Table 3.
Characteristics of individual studies included in the meta-analysis comparing vitamin C vs. control.
| Author/Country | Study design | Administered vitamin C regimen | Number of critically ill patients (n) | Female sex (%) | Age (years) | Baseline severity | Hypertension (%) | Diabetes Mellitus (%) | Coronary heart disease (%) |
|---|---|---|---|---|---|---|---|---|---|
| Al Sulaiman/Saudi Arabia (23) | Observational retrospective, multi-center | Enterally 1 g q24h | 739 | 15.2 vs. 30.0 |
60.5 ± 15.1 vs. 60.7 ± 14.8 |
4.0 (2.0–6.0) vs. 5.0 (3.0–8.0) |
56.4 vs. 56.9 |
60.3 vs. 61.2 |
8.2 vs. 8.6 |
| Beigmohammadi/Iran (32) | Randomized controlled trial, single-center | Enterally 2 g q24h | 60 | 50.0 vs. 46.7 |
51.0 ± 17.3 vs. 53.0 ± 7.0 |
7.0 ± 2.3 vs. 7.0 ± 3.0 |
NA | NA | NA |
| Darban/Iran (31) | Observational retrospective, single-center | IV 2 g q6h | 20 | NA | NA | NA | NA | NA | NA |
| Gao*/China (24) | Observational retrospective, single-center | IV 6 g q12h on 1st day; then, IV 6 g q24h for the next 4 days | 76 | 54.3 vs. 53.3 |
63.0 (54.0–71.0) vs. 57.0 (49.0–67.0) |
NA | 34.8 vs. 20.0 |
23.9 vs. 13.3 |
6.5 vs. 6.7 |
| Gavrielatou/Greece | Observational retrospective, single-center | IV 1 g q8h for 4 days; then, IV 500 mg q8h for 3 days; and, finally, IV 500 mg q12h for 3 days | 113 | 30.0 vs. 24.3 |
70.5 (58.0–75.0) vs. 69.0 (55.0–77.0) |
4.0 (4.0–5.3) vs. 4.0 (4.0–5.0) |
60.0 vs. 53.4 |
30.0 vs. 22.3 |
30.0 vs. 24.3** |
| JamaliMoghadamSiahkali/ Iran (25) |
Randomized controlled trial, single-center | IV 1.5 g q6h for 5 days | 60 | 50.0 vs. 50.0 |
57.5 ± 18.2 vs. 61 ± 15.9 |
3.6 ± 1.4 vs. 3.4 ± 1.5 |
50.0 vs. 33.3 |
40.0 vs. 36.7 |
13.3 vs. 23.3 |
| Krishnan/United States (26) | Observational retrospective, multi-center | NA | 152 | NA | NA | NA | NA | NA | NA |
| Kumari/Pakistan (27) | Randomized controlled trial, single-center | IV 50 mg/kg q24h | 150 | NA | 53 ± 11 vs. 53 ± 12 |
NA | NA | NA | NA |
| Li/United States (28) | Observational retrospective, single-center | IV 1.5 g q6h for up to 4 days | 32 | 63.0 vs. 63.0 |
64.1 ± 8.3 vs. 64.9 ± 11.8 |
6.6 ± 3.5 vs. 9.4 ± 3.2 |
75.0 vs. 54.2 |
50.0 vs. 45.8 |
12.5 vs. 4.2 |
| Zhang/China (29) | Randomized controlled trial, multi-center | IV 12 g q12h for 7 days | 56 | 44.4 vs. 24.1 |
66.3 ± 11.2 vs. 67 ± 14.3 |
14.0 (11.0–16.0) vs. 13.0 (9.5–15.0) |
37.0 vs. 51.7 |
29.6 vs. 32.1 |
14.8 vs. 27.6 |
| Zheng/China (30) | Observational retrospective, single-center | IV 2–4 g q24 24h after admission or during follow up before discharge | 397 | 40.0 vs. 49.5 |
67.5 (58.0–74.8) vs. 67.0 (62.0–74.0) |
NA | 18.6 vs. 21.4 |
15.7 vs. 15.6 |
4.3 vs. 6.7 |
n, number; IV, intravenous; h, hours; NA, not applicable.
Data are presented as mean ± standard deviation or median (interquartile range).
Baseline severity is presented as Sequential Organ Failure Assessment Score (SOFA) (23, 28) as Acute Physiology And Chronic Health Evaluation (APACHE II) (29) or other (25, 32).
*
Data from the entire cohort of patients (not only critically ill) are presented.
**
Numbers include coronary heart disease along with congestive heart failure and cardiomyopathies.