Table 2.
Comparison of laboratory test, imaging results, and severity in patients grouped by the first RT-PCR result.
| Variable | Positive RT-PCR | Negative RT-PCR | P |
|---|---|---|---|
| Laboratory test, median [IQR] | |||
| PO2 at arrival (mm Hg) | 77.00 [60.00–94.75] | 71.00 [61.00–82.00] | 0.093# |
| PCO2 at arrival (mm Hg) | 34.50 [31.00–38.00] | 35.00 [32.00–38.30] | 0.33# |
| P/F at arrival | 314.29 [235.71–392.86] | 319.05 [250.00–369.05] | 0.748# |
| Total WBC (K/μL) | 6.02 [4.59–8.13] | 7.62 [5.12–11.50] | 0.002# |
| Lymphocytes (U/μL) | 1324.50 [1009.50–1789.50] | 1120.00 [820.00–1710.00] | 0.013# |
| LDH (U/L) | 330.50 [218.50–449.25] | 288.50 [243.75–380.75] | 0.526# |
| Imaging results, n (%) | |||
| Chest X-ray (n = 271) | <0.001° | ||
| Pneumonia consolidation | 40 (19.0) | 15 (24.6) | |
| Interstitial syndrome | 18 (8.6) | 19 (31.1) | |
| Aspecific findings | 87 (41.4) | 15 (24.6) | |
| Normal CXR | 65 (31.0) | 12 (19.7) | |
| Lung ultrasound (n = 234) | <0.001§ | ||
| Consolidation | 54 (30.3) | 13 (23.2) | |
| Monolateral interstitial syndrome | 41 (23.0) | 6 (10.7) | |
| Bilateral interstitial syndrome | 34 (19.1) | 26 (46.4) | |
| Pleural effusion | 0 (0.0) | 7 (12.5) | |
| Normal lung ultrasound | 49 (27.5) | 4 (7.1) | |
| CT scan (n = 70) | 0.012§ | ||
| Typical pattern | 16 (80.0) | 29 (58.0) | |
| Atypical pattern | 0 (0.0) | 5 (10.0) | |
| Undetermined | 2 (10.0) | 16 (32.0) | |
| Normal CT scan | 2 (10.0) | 0 (0.0) | |
| Irregular pleural line (n = 243) | 0.751° | ||
| No | 157 (84.0) | 48 (85.7) | |
| Yes | 30 (16.0) | 8 (14.3) | |
| COVID-19 severity (NIH classification) | 0.001§ | ||
| Asymptomatic | 16 (7) | 0 (0) | |
| Mild illness | 43 (18) | 3 (5) | |
| Moderate illness | 90 (38) | 35 (53) | |
| Severe illness | 70 (30) | 26 (39) | |
| Critical illness | 17 (7) | 2 (3) | |
Abbreviations: PO2 = oxygen partial pressure; PCO2 = partial pressure of carbon dioxide; P/F ratio = PO2/fraction of inspired oxygen (FiO2); wbc = white blood cells, LDH = lactate dehydrogenases, CT = computed tomography.
Data are described as absolute frequencies and percentages (in brackets) for categorical variables and as median and interquartile range [IQR] for quantitative variables. Comparisons are made with: #: Wilcoxon rank-sum test; °: Chi-squared test; §: Fisher's exact test.