Chronic antiepileptic drug use and functional network efficiency: A functional magnetic resonance imaging study

Table 1 Patient characteristics for the three risk categories¹

	Low risk (n = 16)	Intermediate risk (n = 34)	High risk (n = 5)
General
Male/female	5/11 (31%/69%)	16/18 (47%/53%)	0/5 (0%/100%)
Age (yr)2	39.5 ± 13.4	50.7 ± 12.5a	42.4 ± 15.8
Educational level3	5 (range 2-6)	5 (range 2-7)	5 (range 4-6)
Epilepsy-related
Symptomatic/non-symptomatic epilepsy	2/14 (13/88%)	15/19 (44/56%)	0/5
Seizure frequency
Weekly	0	1 (3%)	0
Monthly	4 (25%)	3 (9%)	0
Yearly	2 (13%)	6 (18%)	2 (40%)
Seizure free	10 (63%)	24 (71%)	3 (60%)
Years since epilepsy onset2	22.7 ± 11.7	30.4 ± 13.4	26.8 ± 23.3
Epilepsy severity score2	1.4 ± 0.8	1.2 ± 1.0	1.0 ± 0.7
AED-related
Mono-/polytherapy	16/0	8/26 (24/77%)a	3/2 (60/40%)b
Medication type
CBZ	0	17 (50%)	1 (20%)
LEV	7 (44%)	6 (18%)	0
LTG	9 (56%)	10 (29%)	1 (20%)
OXC	0	4 (12%)	0
PHT	0	16 (47%)	0
TPM	0	0	5 (100%)
VPA	0	7 (21%)	1 (20%)
Drug load2,4	1.3 ± 0.6	1.8 ± 0.7a	1.2 ± 1.0

Differences between the risk groups were tested using a Fisher’s exact test (gender, symptomatic epilepsy, number of different AEDs), a Mann-Whitney test (educational level, seizure frequency, epilepsy severity score), or a student’s t test (all remaining variables).

^aIndicates significant differences between the low and intermediate risk category (P < 0.05);

^bIndicates differences between the low and high risk category (P < 0.05). ¹Low risk: Lamotrigine (LTG), levetiracetam (LEV); Intermediate risk: Valproate (VPA), carbamazepine (CBZ), oxcarbazepine (OXC) and phenytoin (PHT); High risk: Topiramate (TPM);

²Mean ± SD;

³Median (range). Scores are according to Verhage[30], range 1 (did not finish primary school) to 7 (Master’s degree);

⁴The drug load is defined as the ratio of the prescribed daily dose to the defined daily dose[29]. AED: Antiepileptic drug.

Table 2 Results of the neuropsychological investigation, represented as mean ± SD for each risk category

	Cognitive test results
	CVST (s)1	Raven2
Risk category
Low risk	11.5 ± 2.9	71.7% ± 10.3%
Intermediate risk	15.7 ± 6.4	73.2% ± 10.1%
High risk	20.2 ± 6.7	71.7% ± 3.1%
P value3	0.008	0.85

¹Mean reaction time on the Computerized Visual Searching Task (CVST)[22];

²Percentage correct answers on the Raven Standard Progressive Matrices[24];

³Tested with ANOVA.