False-positive Screening Tests Research Articles

Appearance of hexahydrocannabinols as recreational drugs and implications for cannabis drug testing – focus on HHC, HHC-P, HHC-O and HHC-H

This study investigated the effects of hexahydrocannabinol (HHC) and other unclassified cannabinoids, which were recently introduced to the recreational drug market, on cannabis drug testing in urine and oral fluid samples. After the appearance of HHC in Sweden in 2022, the number of posts about HHC on an online drug discussion forum increased significantly in the spring of 2023, indicating increased interest and use. In parallel, the frequency of false positive screening tests for tetrahydrocannabinol (THC) in oral fluid, and for its carboxy metabolite (THC-COOH) in urine, rose from <2% to >10%. This suggested that HHC cross-reacted with the antibodies in the immunoassay screening, which was confirmed in spiking experiments with HHC, HHC-COOH, HHC acetate (HHC-O), hexahydrocannabihexol (HHC-H), hexahydrocannabiphorol (HHC-P), and THC-P. When HHC and HHC-P were classified as narcotics in Sweden on 11 July 2023, they disappeared from the online and street shops market and were replaced by other unregulated variants (e.g. HHC-O and THC-P). In urine samples submitted for routine cannabis drug testing, HHC-COOH concentrations up to 205 (mean 60, median 27) µg/L were observed. To conclude, cannabis drug testing cannot rely on results from immunoassay screening, as it cannot distinguish between different tetra- and hexahydrocannabinols, some being classified but others unregulated. The current trend for increased use of unregulated cannabinols will likely increase the proportion of positive cannabis screening results that need to be confirmed with mass spectrometric methods. However, the observed cross-reactivity also means a way to pick up use of new cannabinoids that otherwise risk going undetected.

False-positive HIV screening test in a healthcare student.

This case report describes a 22-year-old female Ambulance Technician student who displayed human immunodeficiency virus (HIV) false positivity following a recent hepatitis B vaccination. Occupational health clinicians who work in a healthcare setting (with healthcare staff and/or students) should be aware of the possibility of false-positive HIV screening test results, and where a false positive is suspected, they should consider what the underlying cause could be and should consider whether further medical investigation is required.

Healthcare professionals' experiences of caring for women with false-positive screening test results in the National Health Service Breast Screening Programme.

Understanding healthcare professionals' (HCPs) experiences of caring for women with false-positive screening test results in the National Health Service Breast Screening Programme (NHSBSP) is important for reducing the impact of such results. Interviews were undertaken with 12 HCPs from a single NHSBSP unit, including advanced radiographer practitioners, breast radiographers, breast radiologists, clinical nurse specialists (CNSs), and a radiology healthcare assistant. Data were analysed thematically using Template Analysis. Two themes were produced: (1) Gauging and navigating women's anxiety during screening assessment was an inevitable and necessary task for all participants. CNSs were perceived as particularly adept at this, while breast radiographers reported a lack of adequate formal training. (2) Controlling the delivery of information to women (including amount, type and timing of information). HCPs reported various communication strategies to facilitate women's information processing and retention during a distressing time. Women's anxiety could be reduced through dedicated CNS support, but this should not replace support from other HCPs. Breast radiographers may benefit from more training to emotionally support recalled women. While HCPs emphasised taking a patient-centred communication approach, the use of other strategies (e.g., standardised scripts) and the constraints of the 'one-stop shop' model pose challenges to such an approach. During the study design, two Patient and Public Involvement members (women with false-positive-breast screening test results) were consulted to gain an understanding of patient perspectives and experiences of being recalled specifically in the NHSBSP. Their feedback informed the formulations of the research aim, objectives and the direction of the interview guide.

False-positive HIV screening tests during the COVID-19 pandemic, a passing trend?

False-positive fourth-generation HIV screening tests are rare and are usually associated with various infections and autoimmune diseases. SARS-CoV-2 infection and vaccination were recently linked with false-positive HIV screening test results. However, little is known about false-positives in people who performed HIV screening tests after outbreaks of different SARS-CoV-2 strains and vaccination campaigns. Here, we examined the false-positive rates in samples collected by the Israeli AIDS Task Force in 2018--2022, with respect to such factors.

The dexamethasone assay as a useful tool to identify false positive dexamethasone screening test results

The dexamethasone assay as a useful tool to identify false positive dexamethasone screening test results

The use of liquid chromatography-tandem mass spectrometry in newborn screening for congenital adrenal hyperplasia: improvements and future perspectives.

Newborn screening for congenital adrenal hyperplasia using 17-hydroxyprogesterone by immunoassay remains controversial despite screening been available for almost 40 years. Screening is confounded by poor immunoassay specificity, fetal adrenal physiology, stress, and illness which can result in a large number of false positive screening tests. Screening programmes apply higher screening thresholds based on co-variates such as birthweight or gestational age but the false positive rate using immunoassay remains high. Mass spectrometry was first applied to newborn screening for congenital adrenal hyperplasia over 15 years ago. Elevated 17-hydroxprogesterone by immunoassay can be retested with a specific liquid chromatography tandem mass spectrometry assay that may include additional steroid markers. Laboratories register with quality assurance programme providers to ensure accurate steroid measurements. This has led to improvements in screening but there are additional costs and added laboratory workload. The search for novel steroid markers may inform further improvements to screening. Studies have shown that 11-oxygenated androgens are elevated in untreated patients and that the adrenal steroidogenesis backdoor pathway is more active in babies with congenital adrenal hyperplasia. There is continual interest in 21-deoxycortisol, a specific marker of 21-hydroxylase deficiency. The measurement of androgenic steroids and their precursors by liquid chromatography tandem mass spectrometry in bloodspots may inform improvements for screening, diagnosis, and treatment monitoring. In this review, we describe how liquid chromatography tandem mass spectrometry has improved newborn screening for congenital adrenal hyperplasia and explore how future developments may inform further improvements to screening and diagnosis.

Referral rate and false-positive rates in a hearing screening program among high-risk newborns.

More studies exploring referral rates and false-positive rates are needed to make hearing screening programs in newborns better and cost-effective. Our aim was to study the referral and false-positivity rates among high-risk newborns in our hearing screening program and to analyze the factors potentially associated with false-positive hearing screening test results. A retrospective cohort study was done among the newborns hospitalized at a university hospital from January 2009 to December 2014 that underwent hearing screening with a two-staged AABR screening protocol. Referral rates and false-positivity rates were calculated and possible risk factors for false-positivity were analyzed. 4512 newborns were screened for hearing loss in the neonatology department. The referral rate for the two-staged AABR-only screening was 3.8% with false-positivity being 2.9%. Our study showed that the higher the birthweight or gestational ageof the newborn, the lower the odds of the hearingscreening resultsbeing false-positive, and the higher the chronological age of the infant at the time of screening, the higher the odds of the resultsbeing false-positive. Our study did not show a clear association between the mode of delivery or gender and false-positivity. Among high-risk infants, prematurity and low-birthweight increased the rate of false-positivity in the hearing screening, and the chronological age at the time of the test seems to be significantly associated with false-positivity.

Estimating the lifetime risk of a false positive screening test result.

False positive results in screening tests have potentially severe psychological, medical, and financial consequences for the recipient. However, there have been few efforts to quantify how the risk of a false positive accumulates over time. We seek to fill this gap by estimating the probability that an individual who adheres to the U.S. Preventive Services Task Force (USPSTF) screening guidelines will receive at least one false positive in a lifetime. To do so, we assembled a data set of 116 studies cited by the USPSTF that report the number of true positives, false negatives, true negatives, and false positives for the primary screening procedure for one of five cancers or six sexually transmitted diseases. We use these data to estimate the probability that an individual in one of 14 demographic subpopulations will receive at least one false positive for one of these eleven diseases in a lifetime. We specify a suitable statistical model to account for the hierarchical structure of the data, and we use the parametric bootstrap to quantify the uncertainty surrounding our estimates. The estimated probability of receiving at least one false positive in a lifetime is 85.5% (±0.9%) and 38.9% (±3.6%) for baseline groups of women and men, respectively. It is higher for subpopulations recommended to screen more frequently than the baseline, including more vulnerable groups such as pregnant women and men who have sex with men. Since screening technology is imperfect, false positives remain inevitable. The high lifetime risk of a false positive reveals the importance of educating patients about this phenomenon.

False-positive urine pregnancy screening tests are uncommon in the hospital setting among patients with bowel-containing urinary tract reconstruction

False-positive urine pregnancy screening tests (UPST) have been reported among patients with bowel-containing urinary reconstruction (BCUR). However, the true frequency of such inaccurate results, which have been attributed to urinary mucous or other proteins interfering with or mimicking the binding of beta-HCG in the assay, is unknown in this population. We sought to determine the incidence of false-positive pregnancy screening tests among this patient population at our institution. Using existing databases of patients with spina bifida, bladder exstrophy, and genitourinary rhabdomyosarcoma, we identified female patients with BCUR who had UPST over a 10-year period as screening prior to procedures or imaging. Patient and test result information was recorded. A total of 120 patients with a history of BCUR were identified: 33 with spina bifida, 73 within the exstrophy-epispadias complex (EEC), and 14 with genitourinary rhabdomyosarcoma. Of this group, 46 patients (38%) had at least one UPST during the study period; 15 had 1 UPST, 6 had 2 UPSTs, 4 had 3 UPSTs, and 21 had greater than 3 UPSTs, for a total of 244 UPST in this cohort. UPSTs used at our institution included Sure-Vue brand and Alere brand (HCG sensitivity 20mIU/ml). Types of BCUR included ileal enterocystoplasty in 25 patients, colon enterocystoplasty in 6, stomach enterocystoplasty in 5, composite enterocystoplasty in 7, and continent catheterizable channel alone (e.g. Yang-Monti, appendicovesicostomy) in 3 patients. Of the 244 UPSTs in patients with BCUR, zero (0%) were positive. Despite reports in the literature that false-positive UPST are common among patients with bowel-containing urinary diversions, we found no positive UPST among patients with BCUR in the healthcare setting. False-positive UPST in the home setting may be due to variability in sensitivity thresholds, binding agents, technical errors in test technique, kit quality control, or other factors.

Comparing the Characteristics of Neonates with FalsePositive Congenital Hypothyroidism Screening Results with Affected Neonates

Background: Congenital hypothyroidism is one of the most common preventable causes of mental retardation. The present study aimed to compare the characteristics of neonates with false-positive congenital hypothyroidism screening test results with affected neonates in Kerman. Methods: This cross-sectional study was conducted on neonates called to confirm congenital hypothyroidism from 2016 to 2017. The neonate characteristics (year and season of birth, sex, umbilical hernia, fontanelle conditions, constipation, jaundice, abnormalities, head circumference, height and weight at birth, gestational age, type of delivery, parental consanguinity, history of thyroid disease in the family, childbirth location, history of hospitalization, and place of residence) and maternal characteristics (age, number of deliveries, history of stillbirth, history of illness, and drug use during pregnancy) were extracted from their medical records. The collected data were analyzed with SPSS software (version 20) using the chi-square and independent samples t test. Results: From a total of 985 neonates who had a positive screening test, congenital hypothyroidism was confirmed in only 58 neonates(5.9%), and the other 927 neonates(94.1%) only had a positive screening test. The neonates’ and mothers’ characteristics were not significantly different in the two groups, except for constipation, which had a higher frequency in the neonates with a positive congenital hypothyroidism screening results than in the affected neonates (P=0.004). Conclusion: In this study, the characteristics of neonates who only had a positive hypothyroidism screening test result were not significantly different from those of the affected neonates. It is recommended that further studies be conducted over a longer period.

Relationship between False Positive Screening Results of Down Syndrome and Adverse Pregnancy Outcomes.

Maternal serum sample screening in the first and second trimesters has been commonly used to identify women who are at risk of fetal trisomy 21. In addition, these serum markers are associated with adverse perinatal outcomes. Hence, the present study was conducted to determine the relationship between false positive screening results of Down syndrome and adverse pregnancy outcomes. This prospective, two-group, cohort study was conducted on 608 pregnant women who had undergone fetal contingent screening. They were selected through convenience sampling in the twentieth week of pregnancy and were followed up until delivery. The raw Odd Ratios (OR), Relative Risk (RR), and adjusted OR of adverse pregnancy outcomes were calculated in the false positive and true negative groups. The adjusted OR of developing preeclampsia was 1.98 (95%CI: 1.14-3.42), and its RR was 2.13 (95%CI: 1.34-3.38) times higher in the false positive group. Moreover, the adjusted OR of Small for Gestational Age (SGA) was 2.80 (95%CI: 1.76-4.47), and its RR was 2.28 (95%CI: 1.54-3.36) times higher in the false positive group. The adjusted OR of Low Birth Weight (LBW) was 3.34 (95%CI: 1.97-5.64), and its RR was 2.65 (95%CI: 1.72-4.11) times higher in the false positive group. In addition, no significant difference was observed between false positive and true negative groups in terms of preterm birth. Women with a false positive fetal screening test result are more likely to suffer from preeclampsia, SGA, and LBW and require planned prenatal care.

Screening for prostate cancer: protocol for updating multiple systematic reviews to inform a Canadian Task Force on Preventive Health Care guideline update

PurposeTo inform updated recommendations by the Canadian Task Force on Preventive Health Care on screening for prostate cancer in adults aged 18 years and older in primary care. This protocol outlines the planned scope and methods for a series of systematic reviews.MethodsUpdates of two systematic reviews and a de novo review will be conducted to synthesize the evidence on the benefits and harms of screening for prostate cancer with a prostate-specific antigen (PSA) and/or digital rectal examination (DRE) (with or without additional information) and patient values and preferences. Outcomes for the benefits of screening include reduced prostate cancer mortality, all-cause mortality, and incidence of metastatic prostate cancer. Outcomes for the harms of screening include false-positive screening tests, overdiagnosis, complications due to biopsy, and complications of treatment including incontinence (urinary or bowel), and erectile dysfunction. The quality of life or functioning (overall and disease-specific) and psychological effects outcomes are considered as a possible benefit or harm. Outcomes for the values and preferences review include quantitative or qualitative information regarding the choice to screen or intention to undergo screening. For the reviews on benefits or harms, we will search for randomized controlled trials, quasi-randomized, and controlled studies in MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. For the review on values and preferences, we will search for experimental or observational studies in MEDLINE, Embase, and PsycInfo. For all reviews, we will also search websites of relevant organizations, gray literature, and reference lists of included studies. Title and abstract screening, full-text review, data extraction, and risk of bias assessments will be completed independently by pairs of reviewers with any disagreements resolved by consensus or by consulting with a third reviewer. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach will be used to assess the certainty of the evidence for each outcome.DiscussionThe series of systematic reviews will be used by the Canadian Task Force on Preventive Health Care to update their 2014 guideline on screening for prostate cancer in adults aged 18 years and older.Systematic review registrationThis review has been registered with PROSPERO (CRD42022314407) and is available on the Open Science Framework (osf.io/dm32k).

Analysis of the characteristics of patients with false-positive HIV screening assay results

ObjectiveTo investigate the clinical characteristics of patients with false-positive human immunodeficiency virus (HIV) screening test results and provide a theoretical basis to interpret the results of HIV screening tests. MethodsThis retrospective study evaluated the incidence of false-positive results for HIV screening tests and characterized false-positive reactions during HIV screening in a large-scale study at Zhongshan Hospital, Xiamen University. ResultsFalse-positive HIV test results occurred for 264 of 275,263 (0.10%) serum samples. Although the incidence of a false-positive HIV screening result did not differ between male and female patients (screening χ2 = 1.194; P = 0.275), it increased with age (χ2 = 25.759; P < 0.01). False-positive reactions were associated with 16 disease categories, including 101 diseases, some of which have never been reported previously to be associated with false-positive HIV screening results. ConclusionsThe occurrence of false-positive HIV screening test results may indicate underlying serious disorders. Characterization of patients with false-positive HIV screening test results can help identify potential diseases unrelated to HIV.

Mexiletine and False Positive Urine Drug Screen for Amphetamine: A Case Review

Advanced heart failure patients commonly suffer from ventricular arrhythmias which can be managed by antiarrhythmic drugs like mexiletine. These ventricular arrhythmias can be complicated by illicit drug use which alter outcomes and can potentially impact the patient-physician relationship through countertransference. However, mexiletine can lead to false positive urine drug screen testing for amphetamine, and these false-positive urine drug screen test results can affect the decision-making process. Health care providers should be aware of this fact and should either use confirmatory testing or look for confounding compounds in patients who deny using illicit substances and have a positive urine drug screen. Our patient is 64 years old who arrived at the emergency department after experiencing a shock by his intracardiac defibrillator. The patient tested positive for amphetamine on his urine drug screen and was later ruled out by confirmatory quantitative testing.

Elevated newborn serum immunoreactive trypsinogen associated with a congenital pancreatic cyst

Congenital abdominal cysts have a broad differential diagnosis. Pancreatic cysts are rare lesions that offer a diagnostic and surgical challenge to surgeons. We report on a case of a large left upper quadrant cyst detected in utero , which remained of unclear etiology despite cross-sectional imaging at birth. Intraoperative findings confirmed its pancreatic origin. In hindsight, a pre-operative elevated immunoreactive trypsinogen, performed as part of universal cystic fibrosis (CF) newborn screening, may have suggested the diagnosis. False-positive CF screening tests may be unnoticed by a surgical team assessing infants with an abdominal mass. As universal testing for cystic fibrosis increases in Canada and worldwide, physicians should review a patient's CF screening history. Elevated immunoreactive trypsinogen levels with normal sweat chloride and cystic fibrosis transmembrane conductance regulator (CFTR) detection tests may orient towards a pancreatic etiology when assessing a patient with a congenital abdominal cyst of unclear etiology. • Investigate false-positive cystic fibrosis screening tests when assessing patients with a congenital abdominal cyst. • High immunoreactive trypsinogen levels on cystic fibrosis screening tests may be a marker of congenital pancreatic cysts. • Negative sweat chloride test and genetic testing were not enough to rule out a pancreatic etiology in our case.

Association between low first trimester maternal serum PAPP-A levels and presence of unilateral or bilateral uterine artery diastolic notches

Objective Uterine artery impedance is known to have an effect on first trimester aneuploidy screening biomarkers. In this study we aim to compare first trimester screening parameters in women with and without uterine artery diastolic notches. Methods This retrospective case control study was conducted in a single tertiary center by obtaining medical records of women that admitted for first trimester pregnancy follow-up. Singleton pregnancies without structural anomalies, chromosomal anomalies and obstetric complications were included in the study. 268 women with first trimester unilateral uterine artery diastolic notches are constituted study group 1, 149 women with bilateral uterine artery diastolic notches constituted study group 2. 200 women were randomly selected as control group. Results Significantly decreased PAPP-A levels were found in both study groups. PAPP-A levels were even lower in women with bilateral notches in comparison to unilateral notches. Fetal birth weights and gestational ages at birth were also found significantly lower in study groups. Beta human chorionic gonadotropin levels and nuchal translucency measurements were found similar. Prevalence of false positive first trimester aneuploidy screening test results were significantly higher in women with bilateral uterine artery diastolic notches. Conclusion Presence of first trimester uterine artery diastolic notches, particularly the presence of bilateral diastolic notches, is related with decreased PAPP-A levels in first trimester aneuploidy screening and lead to higher false positive rates in first trimester aneuploidy screening and consequently more unnecessary invasive procedures.

False-positive HIV screening test in a patient with pulmonary embolism because of severe acute respiratory syndrome coronavirus 2 infection.

False-positive HIV screening test in a patient with pulmonary embolism because of severe acute respiratory syndrome coronavirus 2 infection.

Nonhomogeneous Markov chain for estimating the cumulative risk of multiple false positive screening tests.

Screening tests are widely recommended for the early detection of disease among asymptomatic individuals. While detecting disease at an earlier stage has the potential to improve outcomes, screening also has negative consequences, including false positive results which may lead to anxiety, unnecessary diagnostic procedures, and increased healthcare costs. In addition, multiple false positive results could discourage participating in subsequent screening rounds. Screening guidelines typically recommend repeated screening over a period of many years, but little prior research has investigated how often individuals receive multiple false positive test results. Estimating the cumulative risk of multiple false positive results over the course of multiple rounds of screening is challenging due to the presence of censoring and competing risks, which may depend on the false positive risk, screening round, and number of prior false positive results. To address the general challenge of estimating the cumulative risk of multiple false positive test results, we propose a nonhomogeneous multistate model to describe the screening process including competing events. We developed alternative approaches for estimating the cumulative risk of multiple false positive results using this multistate model based on existing estimators for the cumulative risk of a single false positive. We compared the performance of the newly proposed models through simulation studies and illustrate model performance using data on screening mammography from the Breast Cancer Surveillance Consortium. Across most simulation scenarios, the multistate extension of a censoring bias model demonstrated lower bias compared to other approaches. In the context of screening mammography, we found that the cumulative risk of multiple false positive results is high. For instance, based on the censoring bias model, for a high-risk individual, the cumulative probability of at least two false positive mammography results after 10 rounds of annual screening is 40.4.

1061. False Positive Human Immunodeficiency Virus Testing Due to Acute Hepatitis A Infection: A Case Series

BackgroundIn our urban, underserved patient population, Human Immunodeficiency Virus (HIV) is hyper-endemic, and HIV screening is frequently performed. Although HIV screening tests have high specificity, false positives can occur. Numerous reasons for false positive testing have been cited, including vaccinations, autoimmune diseases, and viral infections. In 2019, Philadelphia experienced a large Hepatitis A outbreak, during which time false positive HIV screening tests were discovered. Our aim was to further describe these patients who had been diagnosed with acute Hepatitis A infection and in whom false positive HIV testing had occurred.MethodsWe conducted a retrospective chart review of adult patients admitted to our hospital between January 2017 and December 2019 who had a positive Hepatitis A Virus (HAV) IgM. Demographics, HIV tests, viral hepatitis tests, and liver tests were recorded. False positive HIV was defined as a positive HIV screen (p24 antigen and HIV-1 and 2 antibody combo), followed by a negative differentiation assay for HIV-1 and 2 antibodies, combined with a negative HIV PCR.ResultsA total of 156 unique patients were found to have acute HAV, with 138 cases identified in 2019. Of these, 3 patients had confirmed false positive HIV testing, and 1 patient had suspected false positive HIV testing (HIV-2 differentiation assay indeterminate, with very low local prevalence of HIV-2), for a false positive test rate of 2.6% (4/156). Ages ranged from 36-47 years, 3 were male, and 2 were persons who injected drugs (PWID). Three patients had prior negative HIV testing. Two patients had fevers during admission, but none of the four were febrile at the time of HIV test collection. Three patients had elevated transaminases, and two had abnormal coagulation testing. Coinfection with Hepatitis C was found in three patients. One patient had follow-up HIV testing performed, which was negative.ConclusionTo our knowledge, this is the first report of false positive HIV testing related to acute HAV. Prevalence of false positives was low, but awareness can facilitate patient counseling. With low sample size, conclusions cannot be drawn about risk factors related to false positive testing.Disclosures All Authors: No reported disclosures

773. Screening for Chagas disease in East Boston, Massachusetts from 2017 – 2020 reveals 0.9% prevalence

BackgroundThis study reports on the results of a screening program for Chagas disease in East Boston.MethodsBased at the East Boston Neighborhood Health Center, the Strong Hearts Program offers continuing medical education sessions on Chagas disease to providers in Adult Medicine, Pediatrics, Family Medicine and Obstetrics. Providers are encouraged to offer one-time screening for Chagas disease for all patients who lived in Mexico, South or Central America for ≥6 months, at their discretion. A commercial lab performs the initial screening test using the Hemagen ELISA while confirmatory testing is performed at the US CDC. For each patient, completion of screening requires a multi-step process consisting of splitting the serum sample to save a frozen aliquot for send out to CDC if the ELISA is positive/indeterminate, monitoring screening results to send the saved aliquot to the CDC if indicated, filling out the CDC requisition, shipping the serum aliquot, and monitoring the result returning from the CDC. Patients diagnosed with confirmed Chagas disease are referred to Boston Medical Center for further evaluation and treatment if indicated.ResultsFrom 3/21/2017 – 5/18/2020, 8,142 patients were screened. 423 (5.2%) patients had an initial positive test, 7,669 (94.2%) initially tested negative and 50 were indeterminate (0.6%). Among those with a positive screening result, 76 were confirmed to have T. cruzi infection for an overall prevalence of 0.93% in this population. 293 (69.3%) patients with positive screening tests had a negative (discordant) confirmatory test, 18 (4.3%) had an indeterminate test, and 36 (8.5%) had results that were unavailable or pending as of this analysis. None of the indeterminate screening tests were positive upon confirmation.ConclusionPrevalence of infection with T. cruzi was nearly 1% among patients in East Boston who had lived in Latin America. Diagnosis of Chagas was challenging due to a large number of false positive screening tests. The resource burden imposed by current screening options is itself a barrier to addressing Chagas disease. Given the significant prevalence of Chagas disease in the US, increased access to tests (i.e., two-step screening conducted through commercial laboratories) and screening assays with improved specificity are needed.Disclosures All Authors: No reported disclosures