Performance of point-of care molecular and antigen-based tests for SARS-CoV-2: a living systematic review and meta-analysis

BACKGROUND

Molecular and antigen point-of-care tests (POCTs) have augmented our ability to rapidly identify and manage SARS-CoV-2 infection. However, their clinical performance varies among individual studies.

OBJECTIVES

The evaluation of the performance of molecular and antigen-based POCTs in confirmed, suspected, or probable COVID-19 cases compared with that of laboratory-based RT-PCR in real-life settings.

DATA SOURCES

MEDLINE/PubMed, Scopus, Embase, Web of Science, Cochrane Library, Cochrane COVID-19 study register, and COVID-19 Living Evidence Database from the University of Bern.

STUDY ELIGIBILITY CRITERIA

Peer-reviewed or preprint observational studies or randomized controlled trials that evaluated any type of commercially available antigen and/or molecular POCTs for SARS-CoV-2, including multiplex PCR panels, approved by the United States Food and Drug Administration, with Emergency Use Authorization, and/or marked with Conformitè Europëenne from European Commission/European Union.

PARTICIPANTS

Close contacts and/or patients with symptomatic and/or asymptomatic confirmed, suspected, or probable COVID-19 infection of any age.

TEST/S

Molecular and/or antigen-based SARS-CoV-2 POCTs.

REFERENCE STANDARD

Laboratory-based SARS-CoV-2 RT-PCR.

ASSESSMENT OF RISK OF BIAS

Eligible studies were subjected to quality-control and risk-of-bias assessment using the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

METHODS OF DATA SYNTHESIS

Summary sensitivities and specificities with their 95% CIs were estimated using a bivariate model. Subgroup analysis was performed when at least three studies informed the outcome.

RESULTS

A total of 123 eligible publications (97 and 26 studies assessing antigen-based and molecular POCTs, respectively) were retrieved from 4674 initial records. The pooled sensitivity and specificity for 13 molecular-based POCTs were 92.8% (95% CI, 88.9-95.4%) and 97.6% (95% CI, 96.6-98.3%), respectively. The sensitivity of antigen-based POCTs pooled from 138 individual evaluations was considerably lower than that of molecular POCTs; the pooled sensitivity and specificity rates were 70.6% (95% CI, 67.2-73.8%) and 98.9% (95% CI, 98.5-99.2%), respectively.

DISCUSSION

Further studies are needed to evaluate the performance of molecular and antigen-based POCTs in underrepresented patient subgroups and different respiratory samples.

Allergen extract- and component-based diagnostics in children of the ALLIANCE asthma cohort

BACKGROUND

Current in vitro allergen-specific IgE (sIgE) detection assays measure IgE against allergen extracts or molecules in a single- or multiplex approach. Direct comparisons of the performance of such assays among young children with common presentations of allergic diseases regardless of sensitization status are largely missing.

OBJECTIVES

The aim of this study was a comparison of the analytical and diagnostic performance for common clinical questions of three commonly used technologies which rely upon different laboratory methodologies among children of the All Age Asthma (ALLIANCE) cohort (clinicaltrials.gov: NCT02496468).

METHODS

Sera from 106 paediatric study participants (mean age 4 years) were assessed for the presence of sIgE by means of the ImmunoCAP™ sx1 and fx5 mixes, the ImmunoCAP ISAC™ 112 microarray and a Euroline™ panel.

RESULTS

Total and negative concordance was high (>82%->89%), while positive concordance varied considerably (0%-100%) but was also >50% for the most common sensitizations analysed (house dust mite and birch). All three test systems showed good sensitivity and specificity (AUC consistently > 0.7). However, no significant differences with regard to identifying sIgE sensitizations associated with symptoms in children with suspected pollen- or dust-triggered wheeze or presenting with symptoms of allergic rhinoconjunctivitis or food allergy were detected. Extending the number of allergens did not change the similar performance of the three assay systems.

CONCLUSION AND CLINICAL RELEVANCE

Among young children, the three sIgE assays showed good analytical and diagnostic concordance. Our results caution that the identification of larger numbers of sensitizations by more comprehensive multiplex approaches may not improve the clinical utility of sIgE testing in this age group.

Differential Efficacy of Novel Antiviral Substances in 3D and Monolayer Cell Culture

Repurposing of approved drugs that target host functions also important for virus replication promises to overcome the shortage of antiviral therapeutics. Mostly, virus biology including initial screening of antivirals is studied in conventional monolayer cells. The biology of these cells differs considerably from infected tissues. 3D culture models with characteristics of human tissues may reflect more realistically the in vivo events during infection. We screened first, second, and third generation epidermal growth factor receptor (EGFR)-inhibitors with different modes of action and the EGFR-blocking monoclonal antibody cetuximab in a 3D cell culture infection model with primary human keratinocytes and cowpox virus (CPXV) for antiviral activity. Antiviral activity of erlotinib and osimertinib was nearly unaffected by the cultivation method similar to the virus-directed antivirals tecovirimat and cidofovir. In contrast, the host-directed inhibitors afatinib and cetuximab were approx. 100-fold more efficient against CPXV in the 3D infection model, similar to previous results with gefitinib. In summary, inhibition of EGFR-signaling downregulates virus replication comparable to established virus-directed antivirals. However, in contrast to virus-directed inhibitors, in vitro efficacy of host-directed antivirals might be seriously affected by cell cultivation. Results obtained for afatinib and cetuximab suggest that screening of such drugs in standard monolayer culture might underestimate their potential as antivirals.

Current and Future Point-of-Care Tests for Emerging and New Respiratory Viruses and Future Perspectives

The availability of pathogen-specific treatment options for respiratory tract infections (RTIs) increased the need for rapid diagnostic tests. Besides, retrospective studies, improved lab-based detection methods and the intensified search for new viruses since the beginning of the twenty-first century led to the discovery of several novel respiratory viruses. Among them are human bocavirus (HBoV), human coronaviruses (HCoV-HKU1, -NL63), human metapneumovirus (HMPV), rhinovirus type C (RV-C), and human polyomaviruses (KIPyV, WUPyV). Additionally, new viruses like SARS coronavirus (SARS-CoV), MERS coronavirus (MERS-CoV), novel strains of influenza virus A and B, and (most recently) SARS coronavirus 2 (SARS-CoV-2) have emerged. Although clinical presentation may be similar among different viruses, associated symptoms may range from a mild cold to a severe respiratory illness, and thus require a fast and reliable diagnosis. The increasing number of commercially available rapid point-of-care tests (POCTs) for respiratory viruses illustrates both the need for this kind of tests but also the problem, i.e., that the majority of such assays has significant limitations. In this review, we summarize recently published characteristics of POCTs and discuss their implications for the treatment of RTIs. The second key aspect of this work is a description of new and innovative diagnostic techniques, ranging from biosensors to novel portable and current lab-based nucleic acid amplification methods with the potential future use in point-of-care settings. While prototypes for some methods already exist, other ideas are still experimental, but all of them give an outlook of what can be expected as the next generation of POCTs.

Virus-Induced T Cell-Mediated Heterologous Immunity and Vaccine Development

Heterologous immunity (H.I.) is a consequence of an encounter with a specific antigen, which can alter the subsequent immune response to a different antigen. This can happen at the innate immune system level—often called trained immunity or innate immune memory—and/or at the adaptive immune system level involving T memory cells and antibodies. Viruses may also induce T cell-mediated H.I., which can confer protection or drive immunopathology against other virus subtypes, related or unrelated viruses, other pathogens, auto- or allo-antigens. It is important to understand the underlying mechanisms for the development of antiviral “universal” vaccines and broader T cell responses rather than just subtype-specific antibody responses as in the case of influenza. Furthermore, knowledge about determinants of vaccine-mediated H.I. may inform public health policies and provide suggestions for repurposing existing vaccines. Here, we introduce H.I. and provide an overview of evidence on virus- and antiviral vaccine-induced T cell-mediated cross-reactive responses. We also discuss the factors influencing final clinical outcome of virus-mediated H.I. as well as non-specific beneficial effects of live attenuated antiviral vaccines such as measles and vaccinia. Available epidemiological and mechanistic data have implications both for the development of new vaccines and for personalized vaccinology, which are presented. Finally, we formulate future research priorities and opportunities.

Is bladder voiding efficiency useful to evaluate voiding function in women older than 65 years?

AIMS

The aims of the study were to evaluate the reproducibility of bladder voiding efficiency (BVE) between free flow (FF) and intubated flow(IF) in old women, and to search for a relationship of this index with complaint and urodynamic diagnosis.

METHODS

Urodynamic tracings of non-neurologic women referred for investigation of various lower urinary tract symptoms (LUTS) were analyzed. Urodynamic study included one FF followed by one cystometry and IF. Post void residual volume (PVR) was measured using a Bladder-scan. Exclusion criteria were voided volume<100ml and prolapse of grade>2.

RESULTS

One hundred and ninety women met the study criteria. The mean age was 74±6 years [65-96years]. The main complaint was urinary incontinence: stress (26), urge (53) and mixed (56). Forty-four women had various complaints without incontinence. Overall BVE IF (77.6±25.8) was significantly lower than BVE FF (90.4±15.3) (P<.0001). Age sub-groups stratification led similar results. BVE IF was significantly lower than BVE FF in women with incontinence whatever the cause. Urodynamic diagnosis was posed according to the ICS/IUGA recommendations and 2 sub-groups defined according with involvement of detrusor. BVE IF was significantly lower than BVE FF for detrusor dysfunction, except for detrusor overactivity.

CONCLUSION

In this large cohort of old non-neurologic women studied urodynamically for a variety of LUTS, BVE is higher when evaluated from a FF whatever age and for complaint of urinary incontinence. In addition, a low BVE value from an IF may suggest a detrusor dysfunction.

LEVEL OF EVIDENCE

4.

Usefulness of an algebraic fitting of nomograms allowing evaluation detrusor contractility in women

AIMS

Nomograms based on Valentini-Besson-Nelson (VBN) model implying only 3 measurements (filling bladder volume, maximum flow-rate [Q_max] and detrusor pressure at Q_max) were recently developed to evaluate detrusor contractility (k) and urethral obstruction (U) in women. As their algebraic fitting leads to fast evaluations (Excel^® software), our aims were applications to populations of non-neurologic women without and with bladder outlet obstruction (BOO).

METHODS

The software was applied to measurements obtained during pressure flow studies. Hidden hypothesis of nomograms were no significant contribution of abdominal pressure between onset of flow and Q_max and standard nervous excitations until Q_max. Studied populations were 202 women without symptom suggestive of obstruction and 125 women with proven anatomical urethral obstruction who underwent urodynamic study.

RESULTS

For non-obstructed women, a good agreement was found between the values of k and U obtained using nomograms or a complete VBN analysis of the recorded curves. Whatever the obstructive status, there was a good correlation between the value of k and U. Evolution with ageing was similar with higher values of k and U in the BOO group. Curves k(age) and U(age) gave coefficients allowing an age adjustment. The high k value in the detrusor overactive (DO) group was consistent with a similar effect to that of BOO on the detrusor.

CONCLUSION

Evaluation of detrusor contractility (k) and urethral obstruction (U) can be obtained from the point of Q_max during pressure-flow study. Evolution with ageing is similar with (higher values) or without BOO. DO also induces an increased detrusor contractility.

LEVEL OF EVIDENCE

4.

[Quantification of bladder-outlet obstruction in males: standard method vc VBN method]

GOAL

To compare the merits of two methods, standard (Abrams-Griffiths number, Schafer's classification, etc.) and VBN, to study bladder-outlet obstruction in men with benign prostatic hyperplasia (BPH).

MATERIAL AND METHODS

The parameters deduced from both methods and from repeated pressure-flow studies were computed for a population of patients with BPH. Correlation coefficients between standard and VBN parameters were systematically evaluated. Test-retest reliability and inter-rater reliability of the VBN parameters were investigated.

RESULTS

The VBN obstruction parameter was linearly corelated to the A-G number (R = 0.992) and thus is related to the provisional ICS obstruction nomogram. A simple modification to the standard index projected isometric pressure (PIP) yields an mPIP parameter strongly correlated with the VBN detrusor contraction-strength parameter (R = 0.962). VBN analysis reveals minor phenomena such as premature fading of the detrusor contraction to be responsible for much of the void-to-void variability of pressure-flow studies. Consequently, the primary VBN obstruction and contraction-strength parameters exhibit better test-retest and inter-rater reliability than the standard parameters and are less sensitive to changes in testing circumstances (bladder volume, urethral catheter size and psychological factors).

CONCLUSION

With the standard approach to test bladder obstruction, two values: A-G and mPIP, derived from pressure-flow studies, best qualify the patient's voiding status. These parameters are simple to calculate but are sensitive to testing variations and minor phenomena. The VBN approach is more complicated, but its parameters for obstruction and detrusor contraction strength are less dependent on testing variations.

[Urodynamics and uterine fibroid. Is there a specific parameter?]

AIM OF STUDY

To search for a urodymamical parameter and/or a VBN parameter (deduced from a modelized analysis of uroflows) which could characterize the voiding dysfunctions due to a uterine fibroid.

POPULATION AND METHODS

Thirty women (31-69 years) with a uterine fibroid (exclusion criteria: neurological disease, diabetes mellitus, previous pelvic surgery, grade > I prolapse) underwent one urodynamic session which included the successive tests: free uroflow, urethral profilometry, cystometry and, if possible, a second free uroflow. Twenty-eight patients complained from stress urinary incontinence. Modelized analysis of the flow curves was performed in order to determine the value of two VBN parameters: urethral parameter g and recruitment ratio rr (which quantify the ratio of firing motor neurons during detrusor contraction).

RESULTS

The fibroid (known for 23 subjects) was detected during gynaecological examination in seven cases. No significant change of the value of one urodynamical parameter which could be linked to the uterine fibroid rather than the urinary disorder has been found. Some urethral constrictive obstruction exists for 18 patients (g = 0.40 +/- 0.15) but is not meaningful. In the whole population, an effective abdominal pressure is found in 78% of the analyzed micturitions.

CONCLUSION

Some urinary disorders result from the presence of a uterine fibroid; they are significantly improved by simple hysterectomy. If urodynamics does not have any specificity, concomitant physical examination allows to detect fibroids with only urinary symptomatology.

[Are age and urodynamic data correlated in women with stress urinary incontinence (SUI)?]

PURPOSE

Our aim was to evaluate the impact of age on lower urinary tract function in women by means of urodynamics and modelized analysis of the recorded free uroflow curves.

MATERIAL AND METHODS

One hundred and fifty three women (age range: [30-93 years]; 6 decades A to F) with only SUI complaint underwent a urodynamic evaluation which included initial free uroflow, urethral pressure profile, cystometry and final free uroflow at bladder functional capacity. Modelized analysis was performed using the VBN mathematical micturition model; from comparison between recorded and computerized theoretical flow curves this model allows to determine two characteristic parameters: one of urethral obstruction and one of detrusor efficiency.

RESULTS

No age-related changes were found in bladder capacity, peak flow rate in the first void and post residual volume. A significant increase of peak flow rate was noted in the second void for D and older. Bladder compliance decreased only from E. As usually described a decrease with age of the maximum urethral closure pressure occurred while the functional urethral length decreased only from E. A flat distribution of the VBN parameters was observed.

DISCUSSION-CONCLUSION

This study shows the absence of age-associated changes in both urodynamic data and VBN parameters in a population of women with SUI and without any other disease. These findings reinforce the idea that chronological age does not strongly correlate with the physiological status.

A mathematical micturition model to restore simple flow recordings in healthy and symptomatic individuals and enhance uroflow interpretation

We describe a model and report a new method to extract quantified data from the simple analysis of whole uroflow curves in healthy and symptomatic individuals. Recorded flow curves were compared with the curves theoretically predicted from a mathematical micturition model. This model was developed by relating each physiological event occurring during micturition to a set of mathematical equations. Due to improvements in speed of computer calculations, a very fast and adaptable mathematical micturition model became available. A total of 302 uroflow curves from 142 patients (61 men and 81 women) were studied. The control group consisted of seven men and 25 women; the symptomatic groups comprised 54 men and 56 women. The mathematical model was applied to analyze all the recorded curves. For patients with lower urinary tract symptoms, specific modelization parameters were introduced according to the clinical condition to be tested. Using two compulsory (patient sex and voided volume) and two optional parameters (clinical condition and urethral catheter size), our mathematical model was able to produce uroflow calculated curves similar to observed curves. In the control group, the calculated and recorded uroflow curves were found to superimpose with an impressive accuracy, i.e., a quadratic error <1%. Test-re-test studies gave the same determination of the specific parameters. In benign prostatic hyperplasia patients, the compressive effect on both prostatic urethra and bladder neck was separately identified. The same intra-individual values were found at 2-week intervals in the group with no treatment (P = no significance), whereas after 3 months of treatment with an alpha-blocker, a decrease in values was noted in responder patients (P < 0.001). In women with various degrees of cystocele, a constrictive effect was identified and found to be identical for successive flows during the same urodynamic testing. This large prospective study demonstrated the relevance of a sophisticated, heavily computerized micturition model, taking into account physiological voiding parameters, to the study of flow in healthy individuals and patients with benign prostatic hyperplasia or cystocele. Curve-fitting led to the determination of critical events during flow such as break point and plateau phase. Determination of these events may enhance uroflow interpretation by providing additional information on the detrusor function. Neurourol. Urodynam. 19:153-176, 2000.

The Academy of Health Information Professionals: a review of the first five years

The Medical Library Association (MLA) has provided its members with a credentialing program since 1949. This article reports on a five-year review of the current program, the Academy of Health Information Professionals. The review included an analysis of the financial basis of the academy and the use of three different survey instruments designed to gather input from MLA members and other opinion leaders. A final report to the MLA Board of Directors set forth eight recommendations based on questions and concerns identified during the review process.

Library services for people with disabilities: results of a survey

The Americans with Disabilities Act (ADA), enacted in 1990, has had a significant impact on the way many institutions, including libraries, do business. The Association of Research Libraries surveyed its members in 1991 to determine the effect of this legislation, and the author conducted a similar survey in 1995 to learn what progress academic health sciences libraries have made in serving the needs of people with disablities. A questionnaire was mailed to 131 members of the Association of Academic Health Sciences Library Directors. Nearly three-quarters of respondents reported elimination of physical barriers. The most common services provided are retrieval of materials from the stacks and photocopy assistance. Much less attention has been paid to the use of adaptive technology that allows disabled users to search a library's online catalog and databases; special technology is often provided by another unit on campus but there seems to be little coordination with library services Few libraries have assigned responsibility for disability services to a specific staff member and even fewer have done a formal assessment of the need for special services. The issues identified by the survey should challenge academic health sciences libraries to examine their status regarding compliance with ADA legislation.

Mathematical model of muscular fatigue. Part III. Classification of muscular fibres versus metabolism of exhaustion

In order to modelize muscular fatigue, use and depletion of energizing stores are incorporated in the previously elaborated model. The role of muscle glycogen is crucial in sustained muscular contractions. Two patterns of muscular exhaustion are described: one is related to glycogen depletion (S and FR fibres) and the other to an unphysiological drop in ATP concentrations (FF fibres). Thus, the muscle fibre recruitment can be related to its theoretical metabolism of exhaustion. The importance of the muscle lactate level is connected to the glucose entry into the muscle cell and the rigor mortis. Computations have been carried out on a computer DPS 7.

Mathematical model of muscular fatigue. II. Changes of metabolites level and of force during exercise in relation to a fatigability parameter

In order to study muscular fatigue, a mathematical model allowing the simulation of changes of metabolites level and of force during exercise in human muscle is built. It results from the association of two previous models and from the introduction of two parameters (pH and ATP concentration) influencing directly the muscular force and of the fatigability parameter (A) which characterizes the oxidative capacity of a given fibre. Simulations of physiological conditions of exercise and recovery allow one to bring out a classification of muscular fibres in terms of the fatigability parameter. In addition, the study of successive exercises underlines the lactate level role in force generation. Computations have been carried out on a computer DPS 7.

Mathematical model of muscular fatigue. I. Metabolite level changes during exercises of different intensities

To quantify muscular fatigue we study by a mathematical modelization the changes of the levels of ATP and various metabolites, and of the oxygen uptake with the intensity of a requested muscular exercise. The proposed model is consistent with the main phenomena experimentally observed during exercises; it allows also one to extrapolate these experimental results to any condition and to simulate exercise-complete and/or incomplete recovery cycles. The lactate kinetics allows one particularly to justify the empirical optimization of rest rhythms during exercises of long duration. Equations are solved using a 4th order Runge-Kutta method; computations are performed on an IRIS 80 CII computer.

Reassociation of histone H1 with nucleosomes

The role of histone H1 in nucleosome heterogeneity and structure has been studied using a reconstitution procedure. Histone H1 and non-histone proteins are removed selectively from enzymatically fragmented chromatin by Dowex 50W-X2 treatment. The resulting "stripped" chromatin then is reassociated with purified histone H1 using step gradient dialysis. Material reconstituted in this manner was examined by gel electrophoresis, protein cross-linking, and chromatin fingerprinting. The results demonstrate that the histone H1 molecule efficiently binds to nucleosomes with fidelity in an apparent noncooperative manner. Polynucleosomes possess two specific binding sites for histone H1 per histone octamer; the first binding site is of higher affinity than the second. The 160-base pair nuclease digestion barrier and nucleosome electrophoretic class (MIII)n are established upon binding the 1st histone H1 molecule. Upon binding the 2nd histone H1 molecule, polynucleosomes assume a highly compact conformation. The experimental approach introduced here should permit determining whether nucleosomes possess independent specific binding sites for other chromosomal proteins, and should allow reconstitution of the other electrophoretic forms of nucleosomes which we have described previously.

Histone molar ratios among different electrophoretic forms of mono- and dinucleosomes

The relative molar ratios of each of the histone classes and protein A24 have been determined in nuclei, chromatin, and different electrophoretic forms of mono- and dinucleosomes of cultured mouse cells. For this purpose, [3H]lysine- and [14C]arginine-labeled cells were used for sample preparations, and stoichiometries were estimated from protein radioactivity profiles and known amino acid compositions following sodium dodecyl sulfate (SDS)-gel electrophoresis. The results demonstrate that upper limits of one and two histone H1 molecules exist per mono- and dinucleosome, respectively. However, isolated nuclei contain less than one copy of histone H1 per nucleosome. In addition, among the chromatin subfractions studied, histones H3, H2B, and H4 are essentially equimolar, while histone H2A is less than equimolar by 19 +/- 9%. This latter finding offers direct support to the proposal of Goldknopf (Goldknopf, I. L., French, M. F., Musso, R., and Busch, H. (1977) Proc. Natl. Acad. Sci. U. S. A. 74, 5492-5495) that protein A24 replaces histone H2A in the octamer protein core of the nucleosome, since about 10% of the total histone H2A of cultured mouse cells is in the form of protein A24 and is present in nucleosomes. From the results of the present study, it is concluded that electrophoretic fractionation of mono- and dinucleosomes is not due to variable molar ratios or amounts of the four smaller histone classes, but depends on part on DNA length, the number of associated histone H1 molecules, and non-histone chromosomal proteins.