a payer perspective. CONCLUSIONS: From a societal perspective, universal NIPT is a cost-effective alternative to MSS and contingent NIPT. When viewed from narrower perspectives, contingent NIPT is less costly than universal NIPT and provides a cost-effective alternative to MSS.

Is maternal plasma DNA testing impacting serum-based screening for aneuploidy in the United States?

PURPOSE: We sought to determine whether tests for fetal aneuploidy based on next-generation sequencing of cell-free DNA in maternal circulation have had an impact on routine serum-based screening in the general pregnant population. METHODS: We compared results from laboratory surveys in 2011 and 2014 that reported types of prenatal serum screening tests and numbers of tests performed. Testing records from two prenatal serum screening laboratories examined temporal trends in the proportion of screened women 35 years of age and older from 2008 (or 2009) to 2014. RESULTS: The 82 laboratory survey results available for comparison showed that 1.7 million women were screened in 2014, a 5% increase over 2011. In the two screening laboratories, the proportion of screened women age 35 and older increased for several years but then experienced reductions of 8 and 18% by mid-2014 when compared with the highest rates observed. CONCLUSION: As of 2014, maternal plasma DNA testing appears to have had only a minor impact on serum screening rates in the United States. Ongoing surveillance has the potential to determine if, and when, DNA testing begins to replace serum testing as a primary screen for Down syndrome in the United States.

A cost-effectiveness analysis of cell free DNA as a replacement for serum screening for Down syndrome.

OBJECTIVE: The aim of this article is to determine the cost effectiveness of cell free DNA (cfDNA) as a replacement for integrated screening using a societal cost perspective. METHOD: This study used Monte-Carlo simulation with one-way and probabilistic sensitivity analysis. RESULTS: Cell free DNA is more effective and less costly than integrated screening. The incremental cost-effectiveness ratio for cfDNA relative to the integrated test was -$277 955 per case detected (95th percent confidence interval -$881 882 to $532 785). CONCLUSION: Cell free DNA screening is a cost-effective replacement for maternal serum screening when the lifetime costs of Down syndrome live births are considered. The adoption of cfDNA screening would save approximately $277 955 for each additional case detected over integrated screening.

An analysis of clinical consultation activities in clinical chemistry: implications for transformation and resident training in chemical pathology.

CONTEXT: Clinical consultation is a key role of pathologists. Many have advocated that pathologists expand their consulting activities to improve laboratory utilization. Although many have suggested that residency programs need to provide experience in clinical consultation, little has been written on the nature of consultation or on the methods of training. OBJECTIVE: To characterize the content of consultations and to describe training in consultation in chemical pathology within the residency program at the University of Utah, Salt Lake City. DESIGN: Retrospective review of the consultation database for the period between July 2011 and July 2012. RESULTS: Residents performed an average of 159 consultations a month covering 276 topics during the course of a year. Each topic involved 1 or more specific tests. Eighty percent of the topics received fewer than 12 calls. The most common topics involved virus testing (eg, hepatitis B virus, hepatitis C virus, human immunodeficiency virus). Consultations most often involved test interpretation (53%), selection (38%), and performance characteristics (21%). Twenty-seven percent of consultations involved 2 or more consultation categories (eg, interpretation and performance). CONCLUSIONS: Consultation calls in chemical pathology are widely distributed across topics. Consultations most often involve test interpretation and selection. Methods to assess the effectiveness of consultations and resident teaching should be devised.

A tradeoff analysis of risk cutoffs for the quadruple serum screen for Down syndrome.

OBJECTIVES: In maternal serum screening for Down syndrome, a cutoff of 1 : 270 is often used as a decision point to recommend invasive confirmatory testing. However, it has not been established how well this or any other cutoff relates to patient preferences, that is, the values that pregnant women attach to various screening outcomes. The purpose of this study was to examine the clinical and economic tradeoffs of a wide range of risk cutoffs for the quadruple screen. METHODS: Screening costs and outcomes for multiple risk cutoffs were modeled using a Monte Carlo simulation. RESULTS: The optimal cutoff for maternal serum screening depends on the relative values placed by the patient on different outcomes. Total societal costs were similar across the range of cutoffs. CONCLUSIONS: Given that different screening outcomes are optimized by different cutoff values, a one-size-fits-all approach may not be appropriate.

Screening for down syndrome in the United States: results of surveys in 2011 and 2012.

CONTEXT: Participants in a College of American Pathologists external proficiency testing program for first and second trimester Down syndrome screening. OBJECTIVES: To determine the number of women screened for Down syndrome in the United States, along with the type of test received and to compare those results to earlier surveys in 1988 and 1992. DESIGN: Questionnaires regarding the type and number of Down syndrome tests performed per month were completed by participants in early 2011 and again in early 2012. RESULTS: After accounting for some of the missing responses, data from up to 131 laboratories indicated that 67% (2 764 020 of 4 130 000) to 72% (2012: 2 963 592 of 4 130 000) of US pregnancies received prenatal screening for Down syndrome. Second trimester tests were most common (2012: 60%; 1 770 024 of 2 963 592), followed by integrated (2012: 21%; 627 876 of 2 963 592), and first trimester (2012: 19%; 565 692 of 2 963 592). The 6 largest laboratories tested 61% of screened pregnancies and offered the widest array of tests, while the smallest 32 tested 1% and almost always offered only second trimester tests. CONCLUSIONS: The current population estimate of 72% pregnancies screened annually is higher than estimates from 1988 (25%) and 1992 (50%). Available testing choices are also more varied, and all testing methods perform better than those methods available 10 years ago. Clinicians should ensure that women are offered tests that follow recommended best-practice testing protocols, and screening laboratories should assess whether patient needs are being met.

α1-Antitrypsin phenotypes and associated serum protein concentrations in a large clinical population.

BACKGROUND: α1-Antitrypsin (AAT) deficiency variants reduce the concentration of serum AAT protease inhibitor and can lead to the development of pulmonary and hepatic disease. Relative frequencies of rare AAT variant phenotypes (non-M, Z, and S) and associated serum concentrations in the clinical population have not been thoroughly described. METHODS: Protein phenotypes were determined by isoelectric focusing electrophoresis for 72,229 consecutive samples. Phenotype frequencies, median serum concentrations, and central 95% concentration intervals were determined for observed phenotypes. Concurrent AAT phenotype and concentration data were used to evaluate the efficacy of using serum AAT concentration alone to detect AAT deficiency. RESULTS: Age, race, and sex had only slight effects on the median 95% serum protein concentration intervals of the 58,087 PiMM (wild type) phenotype specimens. Positive predictive values were calculated for the detection of potential deficiency phenotypes at different serum cutoff concentrations, aiding potential screening effort design. For example, the PiZZ deficiency phenotype (n = 814) could be detected at 99.5% sensitivity and 96.5% specificity using a cutoff of ≤ 85 mg/dL. However, at-risk specimens with two putative deleterious variants (Z, S, I, F, P, T, and Null variants) were detected with only 85.9% sensitivity at this cutoff (n = 1,661). Rare phenotype variants were observed in 2.5% of samples. CONCLUSIONS: This analysis provides novel information on serum AAT concentrations associated with different AAT phenotypes and provides insight into the severity of depression of AAT concentration in the presence of rare deficiency variants. Additionally, it allows for evaluation of efficacy of testing algorithms incorporating AAT serum concentration determination.

Recent trends in performance and current state of creatinine assays.

CONTEXT: Measured plasma or serum creatinine concentration is a primary component of equations used to calculate estimated glomerular filtration rate (eGFR). In recent years, most assay manufacturers have adopted creatinine calibration procedures that are traceable to the National Institute of Standards and Technology's Standard Reference Material 967. OBJECTIVES: To examine the current performance of creatinine assays, to compare changes in assay performance since 2003, and to examine the reliability of laboratory eGFR calculations. DESIGN: Serum samples spiked with different concentrations of creatinine were analyzed by participating laboratories in the College of American Pathologists' LN24 survey. Participants' reported values were compared against values measured by liquid chromatography-isotope dilution mass spectrometry. Participants were asked to calculate the eGFR for certain samples, and results were compared with those obtained from the 4-parameter Modification of Diet in Renal Disease equation. RESULTS: Biases among current creatinine methods are in the range of -5% to 10%, compared with -7% to 34% seen in a 2003 study. This degree of bias in eGFR calculations is of clinical significance only for concentrations near the cut points used to stage chronic kidney disease. Approximately 20% of laboratories report eGFR values that exceed ±1 mL/min per 1.73 m(2) from the expected eGFR using the 4-parameter Modification of Diet in Renal Disease equation. CONCLUSIONS: Since 2003, there have been improvements in the performance of creatinine assays, which appear to be related to the adoption of standard reference materials for calibration. The effect of the observed method biases in clinical practice now appears minimal. Laboratories should continue to monitor the accuracy of eGFR calculations.

Identification of histoplasma-specific peptides in human urine.

Histoplasmosis is a severe dimorphic fungus infection, which is often difficult to diagnose due to similarity in symptoms to other diseases and lack of specific diagnostic tests. Urine samples from histoplasma-antigen-positive patients and appropriate controls were prepared using various sample preparation strategies including immunoenrichment, ultrafiltration, high-abundant protein depletion, deglycosylation, reverse-phase fractions, and digest using various enzymes. Samples were then analyzed by nanospray tandem mass spectrometry. Accurate mass TOF scans underwent molecular feature extraction and statistical analysis for unique disease makers, and acquired MS/MS data were searched against known human and histoplasma proteins. In human urine, some 52 peptides from 37 Histoplasma proteins were identified with high confidence. This is the first report of identification of a large number of Histoplasma-specific peptides from immunoassay-positive patient samples using tandem mass spectrometry and bioinformatics techniques. These findings may lead to novel diagnostic markers for histoplasmosis in human urine.

Exploratory study of proteins in urine of patients with histoplasma antigenuria.

Disseminated histoplasmosis is an invasive fungal infection that can be fatal in patients with weak immune system. The goal of our exploratory study was to evaluate differences in urinary protein profiles among samples of healthy individuals, patients with proteinuria (PRU), and histoplasma antigenuria (HIS), and to identify physiological pathways associated with the excreted proteins. Urine samples were depleted of abundant proteins, deglycosylated, digested with trypsin, fractionated and analyzed by nano-LC-QTOF. The total number of human proteins identified in the samples was 117, of which 20 and 23 were unique to the samples from patients with PRU and HIS, respectively. Pathway analysis of proteins identified in samples of PRU and HIS patients suggested increased levels of proteins associated with acute response signaling, coagulation system, prothrombin activation, glucocorticoid regulation and the lipid antigen presentation signaling pathway networks. The obtained data provide information on protein expression associated with HIS, and suggest that further more rigorous studies aimed at the identification of proteins associated with proteinuria of different causes are feasible.