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1.
J Clin Virol ; 165: 105521, 2023 08.
Article in English | MEDLINE | ID: covidwho-20233590

ABSTRACT

BACKGROUND: European legislation defines as "near-patient testing" (NPT) what is popularly and in other legislations specified as "point-of-care testing" (POCT). Systems intended for NPT/POCT use must be characterized by independence from operator activities during the analytic procedure. However, tools for evaluating this are lacking. We hypothesized that the variability of measurement results obtained from identical samples with a larger number of identical devices by different operators, expressed as the method-specific reproducibility of measurement results reported in External Quality Assessment (EQA) schemes, is an indicator for this characteristic. MATERIALS AND METHODS: Legal frameworks in the EU, the USA and Australia were evaluated about their requirements for NPT/POCT. EQA reproducibility of seven SARS-CoV-2-NAAT systems, all but one designated as "POCT", was calculated from variabilities in Ct values obtained from the respective device types in three different EQA schemes for virus genome detection. RESULTS: A matrix for characterizing test systems based on their technical complexity and the required operator competence was derived from requirements of the European In Vitro Diagnostic Regulation (IVDR) 2017/746. Good EQA reproducibility of the measurement results of the test systems investigated implies that different users in different locations have no recognizable influence on their measurement results. CONCLUSION: The fundamental suitability of test systems for NPT/POCT use according to IVDR can be easily verified using the evaluation matrix presented. EQA reproducibility is a specific characteristic indicating independence from operator activities of NPT/POCT assays. EQA reproducibility of other systems than those investigated here remains to be determined.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , Reproducibility of Results , COVID-19/diagnosis , Point-of-Care Systems , Nucleic Acid Amplification Techniques
2.
J Vet Intern Med ; 37(3): 1223-1232, 2023.
Article in English | MEDLINE | ID: covidwho-20233210

ABSTRACT

BACKGROUND: A point-of-care ultrasound (POCUS) protocol for evaluation of the cardiac and respiratory systems in horses does not exist. OBJECTIVES: (a) Describe the windows of a POCUS protocol for cardiorespiratory assessment of horses (CRASH); (b) Estimate the number of acoustic windows that can be acquired by a sonographer-in-training; (c) Estimate the time required to complete the protocol for specific groups of horses; (d) Describe the sonographic abnormalities detected in horses presented with cardiovascular, respiratory, or systemic disease. ANIMALS: Twenty-seven healthy horses, 14 horses competing in athletic events, and 120 horses with clinical disease. METHOD: A pocket-sized ultrasound device was used to acquire 7 sonographic cardiorespiratory windows in various clinical scenarios. The duration of the examination was timed, and images were evaluated for diagnostic quality. Abnormalities in horses with clinical disease were determined by an expert sonographer. RESULTS: The CRASH protocol could be performed in healthy and diseased horses in hospital, barn, and competition settings between 5.5 ± 0.9 (athletic horses) and 6.9 ± 1.9 min (horses with clinical disease). Thoracic windows were obtained most consistently, followed by right parasternal long-axis echocardiographic windows. Frequently detected abnormalities were pleural fluid, lung consolidation, B-lines, and moderate-to-severe left-sided heart disease. CONCLUSIONS: The CRASH protocol was feasible using a pocket-sized ultrasound device in various groups of horses, could be completed rapidly in a variety of settings, and frequently identified sonographic abnormalities when evaluated by an expert sonographer. The diagnostic accuracy, observer agreement, and utility of the CRASH protocol merit further evaluation.


Subject(s)
Point-of-Care Systems , Point-of-Care Testing , Horses , Animals , Feasibility Studies , Ultrasonography/veterinary , Ultrasonography/methods , Echocardiography/veterinary
3.
AIDS Patient Care STDS ; 37(2): 66-83, 2023 02.
Article in English | MEDLINE | ID: covidwho-20240507

ABSTRACT

To broaden access to HIV viral load monitoring (VLM), the use of blood samples from dried blood spots (DBS) or point-of-care (POC) devices, could be of great help in settings where plasma is not easily accessible. The variety of assays available makes the choice complex. This systematic review and meta-analysis aims to estimate the sensitivity and specificity of DBS and POC devices to identify patients in virological failure using World Health Organization (WHO) recommendations (viral load ≥1000 copies/mL), compared with plasma, for the assays currently available. Four databases were searched for articles, and two reviewers independently identified articles reporting sensitivity and specificity of DBS and/or POC to identify patients in virological failure. We excluded articles that used other thresholds as well as articles with a total number of participants below 50 to avoid reporting bias. Heterogeneity and factors associated with assays' performances were assessed by I2 statistics and metaregression. The protocol of this review follows the PRISMA guidelines. Out of 941 articles, 47 were included: 32 DBS evaluations and 16 POC evaluations. Overall, when using DBS, the Abbott RT HIV-1, Roche CAP-CTM, NucliSENS BioMerieux and Aptima assays presented sensitivity and specificity exceeding 85%, but reported results were highly heterogeneous. Factors associated with better performances were high volume of blood and the use of the same assay for DBS and plasma VLM. Regarding the POC devices, SAMBA I, SAMBA II, and GeneXpert devices presented high sensitivity and specificity exceeding 90%, with less heterogeneity. DBS is suitable VLM, but performances can vary greatly depending on the protocols, and should be performed in trained centers. POC is suitable for VLM with less risk of heterogeneity but is more intensive in costs and logistics.


Subject(s)
HIV Infections , HIV Seropositivity , Humans , Point-of-Care Systems , Sensitivity and Specificity , Viral Load , RNA, Viral
4.
West J Emerg Med ; 23(4): 497-504, 2022 Jun 05.
Article in English | MEDLINE | ID: covidwho-20242018

ABSTRACT

Point-of-care lung ultrasonography is an evidence-based application that may play a vital role in the care of critically ill pediatric patients. Lung ultrasonography has the advantage of being available at the patient's bedside with results superior to chest radiography and comparable to chest computed tomography for most lung pathologies. It has a steep learning curve. It can be readily performed in both advanced healthcare systems and resource-scarce settings. The purpose of this review is to discuss the basic principles of lung ultrasonography and its applications in the evaluation and treatment of critically ill pediatric patients.


Subject(s)
Critical Illness , Point-of-Care Systems , Child , Humans , Lung/diagnostic imaging , Tomography, X-Ray Computed , Ultrasonography/methods
5.
Prog Biophys Mol Biol ; 180-181: 120-130, 2023.
Article in English | MEDLINE | ID: covidwho-2321101

ABSTRACT

The widespread usage of smartphones has made accessing vast troves of data easier for everyone. Smartphones are powerful, handy, and easy to operate, making them a valuable tool for improving public health through diagnostics. When combined with other devices and sensors, smartphones have shown potential for detecting, visualizing, collecting, and transferring data, enabling rapid disease diagnosis. In resource-limited settings, the user-friendly operating system of smartphones allows them to function as a point-of-care platform for healthcare and disease diagnosis. Herein, we critically reviewed the smartphone-based biosensors for the diagnosis and detection of diseases caused by infectious human pathogens, such as deadly viruses, bacteria, and fungi. These biosensors use several analytical sensing methods, including microscopic imaging, instrumental interface, colorimetric, fluorescence, and electrochemical biosensors. We have discussed the diverse diagnosis strategies and analytical performances of smartphone-based detection systems in identifying infectious human pathogens, along with future perspectives.


Subject(s)
Biosensing Techniques , Viruses , Humans , Smartphone , Point-of-Care Systems , Bacteria
6.
Sensors (Basel) ; 23(9)2023 Apr 30.
Article in English | MEDLINE | ID: covidwho-2318020

ABSTRACT

Since its first report in 2006, magnetic particle spectroscopy (MPS)-based biosensors have flourished over the past decade. Currently, MPS are used for a wide range of applications, such as disease diagnosis, foodborne pathogen detection, etc. In this work, different MPS platforms, such as dual-frequency and mono-frequency driving field designs, were reviewed. MPS combined with multi-functional magnetic nanoparticles (MNPs) have been extensively reported as a versatile platform for the detection of a long list of biomarkers. The surface-functionalized MNPs serve as nanoprobes that specifically bind and label target analytes from liquid samples. Herein, an analysis of the theories and mechanisms that underlie different MPS platforms, which enable the implementation of bioassays based on either volume or surface, was carried out. Furthermore, this review draws attention to some significant MPS platform applications in the biomedical and biological fields. In recent years, different kinds of MPS point-of-care (POC) devices have been reported independently by several groups in the world. Due to the high detection sensitivity, simple assay procedures and low cost per run, the MPS POC devices are expected to become more widespread in the future. In addition, the growth of telemedicine and remote monitoring has created a greater demand for POC devices, as patients are able to receive health assessments and obtain results from the comfort of their own homes. At the end of this review, we comment on the opportunities and challenges for POC devices as well as MPS devices regarding the intensely growing demand for rapid, affordable, high-sensitivity and user-friendly devices.


Subject(s)
Biosensing Techniques , Point-of-Care Systems , Humans , Biosensing Techniques/methods , Magnetics , Spectrum Analysis , Magnetic Phenomena
7.
J Intensive Care Med ; 38(6): 566-570, 2023 Jun.
Article in English | MEDLINE | ID: covidwho-2317252

ABSTRACT

Keeping up with the latest developments in the point-of-care ultrasound (POCUS) literature is challenging, as with any area of medicine. Our group of POCUS experts has selected 10 influential papers from the past 12 months and provided a short summary of each. We hope to provide emergency physicians, intensivists, and other acute care providers with a succinct update concerning some key areas of ultrasound interest.


Subject(s)
Point-of-Care Systems , Point-of-Care Testing , Humans , Ultrasonography
8.
J Clin Virol ; 164: 105492, 2023 07.
Article in English | MEDLINE | ID: covidwho-2319271

ABSTRACT

Historically, the diagnosis of viral infections has been accomplished using a combination of laboratory-based methods, including culture, serology, antigen-based tests, and molecular (e.g., real-time PCR) assays. Although these methods provide an accurate way to detect viral pathogens, testing in a centralized laboratory may delay results, which could impact patient diagnosis and management. Point-of-care tests, including antigen- and molecular-based assays, have been developed to assist with the timely diagnosis of several viral infections, such as influenza, respiratory syncytial virus, and COVID-19. Despite the ability of point-of-care tests to provide rapid results (i.e., <30 min), there are issues to consider prior to their routine use, including test performance and specific regulatory requirements. This review will provide a summary of the regulatory landscape of point-of-care tests for viral infections in the United States, and address important considerations such as site certification, training and inspection readiness.


Subject(s)
COVID-19 , Respiratory Syncytial Virus, Human , Virus Diseases , Humans , United States , COVID-19/diagnosis , Molecular Diagnostic Techniques/methods , Point-of-Care Testing , Virus Diseases/diagnosis , Respiratory Syncytial Virus, Human/genetics , Sensitivity and Specificity , Point-of-Care Systems
9.
Biosensors (Basel) ; 13(2)2023 Jan 29.
Article in English | MEDLINE | ID: covidwho-2309398

ABSTRACT

With the move of molecular tests from diagnostic labs to on-site testing becoming more common, there is a sudden rise in demand for nucleic acid-based diagnostic tools that are selective, sensitive, flexible to terrain changes, and cost-effective to assist in point-of-care systems for large-scale screening and to be used in remote locations in cases of outbreaks and pandemics. CRISPR-based biosensors comprise a promising new approach to nucleic acid detection, which uses Cas effector proteins (Cas9, Cas12, and Cas13) as extremely specialized identification components that may be used in conjunction with a variety of readout approaches (such as fluorescence, colorimetry, potentiometry, lateral flow assay, etc.) for onsite analysis. In this review, we cover some technical aspects of integrating the CRISPR Cas system with traditional biosensing readout methods and amplification technologies such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA) and continue to elaborate on the prospects of the developed biosensor in the detection of some major viral and bacterial diseases. Within the scope of this article, we also discuss the recent COVID pandemic and the numerous CRISPR biosensors that have undergone development since its advent. Finally, we discuss some challenges and future prospects of CRISPR Cas systems in point-of-care testing.


Subject(s)
Biosensing Techniques , COVID-19 , Nucleic Acids , Humans , Point-of-Care Systems , Point-of-Care Testing , Biological Assay , Nucleic Acid Amplification Techniques , COVID-19 Testing
10.
J Virol Methods ; 315: 114714, 2023 05.
Article in English | MEDLINE | ID: covidwho-2308074

ABSTRACT

We present the point-of-care (POC) molecular diagnostic solution, evaluated during COVID-19 pandemic caused by SARS-CoV-2 (Dec 2021). The POC comprised of a complete platform from self-sampling to RT-PCR testing of SARS-CoV-2 and its variants on portable Compact Q Real time polymerase chain reaction system. The multiplex assay was designed to target S, ORF1, and N genes of SARS-CoV-2 genome in a single tube with RNaseP as endogenous internal control. The present POC enables high accuracy (>95%) and high-throughput testing with a turnaround time of 45 min. It provides a unique platform from self-sample collection to report generation with rapid protocol, pipette and expert-free operation, long shelf-life stability and room temperature storage which enable to increase the efficiency of molecular testing. This novel test named "CoviSwift™ COVID-19 S PLUS RAPID PCR KIT" has been approved by CDSCO, Indian National Regulatory Authority, India, and is in use for clinical settings in India.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/diagnosis , Point-of-Care Systems , Reverse Transcriptase Polymerase Chain Reaction , Pandemics , Sensitivity and Specificity , Real-Time Polymerase Chain Reaction , COVID-19 Testing
13.
J Opt Soc Am A Opt Image Sci Vis ; 40(4): C1-C7, 2023 Apr 01.
Article in English | MEDLINE | ID: covidwho-2302045

ABSTRACT

Since the global pandemic of SARS-CoV-2, people's health and the economic support of their countries have been seriously affected. It was necessary to develop a low-cost and faster diagnostic tool that allows the evaluation of symptomatic patients. Point-of-care testing and point-of-need testing systems have been recently developed to solve these drawbacks, providing accurate and rapid diagnostics at field level or at the site of outbreaks. In this work, a bio-photonic device has been developed for the diagnosis of COVID-19. The device is used with an isothermal system (Easy Loop Amplification based) for the detection of SARS-CoV-2. The performance of the device was evaluated in the detection of a SARS-CoV-2 RNA sample panel, showing an analytical sensitivity comparable to the reference method of quantitative reverse transcription polymerase chain reaction used commercially. In addition, the device was mainly built with simple and low-cost components; therefore, it is possible to obtain a high-efficiency and low-cost instrument. The device excites the sample to be analyzed with a semiconductor laser with a specific wavelength, thus triggering spontaneous emission of the fluorophore bound to the specific probe. The emitted fluorescence is suitably managed by using interferential filters. Under these conditions, a signal is registered and, depending on this level, defines the case as positive or negative. All the analysis is done autonomously inside the developed device through an integrated control system, and it is connected to a portable device to show the results wirelessly.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/diagnosis , Point-of-Care Systems , RNA, Viral/genetics , Sensitivity and Specificity , DNA
14.
J Hosp Med ; 18(5): 413-423, 2023 05.
Article in English | MEDLINE | ID: covidwho-2302019

ABSTRACT

BACKGROUND: Identifying COVID-19 patients at the highest risk of poor outcomes is critical in emergency department (ED) presentation. Sepsis risk stratification scores can be calculated quickly for COVID-19 patients but have not been evaluated in a large cohort. OBJECTIVE: To determine whether well-known risk scores can predict poor outcomes among hospitalized COVID-19 patients. DESIGNS, SETTINGS, AND PARTICIPANTS: A retrospective cohort study of adults presenting with COVID-19 to 156 Hospital Corporation of America (HCA) Healthcare EDs, March 2, 2020, to February 11, 2021. INTERVENTION: Quick Sequential Organ Failure Assessment (qSOFA), Shock Index, National Early Warning System-2 (NEWS2), and quick COVID-19 Severity Index (qCSI) at presentation. MAIN OUTCOME AND MEASURES: The primary outcome was in-hospital mortality. Secondary outcomes included intensive care unit (ICU) admission, mechanical ventilation, and vasopressors receipt. Patients scored positive with qSOFA ≥ 2, Shock Index > 0.7, NEWS2 ≥ 5, and qCSI ≥ 4. Test characteristics and area under the receiver operating characteristics curves (AUROCs) were calculated. RESULTS: We identified 90,376 patients with community-acquired COVID-19 (mean age 64.3 years, 46.8% female). 17.2% of patients died in-hospital, 28.6% went to the ICU, 13.7% received mechanical ventilation, and 13.6% received vasopressors. There were 3.8% qSOFA-positive, 45.1% Shock Index-positive, 49.8% NEWS2-positive, and 37.6% qCSI-positive at ED-triage. NEWS2 exhibited the highest AUROC for in-hospital mortality (0.593, confidence interval [CI]: 0.588-0.597), ICU admission (0.602, CI: 0.599-0.606), mechanical ventilation (0.614, CI: 0.610-0.619), and vasopressor receipt (0.600, CI: 0.595-0.604). CONCLUSIONS: Sepsis severity scores at presentation have low discriminative power to predict outcomes in COVID-19 patients and are not reliable for clinical use. Severity scores should be developed using features that accurately predict poor outcomes among COVID-19 patients to develop more effective risk-based triage.


Subject(s)
COVID-19 , Sepsis , Adult , Humans , Female , Middle Aged , Male , COVID-19/diagnosis , Retrospective Studies , Point-of-Care Systems , Organ Dysfunction Scores , Emergency Service, Hospital , ROC Curve , Prognosis , Hospital Mortality , Intensive Care Units
15.
PLoS One ; 18(4): e0284748, 2023.
Article in English | MEDLINE | ID: covidwho-2300386

ABSTRACT

BACKGROUND: Lung point-of-care ultrasonography (L-POCUS) is highly effective in detecting pulmonary peripheral patterns and may allow early identification of patients who are likely to develop an acute respiratory distress syndrome (ARDS). We hypothesized that L-POCUS performed within the first 48 hours of non-critical patients with suspected COVID-19 would identify those with a high-risk of worsening. METHODS: POCUSCO was a prospective, multicenter study. Non-critical adult patients who presented to the emergency department (ED) for suspected or confirmed COVID-19 were included and had L-POCUS performed within 48 hours following ED presentation. The lung damage severity was assessed using a previously developed score reflecting both the extension and the intensity of lung damage. The primary outcome was the rate of patients requiring intubation or who died within 14 days following inclusion. RESULTS: Among 296 patients, 8 (2.7%) met the primary outcome. The area under the curve (AUC) of L-POCUS was 0.80 [95%CI:0.60-0.94]. The score values which achieved a sensibility >95% in defining low-risk patients and a specificity >95% in defining high-risk patients were <1 and ≥16, respectively. The rate of patients with an unfavorable outcome was 0/95 (0%[95%CI:0-3.9]) for low-risk patients (score = 0), 4/184 (2.17%[95%CI:0.8-5.5]) for intermediate-risk patients (score 1-15) and 4/17 (23.5%[95%CI:11.4-42.4]) for high-risk patients (score ≥16). In confirmed COVID-19 patients (n = 58), the AUC of L-POCUS was 0.97 [95%CI:0.92-1.00]. CONCLUSION: L-POCUS performed within the first 48 hours following ED presentation allows risk-stratification of patients with non-severe COVID-19.


Subject(s)
COVID-19 , Adult , Humans , COVID-19/diagnostic imaging , Point-of-Care Systems , Prospective Studies , Ultrasonography , Emergency Service, Hospital , Risk Assessment
16.
BMC Prim Care ; 24(1): 96, 2023 04 11.
Article in English | MEDLINE | ID: covidwho-2299748

ABSTRACT

BACKGROUND: Due to their fast turnaround time and user-friendliness, point-of-care tests (POCTs) possess a great potential in primary care. The purpose of the study was to assess general practitioners' (GPs) perspectives on POCT use in German primary care, including utilization, limitations and requirements. METHODS: We conducted a cross-sectional survey study among GPs in Germany (federal states of Thuringia, Bremen and Bavaria (Lower Franconia), study period: 04/22-06/2022). RESULTS: From 2,014 GPs reached, 292 participated in our study (response rate: 14.5%). The median number of POCTs used per GP was 7.0 (IQR: 5.0-8.0). Six POCTs are used by the majority of surveyed GPs (> 50%): urine dipstick tests (99%), glucose (urine [91%] and plasma [69%]), SARS-CoV-2 (80%), urine microalbumin (77%), troponin I/T (74%) and prothrombin time / international normalized ratio (65%). The number of utilized POCTs did not differ between GP practice type (p = 0.307) and population size of GP practice location (p = 0.099). The great majority of participating German GPs (93%) rated POCTs as useful diagnostic tools in the GP practice. GPs ranked immediate decisions on patient management and the increase in diagnostic certainty as the most important reasons for performing POCTs. The most frequently reported limitations of POCT use in the GP practice were economic aspects (high costs and inadequate reimbursement), concerns regarding diagnostic accuracy, and difficulties to integrate POCT-testing into practice routines (e.g. time and personnel expenses). CONCLUSION: Although participating German GPs generally perceive POCTs as useful diagnostic tools and numerous POCTs are available, several test-related and contextual factors contribute to the relatively low utilization of POCTs in primary care.


Subject(s)
COVID-19 , General Practitioners , Humans , Point-of-Care Systems , Cross-Sectional Studies , SARS-CoV-2 , Point-of-Care Testing , Primary Health Care , COVID-19 Testing
17.
Lancet ; 400(10356): 887-895, 2022 09 17.
Article in English | MEDLINE | ID: covidwho-2269958

ABSTRACT

BACKGROUND: Timely diagnosis and treatment of HIV is crucial in HIV-exposed infants to prevent the high rates of mortality seen during the first 2 years of life if HIV is untreated. However, challenges with sample transportation, testing, and result delivery to caregivers have led to long delays in treatment initiation. We aimed to compare the clinical effect of point-of-care HIV testing versus laboratory-based testing (standard of care) in HIV-exposed infants. METHODS: We did a systematic review and meta-analysis and searched PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Conference Proceedings Citation Index-Science, and WHO Global Index Medicus, from Jan 1, 2014, to Aug 31, 2020. Studies were included if they pertained to the use of point-of-care nucleic acid testing for infant HIV diagnosis, had a laboratory-based nucleic acid test as the comparator or standard of care against the index test (same-day point-of-care testing), evaluated clinical outcomes when point-of-care testing was used, and included HIV-exposed infants aged younger than 2 years. Studies were excluded if they did not use a laboratory-based comparator, a nucleic acid test that had been approved by a stringent regulatory authority, or diagnostic-accuracy or performance evaluations (eg, no clinical outcomes included). Reviews, non-research letters, commentaries, and editorials were also excluded. The risk of bias was evaluated using the ROBINS-I framework. Data were extracted from published reports. Data from all studies were analysed using frequency statistics to describe the overall populations evaluated and their results. Key outcomes were time to result delivery and antiretroviral therapy initiation, and proportion of HIV-positive infants initiated on antiretroviral therapy within 60 days after sample collection. FINDINGS: 164 studies were identified by the search and seven were included in the analysis, comprising 37 377 infants in total across 15 countries, including 25 170 (67%) who had point-of-care HIV testing and 12 207 (33%) who had standard-of-care testing. The certainty of evidence was high. Same-day point-of-care testing led to a significantly shorter time between sample collection and result delivery to caregivers compared with standard-of-care testing (median 0 days [95% CI 0-0] vs 35 days [35-37]). Time from sample collection to antiretroviral therapy initiation in infants found to be HIV-positive was significantly lower with point-of-care testing compared with standard of care (median 0 days [95% CI 0-1] vs 40 days [36-44]). When each study's result was weighted equally, 90·3% (95% CI 76·7-96·5) of HIV-positive infants diagnosed using point-of-care testing had started antiretroviral therapy within 60 days of sample collection, compared with only 51·6% (27·1-75·7) who had standard-of-care testing (odds ratio 8·74 [95% CI 6·6-11·6]; p<0·0001). INTERPRETATION: Overall, the certainty of the evidence in this analysis was rated as high for the primary outcomes related to result delivery and treatment initiation, with no serious risk of bias, inconsistency, indirectness, or imprecision. In HIV-exposed infants, same-day point-of-care HIV testing was associated with significantly improved time to result delivery, time to antiretroviral therapy initiation, and proportion of HIV-positive infants starting antiretroviral therapy within 60 days compared with standard of care. FUNDING: The Bill & Melinda Gates Foundation.


Subject(s)
HIV Infections , Nucleic Acids , Early Diagnosis , HIV Infections/diagnosis , HIV Infections/drug therapy , HIV Infections/prevention & control , Humans , Infant , Nucleic Acids/therapeutic use , Point-of-Care Systems , Point-of-Care Testing
18.
Cochrane Database Syst Rev ; 7: CD013705, 2022 07 22.
Article in English | MEDLINE | ID: covidwho-2257281

ABSTRACT

BACKGROUND: Accurate rapid diagnostic tests for SARS-CoV-2 infection would be a useful tool to help manage the COVID-19 pandemic. Testing strategies that use rapid antigen tests to detect current infection have the potential to increase access to testing, speed detection of infection, and inform clinical and public health management decisions to reduce transmission. This is the second update of this review, which was first published in 2020. OBJECTIVES: To assess the diagnostic accuracy of rapid, point-of-care antigen tests for diagnosis of SARS-CoV-2 infection. We consider accuracy separately in symptomatic and asymptomatic population groups. Sources of heterogeneity investigated included setting and indication for testing, assay format, sample site, viral load, age, timing of test, and study design. SEARCH METHODS: We searched the COVID-19 Open Access Project living evidence database from the University of Bern (which includes daily updates from PubMed and Embase and preprints from medRxiv and bioRxiv) on 08 March 2021. We included independent evaluations from national reference laboratories, FIND and the Diagnostics Global Health website. We did not apply language restrictions. SELECTION CRITERIA: We included studies of people with either suspected SARS-CoV-2 infection, known SARS-CoV-2 infection or known absence of infection, or those who were being screened for infection. We included test accuracy studies of any design that evaluated commercially produced, rapid antigen tests. We included evaluations of single applications of a test (one test result reported per person) and evaluations of serial testing (repeated antigen testing over time). Reference standards for presence or absence of infection were any laboratory-based molecular test (primarily reverse transcription polymerase chain reaction (RT-PCR)) or pre-pandemic respiratory sample. DATA COLLECTION AND ANALYSIS: We used standard screening procedures with three people. Two people independently carried out quality assessment (using the QUADAS-2 tool) and extracted study results. Other study characteristics were extracted by one review author and checked by a second. We present sensitivity and specificity with 95% confidence intervals (CIs) for each test, and pooled data using the bivariate model. We investigated heterogeneity by including indicator variables in the random-effects logistic regression models. We tabulated results by test manufacturer and compliance with manufacturer instructions for use and according to symptom status. MAIN RESULTS: We included 155 study cohorts (described in 166 study reports, with 24 as preprints). The main results relate to 152 evaluations of single test applications including 100,462 unique samples (16,822 with confirmed SARS-CoV-2). Studies were mainly conducted in Europe (101/152, 66%), and evaluated 49 different commercial antigen assays. Only 23 studies compared two or more brands of test. Risk of bias was high because of participant selection (40, 26%); interpretation of the index test (6, 4%); weaknesses in the reference standard for absence of infection (119, 78%); and participant flow and timing 41 (27%). Characteristics of participants (45, 30%) and index test delivery (47, 31%) differed from the way in which and in whom the test was intended to be used. Nearly all studies (91%) used a single RT-PCR result to define presence or absence of infection. The 152 studies of single test applications reported 228 evaluations of antigen tests. Estimates of sensitivity varied considerably between studies, with consistently high specificities. Average sensitivity was higher in symptomatic (73.0%, 95% CI 69.3% to 76.4%; 109 evaluations; 50,574 samples, 11,662 cases) compared to asymptomatic participants (54.7%, 95% CI 47.7% to 61.6%; 50 evaluations; 40,956 samples, 2641 cases). Average sensitivity was higher in the first week after symptom onset (80.9%, 95% CI 76.9% to 84.4%; 30 evaluations, 2408 cases) than in the second week of symptoms (53.8%, 95% CI 48.0% to 59.6%; 40 evaluations, 1119 cases). For those who were asymptomatic at the time of testing, sensitivity was higher when an epidemiological exposure to SARS-CoV-2 was suspected (64.3%, 95% CI 54.6% to 73.0%; 16 evaluations; 7677 samples, 703 cases) compared to where COVID-19 testing was reported to be widely available to anyone on presentation for testing (49.6%, 95% CI 42.1% to 57.1%; 26 evaluations; 31,904 samples, 1758 cases). Average specificity was similarly high for symptomatic (99.1%) or asymptomatic (99.7%) participants. We observed a steady decline in summary sensitivities as measures of sample viral load decreased. Sensitivity varied between brands. When tests were used according to manufacturer instructions, average sensitivities by brand ranged from 34.3% to 91.3% in symptomatic participants (20 assays with eligible data) and from 28.6% to 77.8% for asymptomatic participants (12 assays). For symptomatic participants, summary sensitivities for seven assays were 80% or more (meeting acceptable criteria set by the World Health Organization (WHO)). The WHO acceptable performance criterion of 97% specificity was met by 17 of 20 assays when tests were used according to manufacturer instructions, 12 of which demonstrated specificities above 99%. For asymptomatic participants the sensitivities of only two assays approached but did not meet WHO acceptable performance standards in one study each; specificities for asymptomatic participants were in a similar range to those observed for symptomatic people. At 5% prevalence using summary data in symptomatic people during the first week after symptom onset, the positive predictive value (PPV) of 89% means that 1 in 10 positive results will be a false positive, and around 1 in 5 cases will be missed. At 0.5% prevalence using summary data for asymptomatic people, where testing was widely available and where epidemiological exposure to COVID-19 was suspected, resulting PPVs would be 38% to 52%, meaning that between 2 in 5 and 1 in 2 positive results will be false positives, and between 1 in 2 and 1 in 3 cases will be missed. AUTHORS' CONCLUSIONS: Antigen tests vary in sensitivity. In people with signs and symptoms of COVID-19, sensitivities are highest in the first week of illness when viral loads are higher. Assays that meet appropriate performance standards, such as those set by WHO, could replace laboratory-based RT-PCR when immediate decisions about patient care must be made, or where RT-PCR cannot be delivered in a timely manner. However, they are more suitable for use as triage to RT-PCR testing. The variable sensitivity of antigen tests means that people who test negative may still be infected. Many commercially available rapid antigen tests have not been evaluated in independent validation studies. Evidence for testing in asymptomatic cohorts has increased, however sensitivity is lower and there is a paucity of evidence for testing in different settings. Questions remain about the use of antigen test-based repeat testing strategies. Further research is needed to evaluate the effectiveness of screening programmes at reducing transmission of infection, whether mass screening or targeted approaches including schools, healthcare setting and traveller screening.


Subject(s)
COVID-19 , COVID-19/diagnosis , COVID-19 Testing , Humans , Pandemics , Point-of-Care Systems , SARS-CoV-2 , Sensitivity and Specificity
19.
Biosensors (Basel) ; 12(9)2022 Aug 24.
Article in English | MEDLINE | ID: covidwho-2252617

ABSTRACT

Isothermal amplification (IA) is a nucleic acid amplification technology (NAAT) that has contributed significantly to the healthcare system. The combination of NAAT with a suitable detection platform resulted in higher sensitivity, specificity, and rapid disease diagnosis. Traditional NAAT, such as polymerase chain reaction (PCR), is widely applied in the general healthcare system but is rarely accessed in resource-limited hospitals. Some IA methods provide a rapid, sensitive, specific, and simple method for disease diagnosis. However, not all IA techniques have been regularly used in clinical applications because different biomarkers and sample types affect either the enzyme in the IA system or sample preparation. This review focuses on the application of some IA techniques that have been applied in the medical field and have the potential for use at points of care.


Subject(s)
Nucleic Acid Amplification Techniques , Nucleic Acids , Nucleic Acid Amplification Techniques/methods , Point-of-Care Systems , Polymerase Chain Reaction , Sensitivity and Specificity , Technology
20.
BMC Emerg Med ; 23(1): 28, 2023 03 14.
Article in English | MEDLINE | ID: covidwho-2285110

ABSTRACT

INTRODUCTION: Bacterial infections are frequently seen in the emergency department (ED), but can be difficult to distinguish from viral infections and some non-infectious diseases. Common biomarkers such as c-reactive protein (CRP) and white blood cell (WBC) counts fail to aid in the differential diagnosis. Neutrophil CD64 (nCD64), an IgG receptor, is suggested to be more specific for bacterial infections. This study investigated if nCD64 can distinguish bacterial infections from other infectious and non-infectious diseases in the ED. METHODS: All COVID-19 suspected patients who visited the ED and for which a definitive diagnosis was made, were included. Blood was analyzed using an automated flow cytometer within 2 h after presentation. Patients were divided into a bacterial, viral, and non-infectious disease group. We determined the diagnostic value of nCD64 and compared this to those of CRP and WBC counts. RESULTS: Of the 291 patients presented at the ED, 182 patients were included with a definitive diagnosis (bacterial infection n = 78; viral infection n = 64; non-infectious disease n = 40). ROC-curves were plotted, with AUCs of 0.71 [95%CI: 0.64-0.79], 0.77 [0.69-0.84] and 0.64 [0.55-0.73] for nCD64, WBC counts and CRP, respectively. In the bacterial group, nCD64 MFI was significantly higher compared to the other groups (p < 0.01). A cut-off of 9.4 AU MFI for nCD64 corresponded with a positive predictive value of 1.00 (sensitivity of 0.27, a specificity of 1.00, and an NPV of 0.64). Furthermore, a diagnostic algorithm was constructed which can serve as an example of what a future biomarker prediction model could look like. CONCLUSION: For patients in the ED presenting with a suspected infection, nCD64 measured with automatic flow cytometry, has a high specificity and positive predictive value for diagnosing a bacterial infection. However, a low nCD64 cannot rule out a bacterial infection. For future purposes, nCD64 should be combined with additional tests to form an algorithm that adequately diagnoses infectious diseases.


Subject(s)
Bacterial Infections , COVID-19 , Noncommunicable Diseases , Humans , Neutrophils , Point-of-Care Systems , COVID-19/diagnosis , Biomarkers , Bacterial Infections/diagnosis , Bacterial Infections/metabolism , C-Reactive Protein/analysis , Emergency Service, Hospital , Diagnostic Tests, Routine , COVID-19 Testing
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