Many studies reported good performance of nasopharyngeal swab-based antigen tests for detecting SARS-CoV-2-positive individuals; however, studies independently evaluating the quality of antigen tests utilizing anterior nasal swabs or saliva swabs are still rare, although such tests are widely used for mass testing. In our study, sensitivities, specificities and predictive values of seven antigen tests for detection of SARS-CoV-2 (one using nasopharyngeal swabs, two using anterior nasal swabs and four using saliva) were evaluated. In a setting of a high-capacity testing center, nasopharyngeal swabs for quantitative PCR (qPCR) were taken and, at the same time, antigen testing was performed in accordance with manufacturers' instructions for the respective tests. In samples where qPCR and antigen tests yielded different results, virus culture was performed to evaluate the presence of the viable virus. Sensitivities and specificities of individual tests were calculated using both qPCR and qPCR corrected for viability as the reference. In addition, calculations were also performed for data categorized according to the cycle threshold and symptomatic status. The test using nasopharyngeal swabs yielded the best results (sensitivity of 80.6% relative to PCR and 91.2% when corrected for viability) while none of the remaining tests (anterior nasal swab or saliva-based tests) came even close to the WHO criteria for overall sensitivity. Hence, we advise caution when using antigen tests with alternative sampling methods without independent validation.
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Antigen testing for SARS-CoV-2 is considered to be less sensitive than the standard reference method - real-time PCR (RT-PCR). It has been suggested that many patients with positive RT-PCR 'missed' by antigen testing might be non-infectious. METHODS: In a real-world high-throughput setting for asymptomatic or mildly symptomatic patients, 494 patients were tested using RT-PCR as well as a single lateral flow antigen test (Ecotest, AssureTech, China). Where the results differed, virus viability was evaluated by cell culture. The test parameters were calculated with RT-PCR and RT-PCR adjusted on viability as reference standards. RESULTS: The overall sensitivity of the used antigen test related to the RT-PCR only was 76.2%, specificity was 97.3%. However, 36 out of 39 patients 'missed' by the antigen test contained no viable virus. After adjusting on that, the sensitivity grew to 97.7% and, more importantly for disease control purposes, the negative predictive value reached 99.2%. CONCLUSIONS: We propose that viability testing should be always performed when evaluating a new antigen test. A well-chosen and validated antigen test provides excellent results in identifying patients who are shedding viable virus (although some caveats still remain) in the real-world high-throughput setting of asymptomatic or mildly symptomatic individuals.
- MeSH
- antigeny virové MeSH
- COVID-19 * MeSH
- lidé MeSH
- SARS-CoV-2 MeSH
- senzitivita a specificita MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Čína MeSH
Antigen testing for SARS-CoV-2 (AGT) is generally considered inferior to RT-PCR testing in terms of sensitivity. However, little is known about the infectiousness of RT-PCR positive patients who pass undetected by AGT. In a screening setting for mildly symptomatic or asymptomatic patients with high COVID-19 prevalence (30-40%), 1141 patients were tested using one of five AGTs and RT-PCR. Where the results differed, virus viability in the samples was tested on cell culture (CV-1 cells). The test battery included AGTs by JOYSBIO, Assure Tech, SD Biosensor, VivaChek Biotech and NDFOS. Sensitivities of the ATGs compared to RT-PCR ranged from 42% to 76%. The best test yielded a 76% sensitivity, 97% specificity, 92% positive, and 89% negative predictive values, respectively. However, in the best performing ATG tests, almost 90% of samples with "false negative" AGT results contained no viable virus. Corrected on the virus viability, sensitivities grew to 81-97% and, with one exception, the tests yielded high specificities >96%. Performance characteristics of the best test after adjustment were 96% sensitivity, 97% specificity, 92% positive, and 99% negative predictive values (high prevalence population). We, therefore, believe that virus viability should be considered when assessing the AGT performance. Also, our results indicate that a well-performing antigen test could in a high-prevalence setting serve as an excellent tool for identifying patients shedding viable virus. We also propose that the high proportion of RT-PCR-positive samples containing no viable virus in the group of "false negatives" of the antigen test should be further investigated with the aim of possibly preventing needless isolation of such patients.
- MeSH
- antigeny virové analýza MeSH
- COVID-19 diagnóza imunologie MeSH
- dospělí MeSH
- falešně negativní reakce MeSH
- lidé středního věku MeSH
- lidé MeSH
- mikrobiální viabilita * MeSH
- plošný screening MeSH
- SARS-CoV-2 imunologie MeSH
- senzitivita a specificita MeSH
- sérologické testy metody MeSH
- testování na COVID-19 průkazem nukleové kyseliny MeSH
- testování na COVID-19 metody MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Ankle brachial index (ABI) is the principal screening method for peripheral arterial disease (PAD). In this study, we compare various types of Doppler-derived and oscillometric ABIs with results obtained through duplex ultrasonography. METHODS: 62 patients were enrolled in the study. For each limb, blood pressures for both ankle arteries and the arm were measured using Doppler and an automated oscillometric device. Duplex ultrasound was performed for all limbs and occlusions >50% were considered PAD-positive. ABI was calculated using both higher (HABP) and lower (LABP) arterial blood pressure on the individual limbs and the ability to predict duplex-detected stenoses was evaluated. RESULTS: LABP calculation provided results superior to the guideline-recommended HABP. Considering patients with ABI >1.4 or measurement failure as PAD-positive further enhanced the test parameters. The higher ABI cut-off of 1.0 resulted in somewhat better sensitivities (max 92%) and negative predictive values (max 87%) at the expense of a substantial increase in the number of false positives. Oscillometric method yielded poor sensitivities but very good specificities (max 94%) and positive predictive values (max 90%). CONCLUSIONS: Doppler-based LABP provides better results than the guideline-recommended HABP in diabetic patients, nevertheless even this method is not perfect. Increasing the cut-off value to 1.0 in these patients does not bring a substantial improvement of the test performance. Patients with high ABI should be automatically considered PAD-positive and referred for further investigation using imaging techniques.
- MeSH
- arteriální okluzní nemoci diagnóza patofyziologie MeSH
- diabetické angiopatie diagnóza patofyziologie MeSH
- krevní tlak fyziologie MeSH
- lidé MeSH
- onemocnění periferních arterií diagnóza patofyziologie MeSH
- senioři MeSH
- senzitivita a specificita MeSH
- tlakový index kotník-paže metody MeSH
- ultrasonografie dopplerovská metody MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Aterosklerotické postižení karotid je stále poměrně kontroverzní téma, především pokud se týká intervenční léčby, ale i doporučení k provedení diagnostického ultrazvukového vyšetření. V naší studii jsme u rizikové skupiny diabetických pacientů navštěvujících kardiologickou ambulanci prováděli vyšetření karotid duplexním ultrazvukem a výskyt jsme porovnávali s výskytem ischemické choroby dolních končetin (ICHDK) a indexem kotník-paže (ankle-brachial index ABI) získaným s použitím nižší hodnoty systolického krevního tlaku na úrovni kotníku. Celkem 87,1 % pacientů mělo aterosklerotické postižení karotid, z toho 27,4 % stenózu karotid vyšší než 50 % a u 9,7 % pacientů byla detekována dokonce významná stenóza (přes 70 % lumen). U věkové skupiny pacientů nad 60 let byly tyto počty ještě vyšší. Detekovali jsme také vztah mezi ICHDK a významnou stenózou karotid, stejně jako mezi hodnotou ABI vypočtenou z nižšího z kotníkových tlaků a významnou stenózou karotid, kdy žádný z pacientů bez ICHDK a žádný pacient s normální hodnotou ABI neměl významnou stenózu karotid. Domníváme se tedy, že u diabetických pacientů navštěvujících kardiologické ambulance je vhodné vždy provést měření ABI dopplerometrickou metodou, které může sloužit jako screeningový nástroj nejen pro určování ICHDK, ale zároveň v případě abnormální hodnoty ABI k indikaci pro provedení duplexního vyšetření karotid.
Asymptomatic carotid atherosclerosis remains a relatively controversial topic with respect to both interventional therapy and recommendations for the use of diagnostic ultrasound. In our study, a group of high risk diabetic patients attending a cardiovascular clinic was examined using duplex ultrasound for carotid atherosclerosis and the results were compared with lower extremity arterial disease (LEAD) and the ankle-brachial index (ABI) obtained using the lower of ankle pressures. Carotid atherosclerosis was detected in 87.1% of patients, 27.4% of which had a stenosis of more than 50%, and significant stenosis (i.e., greater than 70%) was detected in 9.7% of patients. These numbers were even higher in the group of patients over 60 years of age. We also revealed a strong relationship between LEAD and significant carotid stenosis as well as between the ABI value, calculated using the lower arterial pressure, and significant carotid stenosis. No patient with normal ABI and no patient without LEAD had significant carotid stenosis. Hence, we conclude that it is beneficial to perform ABI measurement using Doppler ultrasound method and lower arterial pressure at the ankle level that can also serve, as well as the LEAD screening, as a useful tool for determining whether or not a duplex examination of carotids should be performed in the particular patient.
- Klíčová slova
- index kotník paže (ABI), ischemická choroba dolních končetin,
- MeSH
- arteriae carotides * diagnostické zobrazování patologie MeSH
- ateroskleróza * diagnostické zobrazování MeSH
- dolní končetina diagnostické zobrazování krevní zásobení patologie MeSH
- duplexní dopplerovská ultrasonografie metody MeSH
- ischemie diagnóza MeSH
- klinická studie jako téma MeSH
- komplikace diabetu MeSH
- lidé MeSH
- žilní insuficience * diagnóza MeSH
- Check Tag
- lidé MeSH
OBJECTIVES: In diabetic patients, there is a discrepancy in guidelines for ankle-brachial index (ABI) screening for peripheral arterial disease (PAD). While diabetes organizations suggest the value of upper limit of normal ABI to be 1.3, cardiologists recommend 1.4. Also, guidelines recommend using the higher value of ankle pres-sure (HAP) but multiple recent studies propose the opposite (LAP). METHODS: In this prospective study, we performed ABI measurements in 62 diabetic patients. Results were calculated by comparing higher and lower values of ankle pressure to those of duplex ultrasound (stenosis ≥ 50 % was considered PAD). Special attention was paid to patients with high and non-measurable ABI.RESULTS: LAP ABI appears to be a preferable method for PAD screening in diabetics. The upper cut-off value of 1.4 yielded better results with sensitivity of 93 % and negative predictive value of 91 %. No limbs with ABI between 1.3 and 1.4 with signifi cant stenosis were found. However, using HAP for the upper cut-off captured additional PAD patients. PAD was abundant among patients with high or non-measurable ABI.CONCLUSIONS: LAP should be used for assessing low ABI (cut-off 0.9) while HAP for detecting the abnormally high ABI. The preferable high ABI cut-off is 1.4. Condition with abnormally high or non-measurable ABI should be considered as PAD (Tab. 3, Ref. 22). Text in PDF www.elis.sk.KEY WORDS: ankle-brachial index, diabetes, peripheral arterial disease, lower extremity arterial disease, cut-off.
