Table S4. Assessment of study design, populations, supplementation and methodological quality.
| Study characteristics | n | % |
|---|---|---|
| Study design† | ||
| RCT/qRCT | 13 | 76 |
| Single arm | 3 | 18 |
| Controlled, other | 1 | 6 |
| Randomized trial quality†,‡ | ||
| Low risk | 11 | 65 |
| Medium risk/unclear | 3 | 18 |
| High risk | 3 | 18 |
| Age groups§ | ||
| Neonates | 4 | 22 |
| Infants | 4 | 22 |
| Toddlers | 6 | 33 |
| Schoolers | 16 | 89 |
| Adolescents | 15 | 83 |
| Population§ | ||
| Healthy/subclinical VDD | 8 | 42 |
| Classical diseases | 3 | 16 |
| Non-classical diseases | 8 | 42 |
| Dosing regimen¶ | ||
| Constant | 18 | 64 |
| Variable | 10 | 36 |
| Dosing groups¶ | ||
| RDA/AI-999 | 3 | 11 |
| 1,000–3,999 | 5 | 18 |
| 4,000–39,999 | 11 | 39 |
| ≥40,000 | 9 | 32 |
| Frequency¶ | ||
| Daily | 18 | 64 |
| Intermittent/single dose | 8 | 29 |
| Weekly/biweekly | 2 | 7 |
(q)RCT, (Quasi) randomized controlled trial. †, values represent the number of trials, and the percentage out of the 17 identified trials; ‡, studies were assessed using Cochrane risk of bias tool (Higgins & Green, 2008); §, numbers of populations out of 19. For age, numbers will add up to more than 19 populations as some included children from two or more groups; ¶, number of high-dose vitamin D arms out of 28 identified in eligible studies.