Table 1.
Characteristics of studies included in the meta-analysis.
| Study | Sample size | Population | Interventions | Vitamin D level | |
|---|---|---|---|---|---|
| Vitamin D group | Placebo group | ||||
| Naguib et al. (24) | 86 (vitamin D, 45; placebo, 41) | Patients undergoing valve replacement surgery | Oral dose of 2 μg/day alfacalcidol started 48 h before surgery and continued throughout the hospital stay | Baseline: 21.0 ± 11.2 ng/ml; Day 3: 23.4 ± 10.6 ng/ml | Baseline: 19.1 ± 9.5 ng/ml; Day 3: 16.5 ± 8.0 ng/ml |
| Sharma et al. (25) | 35 (vitamin D, 20; placebo, 15) | Acute traumatic brain injury patients | Oral dose of 120,000 IU vitamin D3 or placebo for 14 days | Baseline: 18.3 (14.5–23.0) ng/ml; Day 14: 39.2 (36.8–44.6) ng/ml | Baseline: 15.2 (11.8–26.9) ng/ml; Day 14: 27.3 (14.6–30.8) ng/ml |
| Ingels et al. (26) | 24 (vitamin D, 11; placebo, 13) | Critically ill patients in SICU | An IV loading dose of 200 μg and maintenance dose of 15 μg vitamin D3 per day, or IV injection of placebo for 10 days | Baseline: 9.2 (7.2–13.1) ng/ml; Day 10: about 16 ng/ml | Baseline: 6.8 (5.1–10.2) ng/ml; Day 10: about 8 ng/ml |
| Ginde et al. (21) | 1,078 (vitamin D, 538; placebo, 540) | Critically ill patients, more than 80% patients were medical patients | Single enteral does of 540,000 IU of vitamin D3 or placebo for 90 days | Baseline: 11.2 ± 4.8 ng/ml; Day 3: 46.9 ± 23.2 ng/ml | Baseline: 11.0 ± 4.7 ng/ml; Day 3: 11.4 ± 5.6 ng/ml |
| Miri et al. (27) | 40 (vitamin D, 22; placebo, 18) | Mechanically ventilated, adult ICU patients | Intramuscular injection of 300,000 IU vitamin D3 or placebo for 14 days | Baseline: 8.4 ± 6.8 ng/ml; Day 7: 10.5 ± 9.8 ng/ml | Baseline: 11.4 ± 18.2 ng/ml; Day 7: 11.2 ± 18.2 ng/ml |
| Karsy et al. (28) | 267 (vitamin D, 134; placebo, 133) | Neurocritical care patients | Single enteral does of 540,000 IU of vitamin D3 or placebo for 30 days | Baseline: 14.6 ± 4.2 ng/ml; Day 3: 20.8 ± 9.3 ng/ml | Baseline: 13.9 ± 4.6 ng/ml; Day 3: 12.8 ± 4.8 ng/ml |
| Hasanloei et al. (18) | 72 (oral vitamin D, 24; injection vitamin D, 24; control, 24) | Traumatic mechanical ventilated patients | Oral dose of 50,000 IU vitamin D3 daily or intramuscular injection of 300,000 IU vitamin D3 for 6 days, no placebo | Oral group: Baseline: 17.1 ± 4.5 ng/ml; After intervention: 28.6 ± 4.0 ng/ml; Injection group: baseline: 18.7 ± 3.3 ng/ml; After intervention: 29.4 ± 5.2 ng/ml | Baseline: 17.0 ± 3.3 ng/ml; After intervention: 16.1 ± 2.7 ng/ml |
| Parekh et al. (29) | 68 (vitamin D, 33; placebo, 35) | ICU patients after elective esophagectomy | Single oral preoperative (3–14 days) dose of 300,000 vitamin D3 or placebo | Baseline: 19.0(12.8–27.1) ng/ml; Preoperative: 29.9(25.4–37.0) ng/ml Postoperative day 3: 22.0(17.3–27.8) ng/ml |
Baseline: 18.5(14.2–27.6) ng/ml; Preoperative: 17.1(13.0–23.4) ng/ml Postoperative day 3: 11.2(7.8–16.2) ng/ml |
| Miroliaee et al. (30) | 46 (vitamin D, 24; placebo, 22) | Patients with ventilator-associated pneumonia | Intramuscular injection of 300,000 IU vitamin D3 or placebo for 28 days | Baseline: 17.1 ± 6.1 ng/ml; The vitamin D level increased 12.3 ± 8.3 ng/ml after 7 days | Baseline: 19.5 ± 4.6 ng/ml; The vitamin D level increased 1.2 ± 1.5 ng/ml after 7 days |
| Han et al. (17) | 30 (low-dose vitamin D, 9; high-dose vitamin D, 11; placebo, 10) | Mechanically ventilated patients, 16 in SICU and 14 in MICU | Low-dose vitamin D group received 50,000 IU of vitamin D3 daily for 5 days; High-dose vitamin D group received 100,000 IU of vitamin D3 daily for 5 days; Control group received placebo daily for 5 days | Low-dose vitamin D group: Baseline: 23.2 ± 7.8 ng/ml; Day 7: 45.0 ± 20.0 ng/ml High-dose vitamin D group: Baseline: 20.0 ± 7.3 ng/ml; Day 7: 55.0 ± 14.0 ng/ml | Baseline: 21.5 ± 12.2 ng/ml; Day 7: NR |
| Quraishi et al. (19) | 30 (low-dose vitamin D, 10; high-dose vitamin D, 10; placebo, 10) | Patients with sepsis, 16 in MICU and 14 in SICU | Low-dose vitamin D group received 200,000 IU of vitamin D3 daily; High-dose vitamin D group received 400,000 IU of vitamin D3 daily; Control group received placebo daily | Low-dose vitamin D group: Day 1: 15 (12–20) ng/ml; Day 5: 22 (16–25) ng/ml High-dose vitamin D group: Day 1: 17 (13–25) ng/ml; Day 5: 29 (23–41) ng/ml | Day 1: 19 (13–22) ng/ml; Day 5: 19 (11–23) ng/ml |
| Amrein et al. (20) | 475 (vitamin D, 237; placebo, 238) | Critically ill patients, more than 75% patients were surgical or neurologic patients | Vitamin D3 or placebo was given orally or via nasogastric tube once at a dose of 540,000 IU followed by monthly maintenance doses of 90,000 IU for 5 months | Baseline: 13.0 ± 4.0 ng/ml; Day 3: 33.5 ± 18.7 ng/ml; Day 7: 35.5 ± 20.6 ng/ml | Baseline: 13.1 ± 4.3 ng/ml; Day 3: 13.9 ± 5.0 ng/ml; Day 7: 14.5 ± 5.1 ng/ml |
| Leaf et al. (31) | 67 (vitamin D, 36; placebo, 31) | Patients with severe sepsis or septic shock, 38 in SICU and 29 in MICU | Single intravenous dose of calcitriol, 2 mg, or equal volume of saline | Baseline: 14.1 (9.3–36.4) pg/ml; 6 h: 75.7 (52.1–115.5) pg/ml | Baseline: 13.7 (10.7–30.8) pg/ml; 6 h: 16.9 (9.0–26.9) pg/ml |
| Amrein et al. (32) | 25 (vitamin D, 12; placebo, 13) | Critically ill patients in MICU | 540,000 IU of vitamin D3 or placebo orally or via feeding tube | Baseline: 13.1 ng/ml; Day 3: 33.1 ng/ml; Day 7: 38.2 ng/ml | Baseline: 14.1 ng/ml; Day 3: 15.0 ng/ml; Day 7: 13.7 ng/ml |
IU, international unit; SICU, surgical intensive care unit; IV, injection of vein; MICU, medical intensive care unit; ICU, intensive care unit.