Table 4. Pooled specificity of Ag-RDTs for detection of SARS-CoV-2 on subgroup analysis.
| Subgroups | Pooled Specificity (95% CI) | Number of studies analyzed | Total number of events | Heterogeneity | ||
|---|---|---|---|---|---|---|
| I2 | p-Value | |||||
| Based on clinical presentation at the time of testing | Symptomatic | 100 (0–100) | 2 | 127 | 0 | 1 |
| Asymptomatic | 99.8 (98.9–100) | 2 | 659 | 0 | 1 | |
| Symptomatic/ Asymptomatic | 99.1 (97.1–99.8) | 8 | 2716 | 84 | <0.01 | |
| Based on type of Commercial Ag-RDT used | SD Biosensor test | 99.1 (96.3–96.8) | 7 | 2398 | 83 | <0.0001 |
| Other | 99.7 (99.2–99.9) | 5 | 1104 | 0 | <0.01 | |
| Based on Ct cut off value for positive RT-PCR | ≤40 | 100 (0–100) | 2 | 127 | 0 | 1 |
| <40 | 96.9 (89.3–99.1) | 2 | 566 | 92 | <0.01 | |
| <35 | 100 (0–100) | 1 | 265 | NA | NA | |
| <32 | 99.8 (98.8–100) | 1 | 593 | NA | NA | |
| Not specified | 99.4 (97.4–99.9) | 6 | 1951 | 84 | <0.01 | |
| Based on risk of bias and concerns regarding applicability for patient selection | Low | 99.5 (98.3–99.8) | 9 | 2999 | 85 | <0.01 |
| High | 99.8 (62.4–100.0) | 3 | 503 | 0 | 1 | |
| Based on concordance of samples used for index test and reference standard | Yes | 99.4 (97.2–99.9) | 9 | 2250 | 76 | <0.01 |
| No | 99.7 (98.2–99.9) | 3 | 1252 | 42 | 0.18 | |