Background:Many tree pollens are associated with the pathogenesis of allergic disease. Objective:Our aim was to investigate prevalence, risk factors, and geographic variation of tree pollen sensitization in the United States. Methods:Results of specific IgE testing for pollen of 31 tree species were obtained from a single United States-wide clinical laboratory by physicians' requests submitted in 2014-2023. Tree pollen sensitization data were statistically analyzed with respect to prevalence, patterns, and relationship with demographic characteristics, clinical diagnoses, and geographic regions. Results:A total of 23,932,544 specific IgE tests, originating from 3,067,173 unique patients ranging in age from 0 to 85 years were identified. Males showed higher positivity rates across all tree species and age groups. In both sexes, positivity was highest in individuals aged 10 to 19 years and in patients with atopic dermatitis and asthma. Patients living in urban areas had higher rates of sensitization than patients in rural areas. Considerable differences in top sensitizers were identified across ecoregions, even among different ecoregions present within the same US state. Rates of cosensitization to allergen pairs were generally associated with phylogenetic proximity of species. Conclusion:Factors associated with higher rates of tree pollen sensitization included being male, being a teenager, having atopic dermatitis, having asthma, and living in a specific ecologic region. Results from this study may be helpful to clinicians in counseling patients, as well as to laboratories designing geographically based allergen testing panels.

This study presents the automation of the pooled donor basophil activation test (PD-BAT) for chronic urticaria, transitioning from a previously published manual assay in tubes to an automated 96-well plate format using the Hamilton Microlab STAR system. The primary aim is to enhance throughput and robustness in a commercial lab environment while maintaining assay accuracy and reproducibility. Donor screening included 36 individuals, of which 16 were selected for pooled assays. A total of 90 sera were analyzed in parallel by manual and automated methods. The automated PD-BAT demonstrated 93.3% qualitative agreement (r > 0.97) with the manual assay. Throughput improved through automation, a 66% reduction in hands-on time was observed between the manual (9 h/batch) and automated (3 h/batch) methods. Discordant results (6.7%) occurred only near the technical cutoff, highlighting both the robustness and limitations of the method. This automation represents a valuable advancement over the manual assay, optimizing laboratory workflows.

To provide an accessible and clinically viable plasma panel to assist physicians with the diagnosis of Alzheimer's disease (AD).

Objectives: The direct approach for determining reference intervals (RIs) is not always practical. This study aimed to generate evidence that a real-world data (RWD) approach could be applied to transfer free thyroxine RIs determined in one population to a second population, presenting an alternative to performing multiple RI determinations. Design and methods: Two datasets (US, n = 10,000; Europe, n = 10,000) were created from existing RWD. Descriptive statistics, density plots and cumulative distributions were produced for each data set and comparisons made. Cumulative probabilities at the lower and upper limits of the RIs were identified using an empirical cumulative distribution function. According to these probabilities, estimated percentiles for each dataset and estimated differences between the two sets of percentiles were obtained by case resampling bootstrapping. The estimated differences were then evaluated against a pre-determined acceptance criterion of <= 7.8% (inter-individual biological variability). The direct approach was used to validate the RWD approach. Results: The RWD approach provided similar descriptive statistics for both populations (mean: US = 16.1 pmol/L, Europe = 16.4 pmol/L; median: US = 15.4 pmol/L, Europe = 15.8 pmol/L). Differences between the estimated percentiles at the upper and lower limits of the RIs fulfilled the pre-determined acceptance criterion and the density plots and cumulative distributions demonstrated population homogeneity. Similar RI distributions were observed using the direct approach. Conclusions: This study provides evidence that a RWD approach can be used to transfer RIs determined in one population to another.

The type II autoimmune subtype of Chronic Spontaneous Urticaria (CSU) is characterized by the presence of IgG autoantibodies targeting IgE or the IgE high-affinity receptor (FcεRI) on mast cells and basophils. In evaluation of CSU patients, indirect basophil activation testing (BAT), has been utilized, involving the mixing of patient serum with heterologous peripheral blood donors, followed by flow cytometric assessment of basophil markers. However, the reliability of the indirect BAT results hinges on the quality of the donor basophils utilized. In this study, we introduce an innovative approach where multiple potential basophil donors undergo rigorous BAT characterization alongside control samples. By selecting and pooling donors with optimal performance, we significantly enhance the inter-assay reproducibility of the indirect BAT test.

Importance: With the emergence of new therapeutics for treatment of Alzheimer's disease, there is currently a critical need for sensitive and accurate blood-based tests to assist with the diagnosis and treatment of Alzheimer's disease. Objective: To determine the clinical validity of an analytically validated plasma panel for the assessment of Alzheimer's disease. Design, Setting, and Participants: This cross-sectional study measured biomarkers representative of the Alzheimer's disease AT(N) framework in 200 plasma specimens acquired from the Australian Imaging, Biomarker & Lifestyle (AIBL) Study of Ageing. Specimens were obtained from amyloid PET negative subjects classified as cognitively unimpaired (n = 75) and amyloid PET positive subjects classified as having no cognitive impairment (n = 49), mild cognitive impairment (n = 26), or Alzheimer's disease dementia (n = 50). Exposures: Amyloid PET and plasma Aβ42/40, pTau181, and NfL. Main Outcomes and Measures: To assess the utility of the plasma panel to assess onset and progression of Alzheimer's disease with respect to amyloid PET results and cognitive impairment. Results: A difference was observed for each assay with respect to amyloid status (p<0.0001). Receiver operating characteristic (ROC) analysis of clinical specimen results from validated assays produced an area-under-the-curve (AUC) of 0.941 for Aβ42/40, 0.847 for pTau181, and 0.666 for NfL (p < 0.0001 for all biomarkers). The sensitivity (96.0%) and specificity (86.7%) observed for Aβ42/40 measurements meets current recommendations for triage testing. In addition, plasma levels of pTau181 and NfL were also found to increase with worsening cognitive impairment. Conclusions and Relevance: The clinical concordance with amyloid PET for each biomarker is consistent with the biological progression of the AD continuum. As such, the availability of this AT(N) panel will provide clinicians with a simple blood-based means to provide evidence of AD pathological changes and could help identify AD patients much faster, shorten the overall AD patient diagnostic journey, and enable earlier treatment interventions. ### Competing Interest Statement BBC, MRC, WCB, TL, ABH, JMV, RM, JWW, DB, AV, and RPG are employees of Labcorp and all participate in the employee stock purchase plan. ### Funding Statement This study did not receive any external funding. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ethics committees of Austin Health, St Vincent's Health, Hollywood Private Hospital, and Edith Cowan University approved of the Australian Imaging, Biomarker & Lifestyle (AIBL) Study of Ageing from which clinical specimens were acquired. Additional clinical specimens were purchased from ProteoGenex (Inglewood, CA) which were collected under ethical regulations and in accordance all applicable (local and international) laws (https://www.proteogenex.com/about-us/ethics-policy/). In addition, samples were collected internally from subjects that self-reported as healthy. These samples were collected under an IRB approved protocol (WCG IRB protocol #520100174). In all cases, informed consent was obtained from subjects prior to specimen collection. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data discussed are contained within the manuscript or the supplemental information.

Objective: To validate a neurofilament light chain (NfL) assay on a clinical autoanalyzer to enable clinical utility for a broad range of neurogenerative diseases and conditions. Background: NfL has been demonstrated to become elevated in serum as a result of several neurodegenerative diseases including MS, Alzheimer's disease, ALS, Parkinson's disease, and Huntington disease. Measurements of NfL could assist with monitoring disease treatment as well as recovery from traumatic brain injuries such as concussions. This work details the exhaustive LDT assay validation performed at Labcorp for the measurement of NfL in serum and plasma using the Roche cobas® autoanalyzer platform. This assay does not currently have regulatory approval. Design/Methods: Assay validation studies investigating instrument carryover, blood matrix interferences, alternate specimen types, matrix mixing, lower limit of quantitation, analytical measurement range, and accuracy. Comparison to the predicate assay from Quanterix which has primarily been utilized to establish the clinical utility of NfL levels. Additionally, robust reference interval studies were performed to establish and verify normal levels of NfL across several patient age groups. Studies were also performed to determine stability of NfL for a range of specimen types, storage conditions, and operational settings. The stability of assay materials (reagent, calibrators, and controls) was also demonstrated over time periods that would facilitate operational utility. Results: Acceptable assay and sample performance including correlation to a predicate assays was demonstrated preserving the clinical utility of NfL measurements with this assay. Conclusions: The NfL assay is currently available for measurement of patient samples at a Labcorp laboratory. Disclosure: Dr. Collier has received personal compensation for serving as an employee of Labcorp. Dr. Collier has stock in Labcorp. Dr. Valcour has nothing to disclose. Dr. Volpe has received personal compensation for serving as an employee of Labcorp. Dr. Grant has received personal compensation for serving as an employee of Labcorp.

Background: Understanding how allergies to 1 environmental fungus can lead to cosensitization to related fungi is important for the clinical management of allergies. Cosensitization can be caused by monosensitization combined with antibody cross-reactivity, or by coexposures driving independent sensitizations. A pioneering study showed that patterns of IgE cosensitization among 17 fungal species mirror fungal phylogeny. This could reflect either epitope or habitat similarity. Thanks to an improved understanding of fungal phylogeny, larger serologic testing datasets, and environmental data on household fungi, we can now characterize the relationship between cosensitization, species similarity, and likely coexposure with greater precision. Objective: To assess the degree to which IgE cosensitization in a group of 17 fungi can be attributed to species similarity or environmental coexposure. Methods: Cosensitization patterns among 17 fungal species were estimated from a dataset of approximately 8 million serologic tests on 1.6 million patients. Linear regression of cosensitization on phylogenetic distance and imputed coexposure was performed. In addition, branch lengths for the phylogenetic tree were re-estimated on the basis of cosensitization and compared with corresponding phylogenetic branch lengths. Results: Phylogenetic distance explains much of the observed cosensitization (adjusted r2 = .68, p < .001). Imputed environmental coexposures and test co-ordering patterns do not significantly predict cosensitization. Branch length comparisons between the cosensitization and phylogenetic trees identified several species as less cosensitizing than phylogenetic distance predicts. Conclusion: Combined evidence from clinical IgE testing data on fungi, along with phylogenetic and environmental exposure data, supports the hypothesis that cosensitization is caused primarily by monosensitization plus cross-reactivity, rather than multisensitization. A serologic test result should be interpreted as pointing to a group of related species that include the sensitizing agent rather than as uniquely identifying the agent. The identified patterns of cross-reactivity may help optimize test panel design. (c) 2023 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. This is an open access article under the CC BY -NC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Objective: Develop and validate paraneoplastic syndrome and other autoimmune neurological tests and panels based on Paraneoplastic Syndrome (PNS)-Care panel recommendations and phenotype-based focus. Background: Autoantibody testing for neurological diseases such as paraneoplastic disorders, encephalopathies, and myelopathies has become increasingly complex over time due to the discovery of new biomarkers. The growing number of options for antibody panel testing can create confusion amongst ordering clinicians and lead to either ordering concurrently several overlapping panels or repeat panel evaluations. There is an urgent need for the development and standardization of neurological autoimmune and paraneoplastic autoantibody testing based on new practice standards and phenotype-based selection. Design/Methods: We designed and validated a comprehensive paraneoplastic profile that included a combination of high-, intermediate- and low-probability antibodies associated with cancer. A "catch-all algorithm" consisting of 25 antibody markers was designed for the situation when a clear clinical presentation is absent, but a neurological condition associated with a neoplasm is suspected. A phenotype-based algorithm was designed by choosing neurological condition-specific markers and the appropriate methods for optimal sensitivity and specificity. A combination of assay methods such as immunofluorescence on multiple neural and non-neural tissue substrates, immunofluorescence on HEK293 target transfected substrate, enzyme immunoassay, radioimmunoassay, and line blot assay was used to design testing profiles suitable for different autoimmune neurological conditions. Results: A comprehensive autoimmune neurology/paraneoplastic profile was developed and validated for testing of the patients in a large national reference laboratory. Other phenotype-specific profiles were also validated for autoimmune conditions such as encephalopathy, epilepsy, rapid onset dementia, axonal neuropathy, and myelopathy. A follow-up study using these validated tests in our laboratory showed that for the patients who had any reactive autoantibody, the distribution was approximately 25% positive for GAD65, 20% VGKC (LGI1/CASPR2), 15% to NMDAR1, 10% to VGCC and the remaining 30% were reactive for assorted other targets. Conclusions: NA Disclosure: Dr. Grover has nothing to disclose. Dr. Naides has received personal compensation for serving as an employee of Labcorp (Laboratory Corporation of America Holdings). Dr. Naides has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Labcorp (Laboratory Corporation of America Holdings). Dr. Naides has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for EUROIMMUN US. Dr. Naides has received personal compensation in the range of $0-$499 for serving as a Consultant for Guidepoint. Dr. Naides has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Applied Biocode. Dr. Naides has received personal compensation in the range of $0-$499 for serving as a Consultant for GLG. Dr. Naides has received personal compensation in the range of $0-$499 for serving as a Consultant for Invetech. Dr. Naides has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Alphasights. Dr. Naides has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Adaptive Biotechnologies. Dr. Naides has a non-compensated relationship as a Member, Board of Directors with Autoimmune Encephalitis Alliance that is relevant to AAN interests or activities. Dr. Valcour has nothing to disclose. Dr. Ricchiuti has nothing to disclose. Dr. Nye has nothing to disclose. Dr. Volpe has received personal compensation for serving as an employee of Labcorp.

Background: Many fungal species are associated with the pathogenesis of allergic disease, yet most epidemiologic studies on IgE-mediated fungal sensitization have only included a few species.Objective: We investigated fungal allergen sensitization prevalence, risk factors, and geographic variation in the United States.Methods: From 2014 to 2019, a total of 7,912,504 serum-specific IgE (sIgE) test results for 17 fungal species were measured in 1,651,203 patients aged 0-85 years by a US-wide clinical laboratory. Fungal sensitization prevalence, patterns, and relationship with demographic characteristics, clinical diagnoses, and geographic regions were analyzed.Results: Twenty-two percent of patients were positive (sIgE > 0.10 kUA/L) to at least 1 fungal allergen; 13.7% were positive to >2 fungal allergens. Fungal species-specific positivity rates ranged 7.4-18.6% and were highest for Candida albicans (18.6%), Alternaria alternata (16.6%), Stemphylium herbarum (14.9%), and Aspergillus fumigatus (14.2%). Other fungi that were frequently tested had relatively low positivity rates (eg, Cladosporium herbarum 11.1%, Penicillium chrysogenum 10.7%). Independent risk factors for test positivity for all fungal species included male sex, teen age (highest in those aged 10-19 years), atopic dermatitis, and asthma. Fungal sensitization was generally higher in urban areas and ecoregions composed predominantly of grasslands and prairies compared to woodlands and forest, although there was greater variation in sensitization risk to different fungi in different ecoregions.Conclusion: Independent risk factors for fungal sensitization include male sex, teen ages, atopic dermatitis, asthma, and ecoregion.

Abstract Context Method-specific reference intervals (RIs) determine utility of IGF-I as a biomarker in GH-related diseases. Differences between populations might affect applicability of RIs. Objective To compare population-specific RIs derived from IGF-I routine testing in laboratories in the United States and Europe using the same assay. Design and setting Uncensored routine IGF-I testing results generated over 5 years in 4 accredited laboratories (US, n = 778 173 males/710 752 females; Europe, n = 23 220 males/40 183 females). Main outcome measures Construction of RIs by indirect statistical methods designed to use routine testing data (modified Hoffmann approach). Comparison to published RIs, between the US and Europe, and between regions in the United States with lower and higher mean body mass indexes (BMIs). Results Lower limits (LLs) of RIs calculated from all routine data sets do not differ from the published LLs. The same is true for upper limits (ULs) calculated from European routine data. ULs derived from US routine data are significantly higher (children, 10-18 years [mean, %]: boys + 149.3 ng/mL [+34.6%]; girls + 94.9 ng/mL [+19.8%]); adults (19-95 years: males + 45 ng/mL [+20.3%]; and females + 29.7 ng/mL [+13.8%]). Average IGF-I is higher in samples from Colorado (lower mean BMI) compared with Alabama (P < 0.0001), although the difference is smaller than between each of them and Europe. Conclusions We provide evidence that in large datasets from the same population, direct sampling and the indirect Hoffmann approach provide comparable RIs. Although LLs are comparable between Europe and the United States, the UL is significantly higher in the United States. We suggest use of adapted RIs for the United States.

Clinical & Experimental AllergyEarly View RESEARCH LETTER A new vicilin-like allergen in hazelnut giving rise to a spectrum of IgE-binding low-molecular-weight N-terminal fragments Lars Mattsson, Lars Mattsson Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorMarie Holmqvist, Marie Holmqvist Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorHelena Porsch, Helena Porsch Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorHåkan Larsson, Håkan Larsson Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorBo Pontoppidan, Bo Pontoppidan Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorAndre Valcour, Andre Valcour Laboratory Corporation of America, Burlington, North Carolina, USASearch for more papers by this authorJonas Lidholm, Corresponding Author Jonas Lidholm jonas.lidholm@thermofisher.com orcid.org/0000-0002-7779-3411 Thermo Fisher Scientific, Uppsala, Sweden Correspondence Jonas Lidholm, Thermo Fisher Scientific, Research & Development, P.O. Box 6460, Uppsala SE-751 37, Sweden. Email: jonas.lidholm@thermofisher.comSearch for more papers by this author Lars Mattsson, Lars Mattsson Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorMarie Holmqvist, Marie Holmqvist Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorHelena Porsch, Helena Porsch Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorHåkan Larsson, Håkan Larsson Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorBo Pontoppidan, Bo Pontoppidan Thermo Fisher Scientific, Uppsala, SwedenSearch for more papers by this authorAndre Valcour, Andre Valcour Laboratory Corporation of America, Burlington, North Carolina, USASearch for more papers by this authorJonas Lidholm, Corresponding Author Jonas Lidholm jonas.lidholm@thermofisher.com orcid.org/0000-0002-7779-3411 Thermo Fisher Scientific, Uppsala, Sweden Correspondence Jonas Lidholm, Thermo Fisher Scientific, Research & Development, P.O. Box 6460, Uppsala SE-751 37, Sweden. Email: jonas.lidholm@thermofisher.comSearch for more papers by this author First published: 19 July 2022 https://doi.org/10.1111/cea.14202Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Early ViewOnline Version of Record before inclusion in an issue RelatedInformation

Understanding of IgE sensitization to fungal allergens in the United States is limited. We investigated IgE sensitization to 17 different fungi in a large-scale nationwide analysis. Serum specific IgE to 17 fungal allergens were collected from a U.S.-wide clinical lab (Labcorp®, Inc.) database of 1,667,874 patients from 2014-2019. Prevalence of fungal sensitization (positive>0.10 kUa/L) and relationship with demographic characteristics and clinical diagnosis (ICD-10 codes) were analyzed using logistic regression and chi-squared. 22.2% of patients were positive for at least one fungal allergen; 13.7% were multi-sensitized (positive to >2 fungal allergens). Positivity rates ranged from 7.3% (Tricoderma viridae) to 18.7% (Candida albicans); median positive rate 12.1%. Males had higher positivity rates than females (p<0.01). Positivity rates were lowest for patients age 0-5 years, highest at 10-19 years, and decreased with increasing age. 41,453 (2.4%), 149,926 (8.6%), 620,900 (35.6%) and 37,253 (2.1%) patients had atopic dermatitis, asthma, allergic rhinitis and sinusitis respectively. Higher positivity rates were found in patients with atopic dermatitis and asthma than rhinitis and sinusitis (34.3, 31.6, 24.4, and 20.1% positive to at least one fungus, respectively). In patients with these diagnoses, the highest positivity rates were to Alternaria alternata, Candida albicans, Aspergillus fumigatus, Saccharomyces cerevisiae and Stemphylium herbarum. In multi-sensitized patients, highest positivity rates were to Alternaria alternata, Aspergillus fumigatus, Cladosporium herbarum, Penicillium chrysogen, and Stemphylium herbarum. Correlation analyses of IgE concentrations showed clustering similar to that predicted by molecular phylogeny. Sensitization to fungal allergens shows significance associations with patient sex, age, and allergic disease.

Data that support the findings of this study are available from the corresponding author upon reasonable request. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Abstract Background: IGF-I is the most widely used biomarker for management of GH related diseases. Reproducible assays and method-specific reference intervals (RIs) are crucial determinants of its clinical utility. Assay validation and RIs based on >15,000 subjects were published for the IDS iSYS IGF-I assay (J Clin Endocrinol Metab 2014). We now analyzed distribution of IGF-I results obtained in routine samples analyzed by accredited laboratories in the US and Europe, all using the IDS iSYS assay. Methods: All results from routine IGF-I measurements during the past 5 years in 4 laboratories were included (US lab n=778,173 males/710,752 females; European labs (Germany/Belgium, n=23,220 males/40,183 females). Assay performance across laboratories was confirmed through proficiency testing schemes and exchange of patient samples. We constructed RIs adjusted for age/sex from European and US cohorts separately using a modified Hoffmann approach (Am J Clin Pathol 2015), and compared to the originally published RIs (n=6697 males/8317 females, adults from Europe). A subset of US samples was used to compare IGF-I between regions with lower (Colorado) and higher (Alabama) mean body mass index (BMI). Results: Lower limits (LLs) of RIs calculated from routine results are superimposable to LLs from the original publication for all ages and sexes, regardless whether IGF-I results were from Europe or the US. For groups with sufficient n, upper limits (ULs) of RIs calculated from European routine data were also not statistically different from the originally published central 95%. However, a striking difference exists in calculated ULs from data of European and US origin: For ages 10-18 years, calculated UL on average was 149.3 ng/mL (34.6%) higher in boys and 94.9 ng/mL (19.8%) in girls from the US. In adults (19-95 years), calculated UL on average was 45 ng/mL (20.3%) higher in males and 29.7 ng/mL (13.8%) in females from the US. Within the US, mean IGF-I was significantly higher in samples from Colorado (lower mean BMI) than in Alabama (p<0.0001) across age- and sex groups, although the difference between the two states was smaller than between each of them and Europe. Conclusion: This study provides evidence that in sufficiently large datasets, both, direct sampling (as in the original publication) and the indirect Hoffmann algorithms provide statistically comparable RI limits and may be considered as accurate representation of results distribution in the disease-free populations. More importantly, we demonstrate that even with tight cross-correlation and continuous monitoring of IGF-I assay performance RIs generated in different populations can be different. Notably, in our extremely large study, the difference between Europe and the US was clinically relevant only at the UL. Although our study cannot reveal the cause of the difference, we suggest using adapted RIs for the US.

Abstract Objectives Biotin >20.0 ng/mL (81.8 nmol/L) can reduce Elecsys® Troponin T Gen 5 (TnT Gen 5; Roche Diagnostics) assay recovery, potentially leading to false-negative results in patients with suspected acute myocardial infarction (AMI). We aimed to determine the prevalence of elevated biotin and AMI misclassification risk from biotin interference with the TnT Gen 5 assay. Methods Biotin was measured using an Elecsys assay in two cohorts: (i) 797 0-h and 646 3-h samples from 850 US emergency department patients with suspected acute coronary syndrome (ACS); (ii) 2023 random samples from a US laboratory network, in which biotin distributions were extrapolated for higher values using pharmacokinetic modeling. Biotin >20.0 ng/mL (81.8 nmol/L) prevalence and biotin 99th percentile values were calculated. AMI misclassification risk due to biotin interference with the TnT Gen 5 assay was modeled using different assay cutoffs and test timepoints. Results ACS cohort: 1/797 (0.13%) 0-h and 1/646 (0.15%) 3-h samples had biotin >20.0 ng/mL (81.8 nmol/L); 99th percentile biotin was 2.62 ng/mL (10.7 nmol/L; 0-h) and 2.38 ng/mL (9.74 nmol/L; 3-h). Using conservative assumptions, the likelihood of false-negative AMI prediction due to biotin interference was 0.026% (0-h result; 19 ng/L TnT Gen 5 assay cutoff). US laboratory cohort: 15/2023 (0.74%) samples had biotin >20.0 ng/mL (81.8 nmol/L); 99th percentile biotin was 16.6 ng/mL (68.0 nmol/L). Misclassification risk due to biotin interference (19 ng/L TnT Gen 5 assay cutoff) was 0.025% (0-h), 0.0064% (1-h), 0.00048% (3-h), and <0.00001% (6-h). Conclusions Biotin interference has minimal impact on the TnT Gen 5 assay’s clinical utility, and the likelihood of false-negative AMI prediction is extremely low.

© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Thursday 9 November 2017