Table 3.
Sensitivity analysis for daily supplementation of vitamin D
| Group | Study number; Patient number | Dose–response meta-analysis, RR (95% CI) | Pairwise Meta-analysis, RR (95% CI) | ||
|---|---|---|---|---|---|
| 400 IU/d | 800 IU/d | 1200 IU/d | |||
| Sensitivity analysis | |||||
| Daily administration [28, 29, 31, 33–35, 39, 40, 42, 44, 45, 50, 52, 54, 56–60, 62, 65, 69, 70] | 23; 8788 | 0.94 (0.87–1.02) | 0.92 (0.82–1.02) | 0.92 (0.84–1.02) | 0.92 (0.85–0.99) |
| Subgroups | |||||
| Age group (years) | |||||
| < 7 [39, 42, 52, 54, 56, 60, 69] | 7; 2614 | 0.88 (0.79–0.99) | 0.87 (0.77–0.98) | 0.88 (0.78–0.98) | 0.92 (0.84–1.01) |
| 7–17 [31, 33, 35, 44, 45, 65] | 6; 1312 | 0.70 (0.50–1.00) | 0.81 (0.64–1.03) | 0.94 (0.77–1.14) | 0.87 (0.67–1.12) |
| 18–65 [28, 29, 34, 40, 50, 57, 59, 70] | 8; 2445 | 0.93 (0.76–1.12) | 0.89 (0.72–1.11) | 0.88 (0.72–1.06) | 0.84 (0.70–1.02) |
| > 65 [58, 62] | 2; 2417 | NA | NA | NA | 0.91 (0.85–0.98) |
| Gender proportion (%) | |||||
| Male > 60[29, 33, 44, 45] | 4; 514 | NA | NA | NA | 0.84 (0.58–1.21) |
| Male ≤ 60 [28, 31, 34, 35, 39, 40, 42, 50, 52, 54, 56–60, 62, 65, 69, 70] | 19; 8274 | 0.97 (0.91–1.02) | 0.95 (0.88–1.03) | 0.95 (0.88–1.02) | 0.92 (0.86–0.99) |
| Comorbidity | |||||
| General [28, 29, 31, 35, 42, 44, 45, 52, 54, 56–58, 60, 62, 65, 69, 70] | 17; 7078 | 0.95 (0.86–1.05) | 0.93 (0.81–1.07) | 0.94 (0.84–1.06) | 0.92 (0.85–0.99) |
| Disease-specific [33, 34, 39, 40, 50, 59] | 6; 1710 | 0.70 (0.49–1.01) | 0.73 (0.53–1.00) | 0.75 (0.56–1.00) | 0.83 (0.66–1.04) |
| Baseline 25-hydroxyvitamin D levels (nmol/L) | |||||
| < 50 [35, 50, 54, 57, 70] | 5; 1528 | 0.84 (0.64–1.10) | 0.81 (0.60–1.10) | 0.79 (0.53–1.20) | 0.81 (0.59–1.11) |
| > 50 [28, 29, 34, 39, 40, 42, 45, 52, 56, 58–60, 62, 65, 66] | 15; 6335 | 0.95 (0.88–1.03) | 0.94 (0.84–1.04) | 0.94 (0.85–1.03) | 0.93 (0.87–0.99) |
| Trial duration (months) | |||||
| < 4 [28, 35, 44, 45, 57, 58, 69, 70] | 8; 1792 | 0.90 (0.52–1.57) | 0.87 (0.41–1.82) | 0.87 (0.75–1.69) | 0.79 (0.59–1.05) |
| 4–12 [29, 31, 33, 39, 42, 50, 52, 59, 60, 65] | 10; 2651 | 0.86 (0.76–0.97) | 0.84 (0.72–0.97) | 0.87 (0.76–1.00) | 0.89 (0.79–1.00) |
| > 12 [34, 40, 54, 56, 62] | 5; 4345 | NA | NA | NA | 0.99 (0.94–1.04) |
| Climatic zone | |||||
| Tropical or Subtropical [65, 69, 70] | 3; 854 | NA | NA | NA | 0.45 (0.14–1.48) |
| Temperate [28, 29, 31, 33–35, 39, 40, 42, 44, 45, 50, 52, 54, 56–60, 62] | 20; 7934 | 0.93 (0.86–1.00) | 0.90 (0.81–0.99) | 0.91 (0.82–1.00) | 0.92 (0.86–0.98) |
| Summer | |||||
| Summer-inclusive [34, 40, 42, 52, 54, 56–59, 62, 65, 69, 70] | 13; 6824 | 1.00 (0.96–1.05) | 1.00 (0.94–1.06) | 0.98 (0.92–1.05) | 0.96 (0.90–1.02) |
| Summer-sparing [28, 29, 31, 33, 35, 39, 44, 45, 50, 60] | 10; 1964 | 0.75 (0.65–0.87) | 0.72 (0.60–0.85) | 0.78 (0.67–0.91) | 0.83 (0.69–0.99) |
| Winter | |||||
| 8; 1658 | 0.69 (0.58–0.82) | 0.70 (0.59–0.82) | 0.80 (0.69–0.93) | 0.78 (0.68–0.92) | |
| Winter-non-dominant [33, 34, 40, 42, 50, 52, 54, 56–59, 62, 65, 69, 70] | 15; 7130 | 1.00 (0.95–1.04) | 0.99 (0.93–1.06) | 0.98 (0.92–1.05) | 0.96 (0.89–1.02) |
| Sensitivity analysis | |||||
| Type of ARIs | |||||
| Mixed upper and lower respiratory tract infections [29, 33–35, 42, 54, 56, 60, 62, 65] | 10; 4588 | 0.87 (0.74–1.01) | 0.87 (0.74–1.01) | 0.90 (0.79–1.02) | 0.88 (0.80–0.97) |
| Upper respiratory tract infections [28, 39, 40, 45, 50, 52, 54, 57–59] | 10; 3254 | 0.91 (0.83–1.00) | 0.87 (0.75–1.00) | 0.87 (0.74–1.01) | 0.97 (0.89–1.05) |
| Lower respiratory tract infections [54] | 1; 300 | NA | NA | NA | 0.94 (0.79–1.12) |
| Influenza [31, 44, 52, 58, 59, 69] | 6; 2125 | 0.90 (0.71–1.14) | 0.87 (0.64–1.18) | 0.89 (0.69–1.16) | 0.94 (0.80–1.10) |
ARI Acute respiratory infection, NA Not available