Serum vitamin D level and its association with anti-seizure medications in children with seizure disorder

Table 1 Baseline characteristics of the included children (n = 150)

Characteristics	n (%)
Age sub-groups
1-5 years	67 (44.7)
> 5 years	83 (55.3)
Gender
Male	97 (64.7)
Female	53 (35.3)
Birth asphyxia	28 (18.7)
Developmental delay	19 (12.7)
Severe malnutrition	8 (5.3)
Rural residence	84 (56)
Low socioeconomic status	51 (34)

Table 2 Details regarding seizure, antiseizure medication, and baseline vitamin D level

Characteristics	Values [mean ± SD or median (IQR)]	Values, n (%)
Age at onset of seizure (year)	6.5 ± 3.9	-
Duration of seizure prior to start of ASM (month)	1 (0-6)	-
Duration of ASM (month)	4.3 ± 1.1	-
Baseline vitamin D [25(OH)D] level (ng/mL) in different treatment groups
Monotherapy	21.84 ± 10.1	61 (40.7)
Polytherapy	20.12 ± 9.3	89 (59.3)
Enzyme-inducing ASM1	19.97 ± 9.6	62 (41.3)
Non-enzyme-inducing ASM2	21.15 ± 9.8	88 (58.7)

¹Phenytoin, phenobarbitone, carbamazepine, and oxcarbazepine.

²Sodium valproate, levetiracetam, and benzodiazepines.

ASM: Antiseizure medication; IQR: Inter-quartile range; [25(OH)D]: 25-hydroxyvitamin D.

Table 3 Association of serum vitamin D categories with seizure control

Vitamin D category	Controlled, n (%)	Uncontrolled, n (%)	Total, n	P value
Sufficient (≥ 30 ng/mL)	29 (53.7)	25 (46.3)	54
Insufficient (20-29 ng/mL)	28 (41.8)	39 (58.2)	67
Deficient (< 20 ng/mL)	8 (27.6)	21 (72.4)	29
Total	65	85	150	0.08a

^aP > 0.05.

Table 4 Serum vitamin D level at baseline, and follow-up (6 months and 18 months)

Time points of measurement	Vitamin D level (ng/mL)		P value
	mean ± SD	Range
Baseline	21.33 ± 9.6	10.6-40.24
6 months	19.75 ± 8.9	10.2-38.65
18 months	18.61 ± 8.7	8.3-30.1	0.651

¹Comparison performed using repeated measures analysis (Analysis of Variance); differences were not statistically significant.

Table 5 Multivariable logistic regression analysis showing association of low vitamin D status with clinical characteristics antiseizure medication therapy and seizure control

Variables	Adjusted OR (95%CI)	P value
Gender
Male	0.72 (0.34-1.51)	0.38
Female	1.0
Age group
1-5 years	1.03 (0.52-2.04)	0.93
> 5 years	1.0
ASM therapy
Monotherapy	0.68 (0.33-1.39)	0.29
Polytherapy	1.0
Seizure control
Controlled	0.55 (0.27-1.12)	0.09
Uncontrolled	1.0

OR: Odds ratio; CI: Confidence interval; ASM: Antiseizure medication.

Table 6 Multivariable linear regression analysis of factors associated with serum vitamin D levels

Variables	β coefficient	Standardized β (β1)	95%CI	P value
Age (years)	-0.05	-0.06	-0.2 to 0.1	0.52
Male sex	0.3	0.08	-0.8 to 1.4	0.59
Malnutrition	-1.1	-0.14	-2.8 to 0.6	0.20
Developmental delay	-0.9	-0.12	-2.5 to 0.7	0.26
Low socioeconomic status	-0.7	-0.09	-2.1 to 0.7	0.32
Enzyme-inducing ASM	-0.8	-0.11	-2.0 to 0.4	0.19
Duration of ASM (months)	-0.12	-0.13	-0.3 to 0.06	0.18

β: Unstandardized regression coefficient; β1: Standardized regression coefficient; CI: Confidence interval; ASM: Antiseizure medication.