This study aim to validate the clinical performances of two newly developed isothermal nucleic acid amplification bioassays modules for EBOV and LASV. Two retrospective studies will be conducted using biobanked patient samples such as plasma samples and buccal swabs already collected by the Centre de Recherche en Virologie, Laboratoire des Fièvres Hémorragiques Virales de Guinée (CRV-LFHVG) as part of their surveillance and outbreak activities. The diagnostic sensitivity and specificity of the EBOV and LASV bioassays modules will be compared to the gold-standard reverse transcriptase polymerase chain reaction (RT-PCR) technologies used in the national reference lab.
The FORTIFIEDx \& DECIPHER projects aim to improve the diagnostic capacity for VHFs by developing two novel POC diagnostic tools capable of detecting EBOV and LASV. These tools are designed to enhance diagnostic sensitivity and specificity compared to existing rapid diagnostic solutions, thereby enabling faster and more accurate case detection. Improved diagnostic performance is expected to lead to better patient care and more effective outbreak control. Additionally, it aims to minimize healthcare worker's exposure to contaminated bodily fluids by supporting self-testing with healthcare worker assistance. To validate the clinical performance of both the FORTIFIEDx and DECIPHER bioassays modules, two retrospective studies will be conducted using biobanked plasma samples and/ or buccal swabs from patients previously tested for EBOV and LASV. These samples, collected by the CRV-LFHVG, include both test-positive and test-negative cases confirmed by gold-standard RT-PCR assays. These studies are crucial steps in the evaluation of the FORTIFIEDx \& DECIPHER diagnostic tools. Leveraging existing biobanked samples allows for the generation of clinically relevant performance data without the need for new patient recruitment. The primary objective is to estimate the sensitivity and specificity of the bioassay modules for LASV and EBOV compared to standard RT-PCR on biobanked patient samples. As a secondary objective, the investigators will evaluate other endpoints related to diagnostic accuracy and concordance (e.g. positive and negative predictive values) and the inverstigators will evaluate the user-friendliness (by the laboratory technician) of the bioassay modules.
Study Type
OBSERVATIONAL
Enrollment
150
FORTIFIEDx bioassay, using recombinase polymerase amplification for a qualitative readout and DECIPHER bioassay, using recombinase polymerase amplification for a quantitative readout
Assess sensitivity and specificity of the FORTIFIEDx and DECIPHER bioassays for EBOV and LASV
The FORTIFIED assay gives qualitative results. The DECIPHER assay gives quantitative results for EBOV and LASV, which will be classified as positive or negative. It is assumed that a higher value indicates a higher viral load. The threshold for each pathogen will be determined as follows: (1) the maximum threshold that achieves ≥80% sensitivity, (2) the minimum threshold that achieves ≥80% specificity, (3) the threshold that maximizes Youden's index and (4) the threshold that minimizes the Euclidean index. Note that approach (1) and (2) will give an unbiased estimate of sensitivity and specificity at these pre-specified thresholds, while approach (3) and (4) is expected to overestimate sensitivity and specificity. Sensitivity and specificity (together with their 95% Wilson CI) will be calculated using the observed number of true and false positives and negatives. Positive and negative predictive value will be estimated using the calculated sensitivity and specificity.
Time frame: Up to 1 year after the intervention
Evaluate the usability of the bioassays by laboratory technicians - quantitative feedback
Responses from the standardized questionnaire completed by laboratory technicians will be analysed using descriptive statistics. Quantitative usability metrics (such as ease of use scores, time requirements, and satisfaction ratings) will be summarized using (cumulative) counts and percentages or using medians, quartiles and ranges as appropriate.
Time frame: Up to 1 year after the intervention
Evaluate the usability of the bioassay by laboratory technicians - qualitative feedback
Responses from the standardized questionnaire completed by laboratory technicians will be analysed using descriptive statistics. Qualitative feedback regarding workflow integration, clarity of instructions, and implementation challenges will be categorized and analysed thematically to identify common patterns and areas for improvement in the bioassay system design and user interface.
Time frame: Up to 1 year after the intervention
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