TABLE 3.
Accuracy of influenza self-test compared to laboratory reference test
| Interpreter | Mean Ct value | TPd | FPd | FNd | TNd | Sensitivity (95% CI) |
Specificity (95% CI) |
Positive likelihood ratio (95% CI) | Negative likelihood ratio (95% CI) |
|---|---|---|---|---|---|---|---|---|---|
| Participanta,b | 27.2 | 64 | 16 | 135 | 743 | 32% (26 to 39) |
98% (97 to 99) |
15.3 (9.0 to 25.8) |
0.69 (0.63 to 0.76) |
| Expert | 27.2 | 57 | 3 | 144 | 762 | 28% (22 to 35) |
100% (99 to 100) |
72.31 (22.9 to 230) |
0.72 (0.66 to 0.78) |
| Consensusc | 27.3 | 52 | 1 | 131 | 741 | 28% (22 to 36) |
100% (99 to 100) |
210.8 (29.3 to 1500) |
0.72 (0.65 to 0.79) |
| Participant interpretation of flu Ab | 27.0 | 40 | 11 | 103 | 804 | 28% (21 to 36) |
99% (98 to 99) |
20.7 (10.9 to 39.4) |
0.74 (0.67 to 0.81) |
| Participant interpretation of flu Bb | 27.8 | 18 | 11 | 38 | 891 | 32% (20 to 46) |
99% (98 to 99) |
26.9 (13.4 to 54.1) |
0.69 (0.57 to 0.82) |
| Participant interpretation,a,b 20192020 flu vaccine = “Yes” |
26.4 | 30 | 12 | 69 | 380 | 30% (21 to 40) |
97% (95 to 98) |
9.90 (5.26, 18.63) |
0.72 (0.63 to 0.82) |
| Participant interpretation,a,b 20192020 flu vaccine = “No” |
28 | 34 | 4 | 66 | 363 | 34% (25 to 44) |
99% (97 to 100) |
31.2 (11.3 to 85.8) |
0.67 (0.58 to 0.77) |
| Expert interpretation,a 20192020 flu vaccine = “Yes” |
26.4 | 30 | 2 | 71 | 392 | 30% (21 to 40) |
99% (98 to 100) |
58.5 (14.2 to 240.8) |
0.71 (0.62 to 0.80) |
| Expert interpretation,a 20192020 flu vaccine = “No” |
28 | 27 | 1 | 73 | 370 | 27% (19 to 37) |
100% (99 to 100) |
100.2 (13.8 to 728.2) |
0.73 (0.65 to 0.82) |
a
Ten tests were designated invalid by participants and by the expert and thus excluded from performance.
b
Participants interpreted eight tests as having lines both above and below the control line and these results were excluded from performance analysis.
c
Includes only RDTs for which the participant and expert agreed on the result.
d
TP, true positive; FP, false positive; FN, false negative; TN, true negative.