An Extended Laboratory Validation Study and Comparative Performance Evaluation of the Abbott ID NOW™ COVID-19 Assay in a Coastal California Tertiary Care Medical Center

Abstract

The Abbott ID NOW COVID-19 assay is a rapid molecular diagnostic test particularly designed for on-site, rapid turnaround point of care (POC) testing. The utilization of rapid diagnostic tests is integral to optimizing workflow within the hospital and/or procedural-based clinics. The capability to provide both rapid disposition and correct patient classification during this COVID-19 pandemic is critically important with broad infection control implications for both patients and healthcare staff. A tightly controlled, extended laboratory validation was performed at our medical center to determine the negative test agreement of the Abbott ID NOW compared with the BD MAX analyzer, a laboratory-based, two target, molecular analyzer with a sensitive cycle threshold (Ct) positive cutoff value of 42. There was strict adoption of the procedures listed in the Abbott ID NOW Instruction for Use (IFU)1 insert delineating preferred practices for optimal test performance. Under these conditions, our institution demonstrated a significant negative percent agreement with 116 out of 117 patients correlating, which equates to a 99.1% concordance similar to a recently reported correlation study2.

Acceptable performance of the Abbott ID NOW among symptomatic individuals with confirmed COVID-19

“…While there were instances in our study where the ID NOW was positive and the RT-PCR was negative, we believe these are true positives for several reasons. Participants recruited in our study were all recently diagnosed with COVID-19; none of the samples from the asymptomatic individuals at low risk of COVID-19 gave false positive results throughout the study; when retested in triplicate or on an alternative platform, 40 % of the discrepant RT-PCR samples had detectable SARS-CoV-2 RNA present; and no issues with false positive results have been identified by the ID NOW manufacturer or among previous publications within the literature [2–17]. We feel that the discrepancies between the ID NOW and RT-PCR are probably related to other factors, such as the variability that comes with collecting multiple specimens.…”

Extraction-free RT-LAMP to detect SARS-CoV-2 is less sensitive but highly specific compared to standard RT-PCR in 101 samples

“… Method Sample type 1 Cost Complexity Scalability Sensitivity Refs. Viral culture NP in VTM Expensive Complex Not scalable Culturable when Ct <24 [ 31 ] RT-PCR (central lab protocols) Extracted NP Expensive Complex Kits, tubes and tips Comparator [ 45 ] Cepheid GeneXpert NP in VTM Expensive Simple Platform and single-use cartridges 95-100% [ 11 , 21 ] Abbott ID NOW Direct NP Expensive Simple Platform and single-use cartridges 70-90% [ 45 , 46 ] Abbott Panbio Ag Direct NP Cheap Simple Single-use cartridges 75-85% [ 34 , 47 , 48 ] NEB RT-LAMP Extract-free NP Cheap Simple Kit, tubes and tips 75-95% [ 23 ] 1...…”

Sensitivity of ID NOW and RT–PCR for detection of SARS-CoV-2 in an ambulatory population

“…Authors also performed a limit-of-detection analysis and found an LOD for ID NOW of 20,000 copies/ml, with LOD for Xpert Xpress of 100 copies/ml, and 1000 copies/ml for GenMark ePlex. Comer (Comer and Fisk, 2020) This study sampled all COVID-19 symptomatic prospective hospital admissions with combined nasopharyngeal (NP) and oropharyngeal (OP) swabs in the ED with the Abbott ID NOW and tested them immediately in the emergency department, if negative, recollect expeditiously and test on a Becton Dickinson BD MAX. Retesting occurred within a few hours.…”