Table 4.
Samples With Discordant Results or Immunosuppressiona
| DiaSorin | EUROIMMUN | Roche | Siemens | |||||
|---|---|---|---|---|---|---|---|---|
| Sample Type | Arbitrary Units (15.00)b | Ratio (0.80-1.10)b | Index (1.00)b | Index (1.00)b | Age, y | Sex | Days After Symptom Onset | Other |
| Negatives | ||||||||
| Prepandemic | <3.80 | 1.68 | 0.09 | <0.05 | NA | NA | NA | |
| Prepandemic | 98.2 | 0.41 | 0.10 | <0.05 | NA | NA | NA | |
| Prepandemic | 36.7 | 0.96 | 0.08 | <0.05 | NA | NA | NA | |
| Prepandemic | 16.6 | 2.49 | 0.09 | <0.05 | NA | NA | NA | |
| Prepandemic | 10.9 | 1.55 | 0.10 | <0.05 | 56 | M | NA | |
| Prepandemic | 4.79 | 1.07 | 0.09 | <0.05 | 30 | F | NA | Also positive for rubella IgG |
| Prepandemic | 8.60 | 4.29 | 0.10 | <0.05 | 53 | M | NA | Neurofibromatosis type 1 and adrenal adenoma |
| Cross-reactive | 11.5 | 3.24 | 0.13 | <0.05 | 11 | F | NA | NL63 seasonal coronavirus |
| Cross-reactive | 15.5 | 1.07 | 0.09 | <0.05 | 22 | F | NA | Hepatitis B |
| Cross-reactive | 9.25 | 0.91 | 0.08 | <0.05 | 36 | F | NA | ANA speckled at 1:640 |
| RT-PCR negative | <3.80 | 1.81 | 0.08 | <0.05 | 16 | M | NA | No symptoms, preprocedure test, and Noonan syndrome |
| No RT-PCR test | 37.9 | 0.29 | 0.06 | 0.08 | 17 | M | 39 | Foot rash of concern for possible post–COVID-19 sequelae |
| RT-PCR negativec | 16.7 | 0.36 | 0.09 | <0.05 | 49 | F | 4 | Eosinophilic esophagitis, hypertension, liver mass |
| RT-PCR negative | <3.80 | 0.95 | 0.07 | 0.11 | 28 | F | 35 | |
| RT-PCR negatived | 5.07 | 2.38 | 0.07 | 0.11 | 60 | F | 0 | Pernicious anemia |
| RT-PCR negative | <3.80 | 1.01 | 0.07 | 0.11 | 49 | F | 34 | Gilbert syndrome |
| RT-PCR negative | <3.80 | 0.89 | 0.06 | <0.05 | 51 | M | 19 | |
| RT-PCR negative | 8.20 | 0.99 | 0.06 | 0.15 | 37 | M | 16 | |
| RT-PCR negative | 4.01 | 1.05 | 0.06 | 0.15 | 33 | F | 15 | |
| Positives | ||||||||
| RT-PCR positive | 9.71 | 1.02 | 9.15 | 1.01 | 37 | F | 32 | |
| RT-PCR positive | 9.42 | 1.05 | 30.4 | 2.53 | 27 | F | 59 | |
| RT-PCR positive | 38.4 | 0.43 | 4.83 | 0.29 | 50 | F | 22 | |
| Immunosuppression | ||||||||
| RT-PCR positive | 41 | 5.83 | 25.8 | 5.15 | 28 | F | 44 | Systemic lupus erythematosus on hydroxychloroquine |
| RT-PCR positive | 268 | 13.06 | 58.5 | >10 | 63 | F | 48 | Rheumatoid arthritis on hydroxychloroquine and tofacitinib (tofacitinib paused during symptoms) |
| RT-PCR positive | 12.1 | 1.57 | 4.88 | 2.60 | 59 | F | 41 | Unclear rheumatologic condition on hydroxychloroquine |
| RT-PCR positive | 7.29 | 1.70 | 9.71 | >10 | 60 | M | 11 | Lung transplant on tacrolimus |
| RT-PCR positive | 24.0 | 0.83 | 15.5 | 1.48 | 59 | M | 14 | Kidney transplant on mycophenolate and tacrolimus |
| 90.5 | 8.11 | 43.2 | >10 | 19 |
ANA, anti–nuclear antibody by immunofluorescence; COVID-19, coronavirus disease 2019; IgG, immunoglobulin G; RT-PCR, reverse transcription polymerase chain reaction.
aDiscordant results are classified as nonconforming with expected results and/or other assays. Bold type indicates discordance, and italicized type indicates indeterminate results.
bThreshold for positivity (and indeterminate range for EUROIMMUN).
cRepeat testing by DiaSorin was 15.5 AU/mL. Testing 15 days later by EUROIMMUN was negative with ratio of 0.38.
dTwenty days later tested by DiaSorin with negative results, <3.8 AU/mL.