TABLE 1.
The characteristics of eligible studies.
| Study and Country | Type of study and patients source | Intervention and Control | Vitamin D supplements | Control | Number of deaths/Intubation or Mechanical ventilation requirement/ICU admission: number of intervention or control | ||
| Age | 25(OH)D levels before/after treatment(ng/ml) | Age | 25(OH)D levels before/after treatment(ng/ml) | ||||
| Elamir et al. (8), Israel | RCT, Hospitalized patients | Oral 0.5 ug calcitriol per day. vs. Without vitamin D supplements | 69 ± 18 | NA | 64 ± 16 | NA | 0/0/5: 25 vs. 3/2/8: 25 |
| Cannata-Andía et al. (9), Multicentre | RCT, Hospitalized patients | A single oral dose of 100,000 IU cholecalciferol vs. Without vitamin D supplements | 59.0(49.0, 70.0) | 17.0(11.8,22.0)/29.0 (20.3,35.0) |
57.0(45.0, 67.0) | 16.1(11.5, 22.0)/16.4(11.8, 23.0) | 22/NA/47: 274 vs. 15/NA/44: 269 |
| Javier Mariani et al. (10), Argentina | RCT, Hospitalized patients | A single oral dose of 500,000 IU of vitamin D3 vs. Placebo | 59.8 ± 10.7 | 32.5 (27.2–44.2)/102 (85.2 to 132.2)a |
58.3 ± 10.6 | 30.5(22.5–36.2)/30.0 (27.5–31.0)a | 5/5/9: 115 vs. 2/6/11: 103 |
| IMurai et al. (20), Brazil | RCT, Hospitalized patients | A single oral dose of 200,000 IU cholecalciferol vs. Placebo | 56.5 ± 13.8 | 21.2 ± 10.1/44.4 ± 15.0 |
56 ± 15 | 20.6 ± 8.1/19.8 ± 10.5 |
9/9/19: 119 vs. 6/17/25: 118 |
| Jessie Zurita-Cruz et al. (21), Mexico | RCT, Hospitalized patients | 1,000 IU/day of Cholecalciferol for children younger than 1 year and 2,000 IU/day for 1–17 years. vs. Without vitamin D supplements | 10.66(4.41–14.62) | 13.8(10.75–18.35)/NA | 13.95(7.35-14.87) | 11.4(8.7–13.1)/NA | 1/NA/NA:20 vs. 6/NA/NA:25 |
| Mikhail V. Bychinin et al. (22), Russia | RCT, Hospitalized patients with hypovitaminosis D | 60,000 IU cholecalciferol once per 7 days, followed by daily doses of 5,000 IU vs. Placebo | 64.5 (57–71) | 9.6(5.6–21)/20.6 (11.8–24.8) | 63.5 (54–81) | 11.2(8.6–14.9)/10.4 (5.8–12.2) | 19/33/NA: 52 vs. 27/37/NA: 54 |
| Castillo et al. (23), Spain | RCT, Hospitalized patients | Oral 0.532 mg Calcifediol on day 1, 0.266 mg on days 3 and 7, then weekly. vs. Without vitamin D supplements. | 53.14 ± 10.77 | NA | 52.77 ± 9.35 | NA | 0/NA/1:50 vs. 2/NA/13: 26 |
| Sophie De Niet et al. (24), Belgium | RCT, Hospitalized patients with hypovitaminosis D | Oral 25,000 IU of Cholecalciferol over 4 consecutive days. Then, 25,000 IU per week up to 6 weeks. vs. Placebo | 63.24 ± 14.46 | 17.87 ± 10.15/NA | 68.73 ± 10.97/NA | 16.87 ± 9.48/NA | 3/NA/5: 22 vs. 4/NA/2: 21 |
| Annweiler C et al. (5), French | Cohort study, hospitalized patients | Oral 50,000 IU cholecalciferol per month, or 80,000 IU or 100,000 IU, or 200,000 IU every 2–3 months, or 800 IU daily. vs. Without vitamin D supplements | 87.7 ± 5.4 | 24.64 ± 14.16/NA | 88.6 ± 5.7 | 29.56 ± 12.84/NA | 16/NA/NA:67 vs. 13/NA/NA: 28 |
| Annweiler C et al. (6), French | Cohort Study, COVID-19 patients in the nursing home | Oral 80,000 IU cholecalciferol vs. Without vitamin D supplements | 87.7 ± 9.3 | NA | 87.4 ± 7.2 | NA | 10/NA/NA: 57 vs. 5/NA/NA: 9 |
| Annweiler G et al. (11), France | Cohort Study, Hospitalized patients | Oral 80,000 IU cholecalciferol within a few hours of the diagnosis vs. Without vitamin D supplements | 85 (84–89) | NA | 88 (84–92) | NA | 3/NA/NA:45 vs. 10/NA/NA: 32 |
| Güven et al. (12), Turkey | Cohort Study, Hospitalized patients | Inject 300,000 IU cholecalcifero in the first 24 h of admission vs. Without vitamin D supplements | 74 (60–81) | 6.65 (5.06–9.1)/NA | 75 (62–83) | 7.14 (5.17–8.21)/NA | 43/44/NA:113 vs. 30/31/NA:62 |
| Xavier et al. (13), Spain | Cohort Study, Hospitalized patients | Oral 532 μg calcifediol on day 1 plus 266 μg on days 3, 7, 15, and 30. vs. Without vitamin D supplements | 61.81 ± 15.5 | 13(8–24)/NA | 62.41 ± 17.2 | 12 (8–19)/NA | 21/NA/20:447 vs. 47/NA/82: 391 |
| Soliman et al. (25), Egypt | Cohort Study, Hospitalized patients with type 2 diabetes | Inject a single dose of 200,000 IU cholecalciferol vs. Placebo | 71.30 ± 4.16 | 10.4 ± 1.3/20.54 ± 3.00 | 70.19 ± 4.57 | 21.17 ± 3.96/21.23 ± 3.98 | 7/14/NA: 40 vs. 3/7/NA: 16 |
| Alcala-Diaz et al. (26), Spain | Cohort Study, Hospitalized patients | Oral 0.532 mg calcifediol at day 0, 0.266 mg on days 3 and 7, and then weekly. vs. Without vitamin D supplements. | 69 ± 15 | NA | 67 ± 16 | NA | 4/3/NA: 79 vs. 90/26/NA: 458 |
| Jevalikar et al. (27), India | Cohort Study, Hospitalized patients | A single oral dose of 60,000 IU cholecalciferol vs. Without vitamin D supplements. | 45.5 ± 18.2 | <20/NA | 48.8 ± 14.7 | <20/NA | 1/NA/16:128 vs. 3/NA/13: 69 |
aOnly 16 participants from two study sites had their blood samples drawn for measurement of serum 25(OH)D. Calcifediol, 25-hydroxyvitamin D3; calcitriol, 1,25-Dihydroxyvitamin D3; cholecalciferol, vitamin D3; IQR, interquartile range; NA, not available. This table presented data as mean ± SD, or median (IQR).