TABLE 2.
Effect of circulating 25-hydroxyvitamin D concentrations on bone health outcomes, falls, and performance measures1
| Group | Health effect | Study type and ratio of new to total studies2 | Quality of new RCTs3 |
| Infants and young children (adapted from reference 13, Table 1, pp 35–40) | Rickets | RCT, 1:1 | 1 |
| Before-after, 0:4 | |||
| Case control, 6:8 | |||
| Total, 7:13 | |||
| Infants (adapted from reference 13, Table 2, pp 44–50) | Bone health | RCT, 0:3 | |
| Case-control, 3:4 | |||
| Total, 3:7 | |||
| Older children and adolescents (adapted from reference 13, Table 3, pp 55–59) | Bone health | RCT, 1:2 | 4 |
| Cohort, 3:3 | |||
| Case control, 1:1 | |||
| Before-after, 1:1 | |||
| Total, 6:7 | |||
| Pregnant and lactating women (adapted from reference 13, Table 4, pp 64–67) | Bone health | Cohort, 3:3 | — |
| Before-after, 1:1 | |||
| Total, 4:4 | |||
| Postmenopausal women and older men (adapted from reference 13, Table 6, pp 78–86) | Fractures | Cohort, 2:3 | — |
| Case control, 8:13 | |||
| Total, 10:16 | |||
| Postmenopausal women and older men (adapted from reference 13, Table 7, pp 87–92) | Falls | RCT, 2:2 | 3, 5 |
| Cohort, 3:3 | |||
| Case control, 1:1 | |||
| Total, 6:6 | |||
| Postmenopausal women and older men (adapted from reference 13, Table 7, pp 87–92) | Performance measures4 | RCT, 2:3 | 4, 5 |
| Cohort, 4:4 | |||
| Total, 6:7 | |||
| Postmenopausal women and older men (adapted from reference 13, Table 8, pp 93–101) | BMD, BMC | RCT, 4:6 | 4, 4, 4, 5 |
| Cohort, 6:7 | |||
| Case control, 5:6 | |||
| Total, 15:19 |
Data adapted from Cranney et al, 2007 (13). RCT, randomized clinical trial; BMD, bone mineral density; BMC, bone mineral content. “Before-after” refers to studies in which vitamin D status was assessed before and after a vitamin D intervention. “Cohort” refers to observational studies with prospective cohort designs.
“New” refers to references not likely to have been available to the 1997 Dietary Reference Intake Committee and included all studies published after 1997 and studies published during 1997 that were not cited in the master reference list for the 1997 Institute of Medicine's report “Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride” (3) and excluded studies published before and during 1996 and studies published during 1997 that were cited in the master reference list for the 1997 Institute of Medicine's report.
The study quality for RCTs was assessed in the systematic review (13) by using the validated Jadad scale with a score of ≥3 (out of a possible 5) indicating studies of higher quality.
Performance measures included parathyroid hormone, muscle strength, independence index, postural sway, reaction time, aggregate functional performance time, quadriceps strength, ability to rise from a chair, static balance, 8-ft (2.44 m) walk, timed supine-to-stand test, quadriceps strength, and walking speed.