Table 1.

Sociodemographic characteristics of patients with chronic migraine (CM) and the two comparison groups

	CM cases (N = 681)		Comparison cohort: cases with other migraine (N = 2,226)		P value	CM cases (N = 948)		Comparison cohort: non-migraine population (N = 3,790)		P value
	n	%	n	%		n	%	n	%
Age (years)
<20	40	5.87	102	4.58	0.348	70	7.38	280	7.39	1.000
20–40	273	40.09	941	42.27		382	40.30	1,526	40.26
40–60	292	42.88	964	43.31		356	37.55	1,424	37.57
≥60	76	11.16	219	9.84		140	14.77	560	14.78
Gender
Male	146	21.44	446	20.04	0.426	234	24.68	934	24.64	0.980
Female	535	78.56	1,780	79.96		714	75.32	2,856	75.36
Urbanization level
1 (high)	259	38.03	934	41.96	0.101	282	29.75	1,128	29.76	1.000
2	229	33.63	768	34.50		305	32.17	1,220	32.19
3	82	12.04	252	11.32		151	15.93	604	15.94
4–5	70	10.28	187	8.40		109	11.50	436	11.50
6–7	35	5.14	79	3.55		100	10.55	400	10.55
Missing	6	0.88	6	0.27		1	0.11	2	0.05
Premiums (NT$)
>43,900	79	11.60	242	10.87	0.722	103	10.86	412	10.87	1.000
30,301–43,900	55	8.08	187	8.40		81	8.54	324	8.55
21,001–30,300	74	10.87	274	12.31		105	11.08	420	11.08
≤21,000	67	9.84	241	10.83		98	10.34	392	10.34
Fixed	406	59.62	1,282	57.59		561	59.18	2,242	59.16

RR relative risk, CI confidence interval, SD standard deviation