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Multisite Clinical Validation of Isothermal Amplification-Based SARS-CoV-2 Detection Assays Using Different Sampling
Kanan T Desai1, Karla Alfaro2, Laura Mendoza3
1Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, Maryland, USA.
Microbiology Spectrum
|October 20, 2021
Summary
The Atila iAMP COVID-19 test showed good sensitivity and specificity for detecting SARS-CoV-2, especially with midturbinate sampling in symptomatic patients. Performance varied by site, emphasizing the need for local validation of these rapid tests.
Area of Science:
- Clinical diagnostics
- Infectious disease detection
- Molecular assays
Background:
- Isothermal amplification tests offer rapid, low-cost alternatives to RT-PCR for SARS-CoV-2 detection.
- Clinical validation of these assays is crucial, especially under emergency use authorizations.
- Understanding performance variations across different sampling sites and patient groups is essential.
Purpose of the Study:
- To compare the clinical performance of two isothermal amplification-based SARS-CoV-2 tests (Atila iAMP and OptiGene RT-LAMP) against RT-PCR.
- To evaluate the impact of different sampling strategies on test sensitivity and specificity.
- To assess the utility of these rapid tests in diverse clinical settings.
Main Methods:
- A multicenter study involving 1,378 participants compared Atila iAMP and OptiGene RT-LAMP tests with RT-PCR assays.
- Various sampling strategies were employed, including nasopharyngeal, midturbinate, anterior nares, and saliva.
- Performance metrics (sensitivity, specificity) were analyzed based on patient symptoms, viral load, and sampling site.
Main Results:
- The Atila iAMP test demonstrated overall sensitivity of 76.2% and specificity of 94.9% versus RT-PCR, improving to 88.8% and 89.5% after excluding an outlier site.
- Sensitivity varied significantly by sampling site, with midturbinate yielding the highest sensitivity (88.2%).
- The OptiGene RT-LAMP test showed lower sensitivity (25.5%) but high specificity (100%).
- Higher sensitivity was observed in symptomatic patients and those with higher viral loads (Ct ≤ 25).
Conclusions:
- The Atila iAMP test, particularly with midturbinate sampling, is a promising rapid, low-cost option for SARS-CoV-2 detection, especially in symptomatic individuals with high viral loads.
- Site-specific validation is critical for ensuring reliable performance of isothermal amplification tests.
- These assays can facilitate safer clinical encounters and support public health efforts, especially in resource-limited settings.
