Table 5.
Discrepant Analysis: Discrepancies in the Results between the Evaluated Methods and Discrepancies in the Results between Specimens Analyzed with the Old and the New Version of Amplidiag Software
| Number of specimens | Reference standard result | Cobas SARS-CoV-2 test result |
LDT result |
Amplidiag COVID-19 test result |
Comments |
|---|---|---|---|---|---|
| (orf1ab CT/E gene CT) | (N gene CT) | (N gene CT/orf1ab CT) | |||
| 1 | Neg | Neg (no CT) | Neg (no CT) | Pos (no CT/40.8) | Incorrect interpretation of the amplification curve by Amplidiag Analyzer |
| 1 | Pos | Pos (33.7/34.9) | Neg (no CT) | Pos (no CT/38.1) | |
| 1 | Pos | Pos (32.3/33.3) | Pos (30.46) | Neg (no CT) | The specimen had gone through two freezing–thawing cycles when analyzed by Amplidiag and only one with cobas test and none with LDT |
| 9 | Neg | Pos (28.6–34.4/29.1–37.9) | Neg (no CT) | Neg (no CT) | All specimens positive by cobas only had a late CT value. Apart from one specimen, all had a CT value > 30. Two of the specimens gave a positive result when specimens were rerun with the new Amplidiag software. |
| Number of specimens | Amplidiag result with old software |
Amplidiag result with new software |
Comments |
|---|---|---|---|
| (N gene CT/orf1ab CT) | (N gene CT/orf1ab CT) | ||
| 1 | Pos (no CT/40.8) | Neg (no CT/no CT) | Incorrect interpretation of the amplification curve by the old Amplidiag software version |
| 4 | Pos (no CT-38.1-no CT/38.5–40.8) | Neg (no CT/27.8–30.5) | New Amplidiag software version interprets the result as negative even though there is amplification from orf1ab gene |
| 2 | Neg (no CT/no CT) | Pos (27.5–28.0/no CT-27.5) | Specimens positive by cobas test |
| 2 | Pos (no CT/38.0–39.6) | Neg (no CT/no CT) |
Note that 10 CT cycles must be added to the CT value obtained with the new version of the software to compare the values to the CT values obtained by the old version.
LDT, laboratory-developed test.