Table 1.
Baseline characteristics of patients who received vitamin C or not, before and after inverse probability treatment weighting (IPTW)
| Characteristics | Unweighted patients | Weighted patients | ||||||
|---|---|---|---|---|---|---|---|---|
| Yes | No | Overall | Absolute SMD | Yes | No | Overall | Absolute SMD | |
| (N = 70) | (N = 327) | (N = 397) | (N = 73) | (N = 323) | (N = 396) | |||
| Age, median (IQR), y | 67.50 (58.00–74.75) | 67.00 (62.00–74.00) | 67.00 (61.00–74.00) | 0.08 | 69.97 (64.97–75.90) | 67.00 (62.00–74.00) | 68.00 (62.00–74.00) | 0.10 |
| Sex, No. (%) | ||||||||
| Female | 28 (40.0) | 162 (49.5) | 190 (47.9) | 0.19 | 34.9 (47.9) | 153.8 (47.7) | 188.8 (47.7) | 0.01 |
| Male | 42 (60.0) | 165 (50.5) | 207 (52.1) | 38.0 (52.1) | 168.8 (52.3) | 206.8 (52.3) | ||
| Comorbidity, No. (%) | ||||||||
| Hypertension | 13 (18.6) | 70 (21.4) | 83 (20.9) | 0.07 | 22.7 (31.1) | 69.5 (21.5) | 92.2 (23.3) | 0.24 |
| Coronary heart disease | 3 (4.3) | 22 (6.7) | 25 (6.3) | 0.10 | 3.8 (5.3) | 19.6 (6.1) | 23.5 (5.9) | 0.04 |
| Chronic lung diseasea | 4 (5.7) | 15 (4.6) | 19 (4.8) | 0.05 | 2.8 (3.8) | 15.7 (4.9) | 18.5 (4.7) | 0.05 |
| Cerebral infarction | 2 (2.9) | 8 (2.4) | 10 (2.5) | 0.03 | 3.8 (5.2) | 9.2 (2.8) | 12.9 (3.3) | 0.15 |
| Diabetes | 11 (15.7) | 51 (15.6) | 62 (15.6) | <0.01 | 12.1 (16.6) | 50.0 (15.5) | 62.1 (15.7) | 0.03 |
| Cancer | 6 (8.6) | 16 (4.9) | 22 (5.5) | 0.16 | 3.3 (4.6) | 17.3 (5.4) | 20.6 (5.2) | 0.04 |
| Initial laboratory tests, median (IQR)b | ||||||||
| Neutrophil (×109/L) | 4.70 (3.29–6.79) | 3.46 (2.72–4.69) | 3.62 (2.72–5.03) | 0.66 | 3.94 (2.87–5.12) | 3.57 (2.73–4.92) | 3.67 (2.73–5.00) | 0.05 |
| Lymphocyte (×109/L) | 0.92 (0.62–1.33) | 1.23 (0.84–1.59) | 1.14 (0.81–1.58) | 0.32 | 1.08 (0.86–1.79) | 1.18 (0.81–1.58) | 1.17 (0.81–1.60) | 0.02 |
| Lactate dehydrogenase (U/L) | 276.00 (213.00–370.00) | 212.00 (175.25–264.75) | 219.00 (181.00–280.50) | 0.76 | 225.35 (198.06–280.00) | 216.59 (179.00–273.88) | 219.00 (184.00–276.28) | 0.09 |
| C-Reactive protein (mg/L) | 25.55 (7.13–99.10) | 7.19 (3.14–33.58) | 10.07 (3.14–39.67) | 0.65 | 14.00 (3.14–30.83) | 8.99 (3.14–41.19) | 10.80 (3.14–38.99) | 0.02 |
| Alanine aminotransferase (U/L) | 27.00 (17.00–41.00) | 25.00 (17.00–39.00) | 25.00 (17.00–40.00) | 0.06 | 23.29 (16.00–50.52) | 26.00 (18.00–41.00) | 26.00 (17.00–42.17) | 0.06 |
| Creatinine (μmol/L) | 74.00 (61.40–99.20) | 74.00 (63.90–86.17) | 74.00 (63.00–88.00) | 0.14 | 77.09 (62.71–90.40) | 73.46 (63.00–86.00) | 74.00 (63.00–86.70) | 0.03 |
| D-dimer (mg/L) | 1.17 (0.33–4.22) | 0.75 (0.32–1.84) | 0.82 (0.32–2.04) | 0.40 | 1.12 (0.20–1.90) | 0.82 (0.34–2.01) | 0.84 (0.32–1.92) | 0.05 |
| Medications at baseline, no. (%) | ||||||||
| Arbidol | 62 (88.6) | 300 (91.7) | 362 (91.2) | 0.11 | 66.8 (91.5) | 295.7 (91.7) | 362.5 (91.6) | <0.01 |
| Interferon α-2b | 25 (35.7) | 34 (10.4) | 59 (14.9) | 0.71 | 12.6 (17.3) | 46.7 (14.5) | 59.3 (15.0) | 0.08 |
| Ribavirin | 21 (30.0) | 37 (11.3) | 58 (14.6) | 0.53 | 11.0 (15.1) | 46.9 (14.5) | 57.8 (14.6) | 0.02 |
| LMWH | 23 (32.9) | 53 (16.2) | 76 (19.1) | 0.42 | 16.5 (22.7) | 58.8 (18.2) | 75.3 (19.0) | 0.11 |
| Antibiotics | 64 (91.4) | 248 (75.8) | 312 (78.6) | 0.38 | 56.3 (77.3) | 252.8 (78.3) | 309.1 (78.1) | 0.03 |
| ARB/ACEI | 5 (7.1) | 37 (11.3) | 42 (10.6) | 0.14 | 6.1 (8.4) | 33.8 (10.5) | 39.9 (10.1) | 0.07 |
| Chinese medicine | 56 (80.0) | 271 (82.9) | 327 (82.4) | 0.08 | 57.1 (78.3) | 266.0 (82.5) | 323.2 (81.7) | 0.11 |
Abbreviations: SMD, standardized mean difference; IQR, interquartile range; LMWH, low molecular weight heparin; ARB, angiotensin-receptor blocker; ACEI, angiotensin-converting enzyme inhibitor.
aChronic lung disease was defined as a chronic obstructive pulmonary disease (COPD), asthma, or chronic bronchitis.
bIn the unweighted analysis, data on the D-dimer level were missing for 65 patients, on the C-reactive protein level for 11, on the lactate dehydrogenase level for 6, on the creatinine level for 4, on the ALT for 4, on the neutrophil count for 3, and on the lymphocyte count for 3. Multiple imputation was used to handle missing data in the inverse probability treatment weighting analysis.