Point-of-care Testing Strategies Research Articles

Rapid and supersensitive allele detection of Plasmodium falciparum chloroquine resistance via a Pyrococcus furiosus argonaute-triggered dual-signal biosensing platform

BackgroundMalaria remains a serious public health problem worldwide, particularly in Africa. Resistance to antimalarial drugs is an essential issue for malaria control and elimination. Currently, polymerase chain reaction (PCR) combined with Sanger sequencing is regarded as the gold standard for mutation detection. However, this method fails to meet the requirements of point-of-care testing (POCT) because of its time-consuming, expensive instruments and professional dependence. To support this strategy, we developed a novel diagnostic platform that combines recombinase polymerase amplification (RPA) with the Pyrococcus furiosus argonaute (PfAgo) protein and was designed to detect gene mutations related to antimalarial drug resistance. The Pfcrt haplotypes CVMNK and CVIET of chloroquine resistance (CQR) were used as examples and were assessed in this study.MethodsBy meticulously designing strategies, RPA primers, guide DNAs, and probes were screened, the reaction was optimized, and the resulting parameters were employed to ascertain the genotype of Pfcrt. The recombinant plasmids pUC57/Pfcrt-CVIET and pUC57/Pfcrt-CVMNK were constructed and diluted for sensitivity detection. The pUC57/Pfcrt-CVIET plasmid mixture was added to the pUC57/Pfcrt-CVMNK plasmid mixture in different additions to configure several specific proportions of mixed plasmid mixtures. The RPA-PfAgo platform was used, and the mixed plasmid was detected simultaneously via nest-PCR (nPCR) and Sanger sequencing. The platform was then evaluated on 85 clinical samples and compared with Sanger sequencing.ResultsThe entire process achieves the key mutation Pfcrt-CVMNK/CVIET genotype identification of CQR within 90 min. The platform achieved 1.8 × 104 copies/μL sensitivity and could detect as little as 3% CVIET in mixed plasmids, which is a higher sensitivity than that of Sanger sequencing (5%). Notably, the platform shows 100% concordance with the gold standard method when 85 clinical samples are tested. The sensitivity and specificity were 100% for the 85 clinical samples.ConclusionsThis study established an RPA-PfAgo platform for genotyping the key mutation Pfcrt-CVMNK/CVIET of CQR. This method can rapidly produce reliable results and avoid the disadvantages of nPCR with sequencing. This approach has the characteristics of a short operation time, low device dependence, and a good match to the POCT strategy, suggesting that the platform can be easily applied locally or on site.Graphical abstract

Bisphenol a monitoring by commercial pregnancy test strips transformed by DNA walking machine

Frequently occurred food contamination issues bring about a tremendous global demand for point-of-care testing (POCT) devices. Pregnancy test strip (PTS) retains the highest POCT market share and a low cost of $0.10 per test, but challenged by limited analytical sensitivity and non-autonomous signal transduction for drink contaminant monitoring. Herein, we developed a DNA walking machine-assisted commercial PTS method for on-site bisphenol A (BPA) analysis. DNAzyme was operated as the efficient autonomous catalytic walker chain to drive the DNA machine for the amplified signal output of BPA in drink samples. A detection limit of 16.8 pg/mL was obtained. The POCT strategy constructed in this work has the characteristics of low cost, convenient operation and high analytical sensitivity, represents an attractive option for biosensing and on-site drink safety monitoring.

Sputum and tongue swab molecular testing for the in-home diagnosis of tuberculosis in unselected household contacts: a cost and cost-effectiveness analysis.

Delayed and missed diagnosis are a persistent barrier to tuberculosis control, partly driven by limitations associated with sputum collection and an unmet need for decentralized testing. Household contact investigation with point-of-care testing of non-invasive specimens like tongue swabs are hitherto undescribed and may be a cost-effective solution to enable community-based active case finding. In-home, molecular point-of-care testing was conducted using sputum and tongue specimens collected from all household contacts of confirmed tuberculosis cases. A health economic assessment was executed to estimate and compare the cost and cost-effectiveness of different in-home, point-of-care testing strategies. Incremental cost effectiveness ratios of strategies utilizing different combination testing algorithms using sputum and/or tongue swab specimens were compared. The total implementation cost of delivering the standard of care for a 2-year period was $84 962. Strategies integrating in-home point-of-care testing ranged between $87 844 - $93 969. The cost-per-test for in-home, POC testing of sputum was the highest at $20·08 per test. Two strategies, Point-of-Care Sputum Testing and Point-of-Care Combined Sputum and Individual Tongue Swab Testing were the most cost-effective with ICERs of $543·74 and $547·29 respectively, both below a $2,760 willingness-to-pay threshold. An in-home, point-of-care molecular testing strategy utilizing combination testing of tongue swabs and sputum specimens would incur an additional 10.6% program cost, compared to SOC, over a 2-year period. The increased sample yield from tongue swabs combined with immediate result notification following, in-home POC testing would increase the number of new TB cases detected and linked to care by more than 800%.

A SERS-based point-of-care testing approach for efficient determination of diquat and paraquat residues using a flexible silver flower-coated melamine sponge

Diquat (DQ) and paraquat (PQ) residues in food are potential hazards to consumers' health. Point-of-care testing (POCT) of them remains challenging. Based on surface-enhanced Raman spectroscopy (SERS) technology, we developed a POCT strategy for DQ and PQ on apple surface and in apple juice. A point-of-use composite was fabricated using a piece of porous melamine sponge (MS) modified with silver nanoflowers (AgNFs), combining the specificity of the SERS fingerprint and the excellent adsorption capacity of MS. Using this dual-functional AgNFs@MS, the on-site determination of the DQ and PQ residues was completed within 3 min without pretreatment. Clear trends were observed between SERS intensity and logarithmic concentrations, with r values from 0.962 to 0.984. The limit of detection of DQ and PQ were 0.14–0.70 ppb in apple juice and on apple surface. This study provides a new point-of-use alternative for rapidly detecting DQ and PQ residues in nonlaboratory settings.

A survey of community pharmacists’ and healthcare advisors’ views and experiences on the provision of a Test and Treat Service for uncomplicated lower urinary tract infection in a retail pharmacy chain in Ireland

Abstract Introduction The use of Point of Care Testing (POCT) as an aid to guide antibiotic prescribing has been highlighted in Ireland’s second One Health National Action Plan on Antimicrobial Resistance 2021-2025 (iNAP2).[1] The role of community pharmacy is expanding with the introduction of antimicrobial stewardship (AMS) POCT strategies. Uncomplicated urinary tract infections (UTIs) are frequent and burdensome in the community. With antibiotic resistance on the rise amongst uropathogens, AMS efforts to reduce inappropriate antibiotic prescribing for urinary symptoms are paramount. Aim To evaluate community pharmacy staff views and experiences on the provision of a Cystitis Test-and-Treat Service for uncomplicated UTIs, while identifying opportunities for service improvement and expansion. Methods An electronic survey on Microsoft® Forms was distributed within a large retail pharmacy chain in Ireland during November 2021, with two reminders issued. Pharmacists and Healthcare advisors over the age of 18, working in 88 pharmacies that provided the Velieve Cystitis Test-and-Treat Service were eligible to participate. The survey was subdivided into participant demographics, local UTI information, views and experiences of participants on the Cystitis Test-and-Treat Service, the patient information leaflet and the training completed by pharmacy staff providing the service and included open-ended and closed-ended or Likert-scale questions. The survey was developed based on the literature and was revised following the contributions of pharmacy chain pharmacists and its Research Governance Committee who have a working knowledge of Service. Data were analysed using Microsoft® Excel and IBM® SPSS® statistics version 28.0. Qualitative data from the open-ended survey questions were analysed using thematic analysis. Results A total of 43 pharmacy staff (18 pharmacists and 25 healthcare advisors) participated in the study (overall participation rate of 10.2%). The majority of participants were female (83.7%) and most pharmacies were located in a town/suburb area (55.8%). The majority of participants (76.7%) estimated that service users with symptoms suggestive of UTI present to the pharmacy first, before visiting their GP. Participants believed that the Cystitis Test-and-Treat Service improved service user satisfaction in symptom management, reduced antimicrobial prescribing, alongside reduced general practitioner workload. High acceptability was attributed to the speed and convenience of the service, while time cost and time required explaining the service were identified as barriers. The associated smartphone application was identified as a service weakness. Participants recommended extended training on service user eligibility with perhaps training videos to improve overall confidence. While the low response rate and small sample size is a limitation of this study, the inclusion of participants from two differing pharmacy roles strengths the findings. Conclusion This study highlights that POCT are feasible AMS initiatives that enhance management of uncomplicated UTI and could be incorporated into community pharmacy practice. The perceived ‘poor public awareness of the service’ reported by the participants, suggests the need for increased promotion and advertising.

Research progress of visual detection in rapid on-site detection of pathogen nucleic acid.

Nucleic acid detection is widely used in pathogen screening and detection due to its high sensitivity and specificity. With the increase of detection requirements and the development of amplification technology, nucleic acid detection methods are gradually developing towards simple, fast and low-cost. Quantitative polymerase chain reaction (qPCR), as the "gold standard" for nucleic acid detection, relies on expensive equipment and professional operators, which is not suitable for rapid on-site detection of pathogens. The visual detection method without relying on excitation light source or complex equipment can present the detection results in a more intuitive and portable way after combining with rapid and efficient amplification technology, which has the potential of point-of-care testing (POCT). This paper focuses on the reported application of amplification technology and CRISPR/Cas technology in visual detection and compares their advantages and disadvantages, so as to provide reference for POCT strategy based on pathogen nucleic acid.

Two birds with one stone: A multifunctional nanoplatform for photothermal sensitive detection and real-time inactivation of Staphylococcus aureus with NIR responsive Cu2−XSe@Van NPs

Susceptibility point-of-care testing (POCT) and bacterial inactivation are crucial for food safety and clinical diagnosis since bacteria pose a severe hazard to public health and healthcare. To enable photothermal determination and hyperthermal inactivation of bacteria, vancomycin-modified near-infrared (NIR)-responsive copper selenide nanoparticles (Cu2−XSe@Van NPs) with excellent photothermal conversion are synthesized here. Cu2−XSe@Van NPs can be trapped on the surface of Gram-positive bacteria such as Staphylococcus aureus (S. aureus), forming a Cu2−XSe@Van NPs/S. aureus complex. Suspension (Cu2−XSe@Van NPs) and sediment (Cu2−XSe@Van NPs/S. aureus) can convert the NIR laser energy into a thermal signal that can be detected by the thermal camera at concentrations as low as 6.0 CUF mL−1. Meanwhile, S. aureus can be effectively inactivated by localized temperature rises during temperature-based signal detection. The antibacterial efficiency can reach as high as 99.53%. The proposed strategy not only provides a sensitive POCT strategy for bacterial determination but also implements efficient inactivation of bacteria simultaneously.

Recent advances in point-of-care testing of COVID-19.

Advances in microfluidic device miniaturization and system integration contribute to the development of portable, handheld, and smartphone-compatible devices. These advancements in diagnostics have the potential to revolutionize the approach to detect and respond to future pandemics. Accordingly, herein, recent advances in point-of-care testing (POCT) of coronavirus disease 2019 (COVID-19) using various microdevices, including lateral flow assay strips, vertical flow assay strips, microfluidic channels, and paper-based microfluidic devices, are reviewed. However, visual determination of the diagnostic results using only microdevices leads to many false-negative results due to the limited detection sensitivities of these devices. Several POCT systems comprising microdevices integrated with portable optical readers have been developed to address this issue. Since the outbreak of COVID-19, effective POCT strategies for COVID-19 based on optical detection methods have been established. They can be categorized into fluorescence, surface-enhanced Raman scattering, surface plasmon resonance spectroscopy, and wearable sensing. We introduced next-generation pandemic sensing methods incorporating artificial intelligence that can be used to meet global health needs in the future. Additionally, we have discussed appropriate responses of various testing devices to emerging infectious diseases and prospective preventive measures for the post-pandemic era. We believe that this review will be helpful for preparing for future infectious disease outbreaks.

GNP/CNT nanocomposite coated screen-printed electrode for point-of-care testing of dopamine in human serum

It is very important to develop point-of-care (POC) testing method of dopamine (DA) in human tissue to help the diagnosis and treatment of the diseases such as Parkinson and Depression. Fortunately, carbon nanotechnology offers an opportunity to solve this problem. In this paper, graphene nanoplate/carbon nanotubes (GNP/CNT) nanocomposite screen-printed electrodes (SPE) has been developed with a unique waterborne carbon nanocoating technology. The resulting GNP/CNT SPE has a linear DA detection range from 0.4 μM to 40 μM with differential pulse voltammetry (DPV) method, with an excellent anti-interference to the ascorbic acid (AA) and urea (UA). As a result, DA in human serum can be measured with POC testing strategy. The excellent sensing mechanism are proved to be the high electrical conductivity and the large specific surface area of carbon space network structure of CNT connected GNP; high diffusion rate of DA driven by electrostatic attraction and the oxidative catalytic activity based on the pi-pi interfacial interaction between GNP/CNT electrode and DA.

Effectiveness and use of reverse transcriptase polymerase chain reaction point of care testing in a large-scale COVID-19 surveillance system.

BackgroundRapid COVID‐19 testing platforms can identify infected individuals at the point of care (POC), allowing immediate isolation of infected individuals and reducing the risk of transmission. While lab‐based nucleic acid amplification testing (NAAT) is often considered the gold standard to detect SARS‐CoV‐2 in the community, results typically take 2–7 days to return, rendering POC testing a critical diagnostic tool for infection control. The National Football League (NFL) and NFL Players Association deployed a new POC testing strategy using a newly available reverse transcriptase polymerase chain reaction (RT‐PCR) rapid test during the 2020 season, and evaluated diagnostic effectiveness compared to other available devices using real‐world population surveillance data.MethodsRT‐PCR POC test results were compared to NAAT results from same‐day samples by calculation of positive and negative concordance. Sensitivity analyses were performed for three subgroups: (1) individuals symptomatic at time of positive test; (2) individuals tested during the pilot phase of rollout; and (3) individuals tested daily.ResultsAmong 4989 same‐day POC/NAAT pairs, 4957 (99.4%) were concordant, with 93.1% positive concordance and 99.6% negative concordance. Based on adjudicated case status, the false negative rate was 0.2% and false positive rate was 2.9%. In 43 instances, the immediate turnaround of results by POC allowed isolation of infected individuals 1 day sooner than lab‐based testing. Positive/negative concordance in sensitivity analyses were relatively stable.ConclusionRT‐PCR POC testing provided timely results that were highly concordant with lab‐based NAAT in population surveillance. Expanded use of effective RT‐PCR POC can enable rapid isolation of infected individuals and reduce COVID‐19 infection in the community.

An Aptasensing Strategy Using the Phosphatase‐mimic Nanozyme and pH Meter as Signal Readout

AbstractThe demand for point‐of‐care testing (POCT) is growing dramatically, especially for district where health facilities are poorly staffed, poorly skilled and ill‐equipped. As a commercialized portable device, pH meters can be used for detection of various targets, relying on bioactive enzymes. The nanozymes, as the alternative of the natural enzymes, have rarely been used for pH‐metric POCT strategies. Herein, we developed an ultrasensitive pH‐metric sandwich‐type aptasensor based on the CeO2 nanorods (CeO2 NRs) as phosphatase‐mimic and sodium monofluorophosphate (MFP) as catalytic substrate. Under optimal conditions, such strategy yields a detection limit of 1.17 nM with eligible selectivity for detecting thrombin.

An Update on Molecular Diagnostics for COVID-19.

A novel strain of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) disease (COVID-19) has been recently identified as an infectious disease affecting the respiratory system of humans. This disease is caused by SARS-CoV-2 that was identified in Chinese patients having severe pneumonia and flu-like symptoms. COVID-19 is a contagious disease that spreads rapidly via droplet particles arising through sneezing and coughing action of an infected person. The reports of asymptomatic carriers changed the scenario of symptom based-diagnosis in COVID-19 and intensified the need for proper diagnosis of the majority of the population to combat the rapid transmission of virus. The diagnosis of positive cases is necessary to ensure prompt care to affected people and also to curb further spread of infection in the population. Collecting samples at the right time and from the exact anatomical site is crucial for proper molecular diagnosis. After the complete genome sequence was available, China formulated RT-PCR as a primary diagnostic procedure for detecting SARS-CoV-2. Many in-house and commercial diagnostic kits have been developed or are under development that have a potential to lower the burden of diagnosis on the primary diagnostic techniques like RT-PCR. Serological based diagnosis is another broad category of testing that can detect different serum antibodies like IgG, IgM, and IgA in an infected patient. PCR-based diagnostic procedures that are commonly used for pathogen detection need sophisticated machines and assistance of a technical expert. Despite their reliable accuracy, they are not cost-effective tests, which a common man can afford, so it becomes imperative to look for other diagnostic approaches, which could be cost effective, rapid, and sensitive with consistent accuracy. To make such diagnostics available to the common man, many techniques can be exploited among, which are Point of Care (POC), also known as bed side testing, which is developing as a portable and promising tool in pathogen diagnosis. Other lateral flow assay (LFA)-based techniques like SHERLOCK, CRISPR-Cas12a (AIOD-CRISPR), and FNCAS9 editor-limited uniform detection assay (FELUDA), etc. have shown promising results in rapid detection of pathogens. Diagnosis holds a critical importance in the pandemic situation when there is no potential drug for the pathogen available in the market. This review sums up the different diagnostic approaches designed or proposed to combat the crisis of widespread diagnosis due to the sudden outbreak of a novel pathogen, SARS-CoV-2 in 2019.

Point-of-care testing of MicroRNA based on personal glucose meter and dual signal amplification to evaluate drug-induced kidney injury

The upregulation or downregulation of microRNA-21 (miRNA-21) is closely related with drug-induced kidney injury (DIKI). As a potential and significant biomarker, the point-of-care testing (POCT) of miRNA-21 is worthy of attention and can provide essential information for clinical diagnosis. Hence, we design a portable and sensitive POCT assay for miRNA-21 using personal glucose meters (PGM). The whole operational system is constructed on streptavidin-coated magnetic beads (MBs) modified with substrate strands linked invertase and DNAzyme molecules each silenced by a locking strand. In the presence of miRNA-21, the locking strand can hybridize to miRNA-21, which originates the activation of the DNAzyme. The DNAzyme cleaves the substrate strands and induces the release of invertase from the surface of MBs. The separated invertase hydrolyzes sucrose to glucose which can be measured by PGM. The dual enzyme mediated catalyzation by DNAzyme and invertase therefore triggers the signal amplification. We establish a linear relationship between PGM and different concentration of miRNA-21 in the range of 100 fM to 1 pM. The limit of detection is 68.08 fM, which is comparable with some of the previous reports. The biosensor also exhibits excellent sequence selectivity, well-presented reproducibility and stability. Notably, by detecting miRNA-21 in urine, this method has been successfully used to predict DIKI and evaluate the protection effect of drugs on DIKI. Therefore, a dependable and low-cost POCT strategy for the detection of miRNA-21 is established, which is promising to supply valuable information for drug screening and evaluation of DIKI.

Clinical effect and cost-effectiveness of incorporation of point-of-care assays into early infant HIV diagnosis programmes in Zimbabwe: a modelling study

New point-of-care (POC) assays for early infant HIV diagnosis are costlier than conventional total nucleic acid assays, but could increase access to testing, shorten time to results, and expedite initiation of antiretroviral therapy. We aimed to assess the clinical benefits and cost-effectiveness of incorporating these POC assays into early infant diagnosis programmes in Zimbabwe. We used the Cost Effectiveness of Preventing AIDS Complications (CEPAC)-Pediatric model to examine the clinical benefits, costs, and cost-effectiveness of replacing conventional assays for early infant HIV diagnosis with POC assays at age 6 weeks in Zimbabwe. We simulated two strategies for early infant HIV diagnosis: conventional and POC. Modelled assays differed in sensitivity; specificity; time to, and probability of, return of results; and cost. Model outcomes included survival, life expectancy, and mean lifetime per-person treatment cost, which were reported separately for all HIV-exposed infants and all infants with HIV. We calculated incremental cost-effectiveness ratios with discounted (3% per year) costs and life expectancy from a health-care system perspective for all HIV-exposed infants. We judged incremental cost-effectiveness ratios of $1010 (Zimbabwe's annual gross domestic product per person) or less per year of life saved to be cost-effective. When conventional assays were used for early infant diagnosis, projected undiscounted life expectancy was 22·7 years for infants with HIV and 62·5 years for all HIV-exposed infants, at a cost of $610 per HIV-exposed infant. Use of POC assays for early infant HIV diagnosis improved projected undiscounted life expectancy to 25·5 years among infants with HIV and 62·6 years among HIV-exposed infants at a cost of $690 per HIV-exposed infant. At age 12 weeks, survival among all infants with HIV was 76·1% with the conventional testing strategy and 83·5% with the POC testing strategy. The incremental cost-effectiveness ratio of POC assays versus conventional assays for early infant diagnosis was $680 per year of life saved. When conventional assay characteristics remained constant, this ratio remained under the cost-effectiveness threshold as long as the specificity and sensitivity of the POC assay were greater than 92% and 65%, respectively. Our results were robust to plausible variations in POC assay cost, the probability of ART initiation, and probability of return of the results of POC testing. Compared with conventional assays, POC assays for early infant HIV diagnosis in Zimbabwe will improve survival, extend life expectancy, and be cost-effective for HIV-exposed infants. Elizabeth Glaser Pediatric AIDS Foundation, US National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and Unitaid.

Rapid diagnostic tests relying on antigen detection from stool as an efficient point of care testing strategy for giardiasis and cryptosporidiosis? Evaluation of a new immunochromatographic duplex assay

Microscopy is the gold standard for the diagnosis of gastrointestinal parasites but is time-consuming and dependent on operator skills. Rapid diagnostic tests represent alternative methods but most evaluations have been conducted on a limited number of samples preventing their implementation in the clinical setting. We evaluated a new CE-IVD marked immunochromatographic assay (Crypto/Giardia K-SeT®, Coris Bioconcept) for the detection of G. intestinalis and Cryptosporidium spp. in 2 phases (retrospective and prospective) on a set of 482 stool samples including rare Cryptosporidium species. Besides G. intestinalis, this test could represent a rapid and reliable alternative to the modified Ziehl-Neelsen staining for the diagnosis of cryptosporidiosis (sensitivity/specificity were 89.2%/99.3% and 86.7%/100% for G. intestinalis and Cryptosporidium resp.), reducing diagnostic delays. Such strategy would also be time-saving by avoiding wet mount microscopy and concentrations steps, being particularly appropriate for laboratories having little expertise in microscopy or not able to implement molecular diagnostic methods.

Ultrasensitive and Facile Detection of MicroRNA via a Portable Pressure Meter.

The upregulation of microRNA (miRNA) is highly related with some kinds of tumor, such as breast, prostate, lung, and pancreatic cancers. Therefore, for an important tumor biomarker, the point-of-care testing (POCT) of miRNA is of significant importance and is in great demand for disease diagnosis and clinical prognoses. Herein, a POCT assay for miRNA detection was developed via a portable pressure meter. Two hairpin DNA probes, H1 and H2, were ingeniously designed and functionalized with magnetic beads (MBs) and platinum nanoparticles (PtNPs), respectively, to form MBs-H1 and PtNPs-H2 complexes. In the presence of target microRNA 21 (miR-21), the cyclic strand displacement reaction (SDR) between MBs-H1 and PtNPs-H2 was triggered to continuously form the MBs-H1/PtNPs-H2 duplex. Owing to the amplification of cyclic SDR, numerous PtNPs were enriched onto the surface of MBs to catalytically decompose H2O2 for the generation of much O2. The gas pressure value has a linear relationship with the logarithmic value of miR-21 concentration in the range of 10 fM to 10 pM. The limit of detection is 7.6 fM, which is more sensitive than that in a number of previous reports. Hairpin DNA probes and magnetic separation highly ensured the specificity and reliability. Single-base mutation was easily discriminated, and the detection of miR-21 in the serum sample achieved satisfactory result. Therefore, it offers a reliable POCT strategy for the detection of miRNA, which is of great theoretical and practical importance for POCT clinical diagnostics.

Prevalence of gestational diabetes mellitus based on various screening strategies in western Kenya: a prospective comparison of point of care diagnostic methods

BackgroundEarly diagnosis of gestational diabetes mellitus (GDM) is crucial to prevent short term delivery risks and long term effects such as cardiovascular and metabolic diseases in the mother and infant. Diagnosing GDM in Sub-Saharan Africa (SSA) however, remains sub-optimal due to associated logistical and cost barriers for resource-constrained populations. A cost-effective strategy to screen for GDM in such settings are therefore urgently required. We conducted this study to determine the prevalence of gestational diabetes mellitus (GDM) and assess utility of various GDM point of care (POC) screening strategies in a resource-constrained setting.MethodsEligible women aged ≥18 years, and between 24 and 32 weeks of a singleton pregnancy, prospectively underwent testing over two days. On day 1, a POC 1-h 50 g glucose challenge test (GCT) and a POC glycated hemoglobin (HbA1c) was assessed. On day 2, fasting blood glucose, 1-h and 2-h 75 g oral glucose tolerance test (OGTT) were determined using both venous and POC tests, along with a venous HbA1c. The International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria was used to diagnose GDM. GDM prevalence was reported with 95% confidence interval (CI). Specificity, sensitivity, positive predictive value, and negative predictive value of the various POC testing strategies were determined using IADPSG testing as the standard reference.ResultsSix hundred-sixteen eligible women completed testing procedures. GDM was diagnosed in 18 women, a prevalence of 2.9% (95% CI, 1.57% - 4.23%). Compared to IADPSG testing, POC IADPSG had a sensitivity and specificity of 55.6% and 90.6% respectively while that of POC 1-h 50 g GCT (using a diagnostic cut-off of ≥7.2 mmol/L [129.6 mg/dL]) was 55.6% and 63.9%. All other POC tests assessed showed poor sensitivity.ConclusionsPOC screening strategies though feasible, showed poor sensitivity for GDM detection in our resource-constrained population of low GDM prevalence. Studies to identify sensitive and specific POC GDM screening strategies using adverse pregnancy outcomes as end points are required.Trials registrationClinical trials.gov: NCT02978807, Registered 29 November 2016.

Lateral Flow Technology for Field-Based Applications—Basics and Advanced Developments

In terms of their ability to provide accurate information there is a traditional continuum in diagnostics that ranges from highly accurate methods requiring infrastructure and a centralized approach to testing to less accurate technologies that can be used in a decentralized or point of care testing strategy and that require little to no supporting infrastructure. Today's lateral flow assays marry the utility of a truly field deployable, simple to use technology with the high performance of many laboratory based assay formats. Advances in recent years have allowed for the extension of performance of lateral flow assays into applications that require high accuracy and sensitivity while still maintaining the advantages of the technology from the perspective of infrastructure requirements and user friendliness. This has allowed for improved application of this technology in decentralized testing environments; veterinary, medical and otherwise. The lateral flow assay, once considered less accurate and less capable than infrastructure-heavy, laboratory based formats, is being viewed more and more as a truly versatile technology, capable of more than adequate performance at all ends of the diagnostic continuum. This article discusses the state of the art in lateral flow technology and outlines the utility of the technology in a variety of field based applications.

Economic evaluations of point of care testing strategies for active tuberculosis

Point of care (POC) diagnostics are often hailed as having the potential to transform tuberculosis (TB) control efforts. However, POC testing is better conceptualized as a system of diagnosis and treatment, not simply a test that can provide rapid, deployable results. Economic evaluations may help decision makers allocate scarce resources for TB control, but evaluations of POC testing face unique challenges that include evaluating the full diagnostic system, incorporating implementation costs, translating diagnostic results into health and accounting for downstream treatment costs. For economic evaluations to reach their full potential as decision-making tools for POC testing in TB, these challenges must be understood and addressed.

Evaluation of First-Draw Whole Blood, Point-of-Care Cardiac Markers in the Context of the Universal Definition of Myocardial Infarction: A Comparison of a Multimarker Panel to Troponin Alone and to Testing in the Central Laboratory

Previous studies evaluating point-of-care testing (POCT) for cardiac biomarkers did not use current recommendations for troponin cutoff values or recognize the recent universal definition of acute myocardial infarction. Traditionally, achieving optimal sensitivity for the detection of myocardial injury on initial presentation required combining cardiac troponin and/or creatine kinase isoenzyme MB with an early marker, usually myoglobin. In recent years, the performance of central laboratory combining cardiac troponin assays has improved significantly, potentially obviating the need for a multimarker panel to achieve optimum sensitivity. To compare 2 commonly used POCT strategies to a fourth generation, central laboratory cardiac troponin T assay on first-draw specimens from patients being evaluated for acute myocardial infarction in the emergency department. The 2 strategies included a traditional POCT multimarker panel and a newer POCT method using cardiac troponin I alone. Blood specimens from 204 patients presenting to the emergency department with signs and/or symptoms of myocardial ischemia were measured on the 2 POCT systems and by a central laboratory method. The diagnosis for each patient was determined by retrospective chart review. The cardiac troponin T assasy alone was more sensitive for acute myocardial infarction than the multimarker POCT panel with equal or better specificity. When compared with a POCT troponin I, the cardiac troponin T was also more sensitive, but this difference was not significant. The POCT troponin I alone also had the same sensitivity as the multimarker panel. Testing for combining cardiac troponin alone using newer, commercially available, central laboratory or POCT assays performed with equal or greater sensitivity to acute myocardial infarction as the older, traditional, multimarker panel. In the near future, high-sensitivity, central laboratory troponins will be available for routine clinical use. As a result, the quality gap between central laboratories and older POCT methods will continue to widen, unless the performance of the POCT methods is improved.