TABLE 3.
Performance of BinaxNOW compared to RT‐PCR (N = 1530 paired a tests from 1207 participants unless stated otherwise).
| Positive likelihood ratio (95% CI) | Negative likelihood ratio (95% CI) | Correctly classified proportion (95% CI) | Apparent positivity (95% CI) | True positivity (95% CI) | Number needed to diagnose (95% CI) | AUC‐ROC | |
|---|---|---|---|---|---|---|---|
| Overall | 68.89 (40.07, 118.41) | 0.16 (0.13, 0.20) | 0.943 (0.930, 0.954) | 0.264 (0.242, 0.287) | 0.304 (0.281, 0.328) | 1.2 (1.2, 1.3) | 0.914 |
| Days postonset b | |||||||
| 0 | Inf | 0.25 (0.12, 0.53) | 0.933 (0.851, 0.978) | 0.200 (0.116, 0.308) | 0.267 (0.171, 0.381) | 1.3 (1.1, 2.3) | 0.875 |
| 1–3 | 104.43 (33.81, 322.51) | 0.08 (0.04, 0.14) | 0.971 (0.952, 0.984) | 0.275 (0.236, 0.317) | 0.292 (0.251, 0.335) | 1.1 (1.0, 1.2) | 0.956 |
| 4–6 | 48.25 (18.27, 127.44) | 0.06 (0.03, 0.11) | 0.964 (0.939, 0.981) | 0.415 (0.364, 0.468) | 0.429 (0.377, 0.482) | 1.1 (1.0, 1.2) | 0.961 |
| ≥ 7 | 36.76 (11.91, 113.43) | 0.30 (0.23, 0.40) | 0.860 (0.813, 0.898) | 0.317 (0.262, 0.375) | 0.435 (0.376, 0.496) | 1.5 (1.3, 1.8) | 0.842 |
| Symptomatology c | |||||||
| Asymptomatic | 57.18 (18.29, 178.78) | 0.33 (0.23, 0.48) | 0.932 (0.898, 0.958) | 0.129 (0.094, 0.172) | 0.177 (0.137, 0.225) | 1.5 (1.3, 2.0) | 0.830 |
| ≥ 1 symptom | 69.65 (37.58, 129.11) | 0.14 (0.11, 0.18) | 0.946 (0.931, 0.958) | 0.299 (0.273, 0.325) | 0.336 (0.310, 0.364) | 1.2 (1.1, 1.2) | 0.925 |
| 1–3 symptoms | 54.39 (28.41, 104.15) | 0.14 (0.10, 0.18) | 0.943 (0.925, 0.957) | 0.315 (0.285, 0.347) | 0.352 (0.320, 0.385) | 1.2 (1.1, 1.3) | 0.925 |
| 4–6 symptoms | Inf | 0.25 (0.14, 0.46) | 0.935 (0.877, 0.972) | 0.194 (0.128, 0.274) | 0.258 (0.184, 0.344) | 1.3 (1.1, 1.9) | 0.875 |
| 7–9 symptoms | Inf | 0.13 (0.05, 0.37) | 0.971 (0.917, 0.994) | 0.194 (0.123, 0.284) | 0.223 (0.147, 0.316) | 1.2 (1.0, 1.6) | 0.935 |
| ≥ 10 symptoms | 64.04 (9.13, 449.18) | 0.09 (0.03, 0.22) | 0.957 (0.903, 0.986) | 0.376 (0.288, 0.470) | 0.402 (0.312, 0.496) | 1.1 (1.0, 1.4) | 0.950 |
| Collection strategy | |||||||
| Self, SEDSS | Inf | 0.15 (0.08, 0.28) | 0.940 (0.886, 0.974) | 0.343 (0.263, 0.430) | 0.403 (0.319, 0.491) | 1.2 (1.1, 1.5) | 0.926 |
| Staff, SEDSS | Inf | 0.21 (0.10, 0.42) | 0.968 (0.932, 0.988) | 0.122 (0.079, 0.178) | 0.154 (0.106, 0.214) | 1.3 (1.1, 1.7) | 0.897 |
| Self + Staff, SEDSS | Inf | 0.17 (0.10, 0.27) | 0.957 (0.928, 0.976) | 0.214 (0.171, 0.263) | 0.258 (0.211, 0.309) | 1.2 (1.1, 1.4) | 0.916 |
| Staff, COPA | 53.56 (31.18, 92.00) | 0.16 (0.13, 0.20) | 0.940 (0.925, 0.952) | 0.277 (0.252, 0.303) | 0.316 (0.290, 0.343) | 1.2 (1.2, 1.3) | 0.914 |
| Staff, SEDSS + COPA | 63.60 (37.00, 109.32) | 0.16 (0.13, 0.20) | 0.943 (0.930, 0.955) | 0.256 (0.234, 0.280) | 0.294 (0.271, 0.319) | 1.2 (1.2, 1.3) | 0.913 |
| Repeated tests d | |||||||
| Initial test | 24.08 (7.94, 73.03) | 0.04 (0.01, 0.10) | 0.962 (0.923, 0.985) | 0.587 (0.512, 0.659) | 0.592 (0.518, 0.664) | 1.1 (1.0, 1.3) | 0.961 |
| Repeated test 7–14 days after initial test | 20.48 (6.50, 64.53) | 0.52 (0.40, 0.67) | 0.821 (0.757, 0.873) | 0.174 (0.122, 0.237) | 0.321 (0.254, 0.393) | 2.1 (1.6, 3.4) | 0.734 |
| Number of vaccine doses e | |||||||
| Unvaccinated | Inf | 0.18 (0.12, 0.26) | 0.958 (0.936, 0.974) | 0.199 (0.165, 0.237) | 0.241 (0.204, 0.281) | 1.2 (1.1, 1.4) | 0.913 |
| 1 dose | 26.44 (3.72, 188.16) | 0.23 (0.07, 0.78) | 0.930 (0.809, 0.985) | 0.186 (0.084, 0.334) | 0.209 (0.100, 0.360) | 1.3 (1.0, 4.1) | 0.874 |
| 2 doses | 125.81 (31.52, 502.14) | 0.19 (0.14, 0.28) | 0.940 (0.914, 0.961) | 0.234 (0.195, 0.277) | 0.284 (0.242, 0.329) | 1.2 (1.1, 1.4) | 0.900 |
| 3 doses | 22.94 (11.60, 45.37) | 0.13 (0.08, 0.19) | 0.925 (0.893, 0.950) | 0.408 (0.357, 0.459) | 0.440 (0.389, 0.492) | 1.2 (1.1, 1.3) | 0.920 |
| 4 doses | 7.00 (1.14, 42.97) | 0.00 (0.00, 0.00) | 0.889 (0.518, 0.997) | 0.333 (0.075, 0.701) | 0.222 (0.028, 0.600) | 1.2 (−2.4, 1.0) | 0.929 |
| Predominant SARS‐CoV‐2 variant | |||||||
| Pre‐Delta | Inf | 0.20 (0.14, 0.30) | 0.958 (0.936, 0.974) | 0.167 (0.135, 0.203) | 0.209 (0.173, 0.248) | 1.2 (1.1, 1.4) | 0.900 |
| Delta | Inf | 0.30 (0.12, 0.77) | 0.982 (0.948, 0.996) | 0.042 (0.017, 0.085) | 0.060 (0.029, 0.108) | 1.4 (1.1, 3.1) | 0.850 |
| Omicron | 34.91 (20.37, 59.82) | 0.15 (0.11, 0.19) | 0.928 (0.909, 0.944) | 0.358 (0.327, 0.391) | 0.401 (0.369, 0.434) | 1.2 (1.1, 1.3) | 0.916 |
Abbreviations: AUC‐ROC, area under the receiver operating characteristic curve; CI, confidence interval; RT‐PCR, reverse transcription polymerase chain reaction.
There were 1530 tests of both BinaxNOW and RT‐PCR.
N = 1192 tests from 923 participants—284 participants were missing symptom onset dates.
N = 1526 tests from 1203 participants—4 participants were missing symptom data. Symptoms included tiredness, cough, loss of smell, dyspnea, myalgia, throat pain, chest pain, nausea/vomiting, diarrhea, abdominal pain, nasal congestion, chills, conjunctivitis, skin changes, rash, arthralgia, eye pain, bleeding, irritability, and calf pain.
N = 368 tests from 184 participants. Restricted to participants who had repeated tests.
N = 1359 tests from 1063 participants—144 participants were missing vaccination data.