Table 2.
Chest X-ray analysis results obtained by two independent reviewers (reviewer 1, a thoracic radiologist with 5 years of experience; reviewer 2, a fourth-year radiology resident) in 340 patients with confirmed COVID-19
| Reviewer 1 | Reviewer 2 | Inter-rater agreement | p | |
|---|---|---|---|---|
| Normal CXR | 6/340(2%) | 7/340 (2%) | κ = 0.92 [0.77–1.00] | < 0.001 |
| Type of parenchymal opacity | κ = 0.90 [0.85–0.95] | < 0.001 | ||
| GGO | 96/340 (28%) | 100/340 (29%) | ||
| Consolidation | 3/340 (1%) | 3/340 (1%) | ||
| GGO and consolidation | 235/340 (69%) | 230/340 (68%) | ||
| None | 6/340 (2%) | 7/340 (2%) | ||
| No. lung zones involved | 4 [3-6] | 4 [4-6] | ICC = 0.86 [0.83–0.88] | < 0.001 |
| ≥ 2 lung zones involved | 321/340 (94%) | 323/340 (95%) | κ = 0.71 [0.53–0.88] | < 0.001 |
| Distribution 1 | κ = 0.78 [0.69–0.86] | < 0.001 | ||
| Central | 16/334 (5%) | 8/333 (3%) | ||
| Peripheral | 99/334 (30%) | 91/333 (27%) | ||
| Neither | 219/334 (65%) | 234/333 (70%) | ||
| Distribution 2 | κ = 0.80 [0.72–0.87] | < 0.001 | ||
| Superior | 3/334 (1%) | 2/333 (1%) | ||
| Medium | 30/334 (9%) | 22/333 (6%) | ||
| Inferior | 75/334 (22%) | 69/333 (21%) | ||
| None | 226/334 (68%) | 240/333 (72%) | ||
| Distribution 3 | ||||
| Bilateral | 312/334 (93%) | 314/333 (94%) | κ = 0.71 [0.55–0.87] | < 0.001 |
| Pleural effusion | 53/340 (16%) | 38/340 (11%) | κ = 0.79 [0.69–0.88] | < 0.001 |
| Nodules | 3/340 (1%) | 1/340 (0.3%) | κ = 0.50 [− 0.10 to 1.00] | 0.104 |
| Brixia score [18] | 7 [4–11] | 7 [4–11] | ICC = 0.91 [0.89–0.93] | < 0.001 |
| % of lung involvement | 55 [30–76] | 54 [28–75] | ICC = 0.95 [0.93–0.96] | < 0.001 |
The frequency of individual CXR features is reported as number of positive cases or percent distribution. The Brixia score and percentage of lung involvement are shown in percent terms and median [IQR], respectively. Inter-rater agreement is shown as weighted Cohen’s kappa (individual CXR features), or intraclass correlation coefficient (no. of lung zones involved, Brixia score, and percentage of lung involvement), with pertinent 95% CI. CXR, chest X-ray; GGO, ground-glass opacity; IQR, interquartile range