Table 2.

Vitamin D levels and clinical and MRI activity during the study

	Baseline n=469	Year 1 n=447	Year 2 n=407	Year 3 n=353	Year 4 n=345	Year 5 n=350
25-hydroxyvitamin level (ng/mL) at prior visit, mean ± SD	N/A	27.8 ± 10.7	27.8 ± 10.9	27.7 ± 11.5	30.7 ± 12.8	32.9 ± 15.8
EDSS score, median (IQR)	1.5 (0, 5)	2 (0, 6.5)	2 (0, 6)	2 (0, 6)	2 (0, 6.5)	2 (0, 6)
Relapses since prior visit, median (IQR)*[mean ± SD]	0 (0, 4) [0.6 ± 0.8]	0 (0, 3) [0.3 ± 0.7]	0 (0, 2) [0.3 ± 0.6]	0 (0, 2) [0.2 ± 0.5]	0 (0, 2) [0.2 ± 0.5]	0 (0, 2) [0.1 ± 0.4]
New T2 lesions since last scan, median (IQR)[mean ± SD]	N/A	0 (0, 24) [1.8 ± 5.0]	1 (0, 16) [1.9 ± 3.8]	0 (0, 4) [0.2 ± 0.7]	0 (0, 4) [0.2 ± 0.7]	0 (0, 5) [0.3 ± 1.0]
Gadolinium-enhancing lesions, median (IQR)[mean ± SD]	0 (0,6) [0.3 ± 1.0]	0 (0, 8) [0.3 ± 1.3]	0 (0, 3) [0.1 ± 0.6]	0 (0, 2) [0.1 ± 0.8]	0 (0, 1) [0.0 ± 0.3]	0 (0, 1) [0.0 ± 0.2]

EDSS= Expanded Disability Status Scale; IQR= interquartile range; SD= standard deviation

Lesion counts do not account for the fact that some patients had missed visits, so the summary statistics may reflect activity over more than one year. In the statistical models, this concern is addressed by using an offset of the log time since the prior visit/scan. Vitamin D levels from the prior year were missing for one patient at year 1, two patients at year 3, and six patients at year 5. EDSS scores were missing for 2 subjects at year 1, 2, and 4, and for 3 subjects at year 3 and 5). Gadolinium-enhancing lesions could not be determined for one patient at baseline. In follow-up, of those for whom vitamin D levels were available, seven patients missed a brain MRI (at one time point each); 23 subjects were missing either gadolinium-enhancing lesion or new T2 lesion counts at one time point, while three patients were missing one of the measures at two time points.

^*For the baseline visit, the number of relapses in the year prior to the visit was documented.