Table 3

Supplementation duration and adherence
Adherence Placebo Vitamin D p
Mean ± SD Median Range (min, max) Mean ± SD Median Range (min, max)
Time on study, weeks 9.7 ± 3.5 10.5 (0, 18) 9.8 ± 3.3 10 (0, 18) 0.871
Total supplement doses administered 10.5 ± 3.5 11 (1, 19) 10.6 ± 3.3 11 (1, 17) 0.83
Total vitamin D administered, mcg - - - 9469 ± 2424 9625 (875, 14000) -
Adherence, %2 99.2 ± 2.7 100 (84.6, 100) 99.4 ± 2.9 100 (80, 100) 0.79
Participants who received 100% of scheduled doses, n (%)3 68 (91.9%) 69 (94.5%) 0.533

1 p-value for Student’s t-test for equality of means.

2 Adherence = (number of doses received divided by the number of doses scheduled) x 100. Analysis shown included participants who contributed 25(OH)D measurements beyond baseline (n = 74 and n = 73 in placebo and vitamin D groups, respectively). Adherence for participants for whom delivery specimens were available was similar: mean of 99.1% in the placebo group (n = 63) and 99.3% in the vitamin D group (n = 67). With respect to longitudinal analyses of changes in 25(OH)D over time, 206/219 serum specimens (93.5%) in the vitamin D group and 201/213 (94.4%) specimens in the placebo group were preceded by 100% dose adherence.

3 Proportions shown were calculated among participants who contributed 25(OH)D measurements beyond baseline (74 in placebo group or 73 in the vitamin D group); p value for chi-square test for proportions. Proportions in the subgroup of participants for whom delivery specimens were available were similar: 90.5% in the placebo group (n = 63) and 94.0% in the vitamin D group (n = 67).

Roth et al.

Roth et al. Nutrition Journal 2013 12:47   doi:10.1186/1475-2891-12-47

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