Table 1.

Clinical and demographic characteristics of healthy controls (HC), episodic migraine (EM), and chronic migraine (CM).

	HC (n = 50)	EM (n = 51)	CM (n = 56)	Statistical test
Gender, male/female	11/39	7/44	6/50	${\chi }_{(2,N=157)}^2$ = 2.74
Age (years)	36.1 ± 13.2	36.6 ± 7.9	38.1 ± 8.7	${\chi }_{(2)}^2$ = 2.79, p = 0.25‡
Duration of migraine history (years)		13.1 ± 10.5	19.6 ± 10.4	U = 932.5, p = 0.002◇
Time from onset of chronic migraine (months)			24.5 ± 32.9
Headache frequency (days/month)		3.6 ± 1.9	23.3 ± 6.3	U = 40.0, p < 0.001◇
Migraine frequency (days/month)		3.6 ± 1.9	13.9 ± 6.9	U = 99.5, p < 0.001◇
Medication overuse		0 (0%)	42 (75%)	p < 0.001*
Aura		9 (18%)	1 (2%)	p = 0.006*

^†Chi-square test. ^‡Kruskal-Wallis test. ^◇Mann-Whitney U-test. ^*Fisher's exact test. Data are expressed as means ± SD.