2.1 Study design
We here report data from an investigator-initiated, single-center, prospective registry study to evaluate Vivalytic™SARS-CoV-2 Multiplex POC (Bosch) COVID-19 test in clinical practice and to evaluate CT value at admission for risk stratification in hospitalized patients conducted at the Severinenklösterchen Hospital – University of Cologne.
The protocol of this study conforms to the ethical guidelines of the 1975 Declaration of Helsinki and was approved by the institutional ethical committee of the Ärztekammer Nordrhein (20211001).
2.2. Study population
All-comers admitted to the hospital over 18 years were eligible for inclusion.
The decision to perform a PCR-test for SARS-CoV-2 was made independently of study inclusion by the treating physician and patients were asked to participate before the test results were available.
Written informed consent was obtained from all patients prior to study inclusion.
Patients with a positive PCR-test for SARS-CoV-2 were finally allocated to the “positive” group, patients with a negative PCR-test for SARS-CoV-2 to the control group (Figure 1). Every patient was then tested 2 additional times using Vivalytic SARS-CoV-2 Test (Bosch), and SARS-CoV-2 Rapid Antigen Test (Rosche) respectively. All nasopharyngeal swabs were taken from nurses or trained personnel.
2.3. Study plan
Patient admitted to hospital between January and May 2021 were randomly asked to participate in the study. If patients had agreed to participate, overall characteristics such as sex, age and medical history were recorded.
To characterize the severity of the course of disease in COVID-19 patients were divided according to the length of stay (LOS) in: patients hospitalized for longer or shorter then 10 days .
All clinical data gathered during this period was obtained from the electronic patient file. During follow-up no interventions were applied for the purpose of this study and all therapeutic and diagnostic procedures were applied as part of standard care at the discretion of the treating physicians. Finally, participants were contacted by phone and asked about the course of disease using a standardized questionnaire after 3 month. Herein, the patients were asked to rank their current physical fitness on a scale from 0–100% in relation to the COVID-19 disease.
2.4 Measurements
SARS-CoV-2 testing using Allplex™ 2019-nCOV Assay (Seegene, Seoul, Korea: polymerase chain reaction assay (PCR) targeting envelope protein- (E-), RNA-dependent RNA polymerase- (RdRP-), and N- genes) was performed by an extern laboratory with Applied Biosystems™ 7500 Real-Time PCR System according to the manufacture guidelines.
For analysis with Bosch Vivalytic SARS-CoV-2 assay (Bosch Healthcare Solutions GmbH, Waiblingen, Germany) using the Vivalytic SARS-CoV-2 analyzer samples were collected in a guanidine thiocyanate-based medium eNAT® (COPAN Diagnostics Inc.; Murrieta, USA), stabilizing the viral RNA and completely inactivating the microbial viability. Vivalytic SARS-CoV-2 analyzer is a portable device and works fully automatically.
Roche SARS-CoV-2 Rapid Antigen Test is an immunochromatographic assay for qualitative detection of SARS-CoV-2 infection in nasopharyngeal swabs. The presence of viral antigens in sufficient concentration enables binding to specific mouse monoclonal anti-SARS-CoV-2 antibodies, which is then reflected by the appearance of a visual indication after clinical specimen is collected and then deposited in a pre-filled extraction buffer container with the solution being put on the test sample according to manufacture guidelines.
Inter-assay variability was performed conducting repetitive tests on four samples throughout three days. Intra-assay variability was performed conducting four consecutive assays in one run. Both times we were using inactivated whole pathogen sample: AMPLIRUN® TOTAL SARS-CoV-2 RNA Control (Vircell SA, Granada, Spain).
2.5. Statistic
Continuous patient data were compared using a Mann–Whitney U-test or unpaired T-test. Categorical differences between patient groups were compared using Fishers exact test. Continuous variables are presented as mean ± standard deviation (SD) if found to follow a Gaussian distribution according to the D'Agosstino-Pearson omnibus normality test or as median ± lower and upper quartiles if found to follow a non-Gaussian distribution. Categorical patient characteristics are presented as percentages. Spearman nonparametric correlation was used to evaluate the measures the degree to which LOS and CT value at admission move in relation to each other.
Descriptive analyses were performed using Graph Pad Prism Version 9.0 (Prism 9 for Mac OS X; GraphPad Software. Inc.. La Jolla. CA).