TABLE 4.
Accuracy of participant-interpreted influenza self-test based on number of symptoms, impact on activities, and time intervals
| Mean Ct value | TPb | FPb | FNb | TNb | Sensitivity (95% CI) |
Specificity (95% CI) |
|
|---|---|---|---|---|---|---|---|
| No. of symptoms | |||||||
| 0 to 3 | 30.1 | 3 | 0 | 10 | 107 | 23% (5 to 54) | 100% (97 to 100) |
| 4 to 7 | 28 | 15 | 11 | 55 | 349 | 21% (13 to 33) | 97% (95 to 98) |
| 8 to 12 | 26.4 | 46 | 5 | 70 | 287 | 40% (31 to 49) | 98% ( 96 to 99) |
| Impact on activities | |||||||
| Not at all | 30 | 1 | 0 | 6 | 76 | 14% (0 to 58) | 100% (95 to 100) |
| A little bit | 29.1 | 10 | 6 | 29 | 284 | 26% (13 to 42) | 98% (96 to 99) |
| Somewhat | 27.1 | 15 | 4 | 33 | 226 | 31% (19 to 46) | 98% (96 to 100) |
| Quite a bit | 26.8 | 20 | 6 | 41 | 111 | 33% (21 to 46) | 95% (89 to 98) |
| Very much | 25.8 | 18 | 0 | 26 | 46 | 41% (26 to 57) | 100% (92 to 100) |
| Trigger-test interval | |||||||
| 0 to 24 | 26.6 | 54 | 10 | 104 | 533 | 34% (27 to 42) | 98% (97 to 99) |
| 24 to 48 | 28.2 | 9 | 2 | 18 | 83 | 33% (17 to 54) | 98% (92 to 100) |
| 48 to 72 | 32.2 | 1 | 0 | 4 | 21 | 20% (1 to 72) | 100% (84 to 100) |
| 72 to 96 | 33.1 | 0 | 1 | 1 | 37 | 0% (0 to 97) | 97% (86 to 90) |
| Onset-test interval | |||||||
| 0 to 24a | n/a | 0 | 0 | 0 | 17 | NaN (00 to 00) | 100% (80 to 100) |
| 24 to 48 | 27.1 | 16 | 3 | 36 | 132 | 31% (19 to 45) | 98% (94 to 100) |
| 48 to 72 | 25.7 | 22 | 4 | 36 | 200 | 38% (26 to 52) | 98% (95 to 99) |
| 72 to 96 | 27.3 | 14 | 2 | 33 | 145 | 30% (17 to 45) | 99% (95 to 100) |
a
No influenza positive individuals by index test or reference test within 24 h of reported symptom onset.
b
TP, true positive; FP, false positive; FN, false negative; TN, true negative.