Diagnostic accuracy metrics for CXR and CT chest with RT-PCR for SARS-CoV-2, as the reference standard
| Chest X-ray | CT chest | Mean difference | P value | |
| Total (n) | 860 | 302 | ||
| True positives (n) | 305 | 162 | – | – |
| False positives (n) | 125 | 55 | – | – |
| True negatives (n) | 187 | 56 | – | – |
| False negatives (n) | 243 | 29 | – | – |
| Apparent prevalence (95% CI) | 0.50 (0.47 to 0.53) | 0.72 (0.66 to 0.77) | 0.22 (0.04 to 0.21) | <0.0001** |
| True prevalence (95% CI) | 0.64 (0.60 to 0.67) | 0.63 (0.58 to 0.69) | −0.00 (−0.09 to 0.03) | 0.111 |
| Sensitivity (95% CI) | 0.56 (0.51 to 0.60) | 0.85 (0.79 to 0.90) | 0.29 (0.19 to 0.38) | <0.0001** |
| Specificity (95% CI) | 0.60 (0.54–0.65) | 0.50 (0.41 to 0.60) | −0.10 (−0.25 to 0.04) | 0.119 |
| Positive predictive value (95% CI) | 0.71 (0.66 to 0.75) | 0.75 (0.68 to 0.80) | 0.04 (−0.06 to 0.14) | 0.492 |
| Negative predictive value (95% CI) | 0.43 (0.39 to 0.48) | 0.66 (0.55 to 0.76) | 0.22 (0.06 to 0.37) | 0.005* |
| Positive likelihood ratio (95% CI) | 1.39 (1.19 to 1.62) | 1.71 (1.41 to 2.08) | 0.32 (−0.22 to 0.89) | 0.258 |
| Negative likelihood ratio (95% CI) | 0.74 (0.64 to 0.84) | 0.30 (0.21 to 0.44) | −0.44 (−0.64 to −0.21) | 0.022* |
| Diagnostic accuracy (95% CI) | 0.57 (0.54 to 0.61) | 0.72 (0.66 to 0.77) | 0.15 (0.06 to 0.23) | <0.0001** |
*Significant difference at the <0.05 level; **significant difference at the <0.0001 level.
CXR, chest X-ray; RT-PCR, reverse transcriptase PCR.