. 2018 Sep 1;10(9):1197. doi: 10.3390/nu10091197

Table 3.

Association between plasma 25-hydroxy vitamin D and school performance before and after adjusting for potential confounders (Median Regression).

Vitamin D Status	Model 1	Model 2	Model 3	Model 4	Model 5
Vitamin D Status	β [95%CI]	β [95%CI]	β [95%CI]	β [95%CI]	β [95%CI]
25-OH-D levels nmol/L	0.02	−0.00	−0.00	−0.01	−0.01
25-OH-D levels nmol/L	[−0.01, 0.06]	[−0.03, 0.03]	[−0.04, 0.03]	[−0.04, 0.03]	[−0.04, 0.03]
p-value	0.22	0.94	0.77	0.67	0.69
Q1 (25-OH-D < 19.2 nmol/L) (n = 337)	[Reference]	[Reference]	[Reference]	[Reference]	[Reference]
Q2 (25-OH-D ≥19.2 to <29.7 nmol/L) (n = 346)	1.10	1.61	2.01	1.66	1.74
Q2 (25-OH-D ≥19.2 to <29.7 nmol/L) (n = 346)	[−1.54, 3.74]	[−0.34, 3.57]	[0.01, 4.01]	[−0.42, 3.75]	[−0.33, 3.80]
Q3 (25-OH-D from 29.7 to <44.1 nmol/L) (n = 344)	0.40	0.70	0.98	0.90	0.94
Q3 (25-OH-D from 29.7 to <44.1 nmol/L) (n = 344)	[−2.15, 2.95]	[−1.58, 2.99]	[−1.26, 3.21]	[−1.39, 3.20]	[−1.41, 3.30]
Q4 (25-OH-D ≥ 44.1 nmol/L) (n = 343)	2.60	0.82	1.00	1.40	1.67
Q4 (25-OH-D ≥ 44.1 nmol/L) (n = 343)	[0.06, 5.25]	[−1.51, 3.14]	[−1.38, 3.38]	[−1.03, 3.83]	[−0.86, 4.19]
p-value	0.17	0.43	0.27	0.45	0.36
Severe deficiency (25-OH-D < 25 nmol/L) (n = 544)	[Reference]	[Reference]	[Reference]	[Reference]	[Reference]
Deficiency (25-OH-D ≥ 25 to <50 nmol/L) (n = 572)	−0.30	−1.36	−0.84	−0.99	−0.94
Deficiency (25-OH-D ≥ 25 to <50 nmol/L) (n = 572)	[−2.35, 1.75]	[−3.04, 0.32]	[−2.65, 0.96]	[−2.73, 0.73]	[−2.88, 0.99]
Insufficiency (25-OH-D ≥ 50 to <75 nmol/L) (n = 205)	2.30	−0.34	0.31	0.28	0.38
Insufficiency (25-OH-D ≥ 50 to <75 nmol/L) (n = 205)	[−0.33, 4.93]	[−2.46, 1.77]	[−2.51, 1.88]	[−1.89, 2.47]	[−1.97, 2.73]
Sufficiency (25-OH-D ≥ 75 nmol/L) (n = 49)	3.10	−1.71	−1.27	−2.12	−1.99
Sufficiency (25-OH-D ≥ 75 nmol/L) (n = 49)	[−0.83, 7.03]	[−5.15, 1.73]	[−5.39, 2.84]	[−5.99, 1.74]	[−5.86, 1.89]
p-value	0.08	0.38	0.78	0.35	0.45

Q1 to Q4: quartile one to quartile four; Model 1: unadjusted; Model 2: adjusted for socio-demographic factors (age, gender, nationality, season of birth, governorate, education of the father, education of the mother, total number of siblings, father income, employment of the mother, type of housing, and child birth order), passive smoking at home, frequency of having breakfast before going to school, and frequency in addition to the number of times the child had breakfast or dinner prepared outside their home; Model 3: adjusted for variables in Model 2 in addition to sleeping hours during weekends having nap during weekend, time of the first meal during weekend and weekdays, and frequency of sugary drinks; Model 4: adjusted for variables in Model 3 in addition to BMI categories; Model 5: adjusted for variables in Model 4 in addition to parathyroid hormone.