Table 4.

Means of each variable among clusters

Hierarchical clustering using Ward method
	Total	Cluster 1	Cluster 2	Cluster 3	Kruskal–Wallis test or Chi-squared test	Mann–Whitney U test or Chi-squared test
Number	136	25	83	28
Age (y.o.)	42.49	23.8	46.3	47.89	< 0.001***	1 < 3,2; p < 0.001 all***
Sex: Women is 1	0.80	0.80	0.80	0.84	0.867	-
Headache frequency†	0.81	0.84	0.23	2.50	< 0.001***	1,2 < 3; p < 0.001 all***
Migraine is 1	0.19	0.17	0.17	0.28	0.137	-
Duration‡	2.62	2.48	2.52	3.04	0.256	-
Use of combination-analgesic is 1	0.67	0.57	0.72	0.68	0.043	p > 0.050 all
Frequency of acute medication oral intake (days/months)	17.08	15.36	13.53	29.14	< 0.001***	2,1 < 3; p < 0.001 all***
Use of prophylactic medication is 1	0.07	0.11	0.06	0.040	0.272	-
Non-hierarchical clustering using k-means +  +
	Total	Cluster 1	Cluster 2	Cluster 3	Kruskal–Wallis test or Chi-squared test	Mann–Whitney U test or Chi-squared test
Number	136	25	65	46
Age (y.o.)	42.49	23.80	41.31	54.33	< 0.001***	1 < 2 < 3; p < 0.001 all***
Sex: Women is 1	0.80	0.84	0.80	0.80	0.907	-
Headache frequency†	0.81	0.84	0.54	1.17	0.055	-
Migraine is 1	0.19	0.28	0.17	0.17	0.457	-
Duration‡	2.62	2.48	2.62	2.70	0.827	-
Use of combination-analgesic is 1	0.67	0.68	0.72	0.57	0.218	-
Frequency of acute medication oral intake (days/months)	17.08	15.36	15.74	19.91	< 0.001***	1,2 < 3; p = 0.021 for 1 vs 3* p = 0.005 for 2 vs 3**
Use of prophylactic medication is 1	0.07	0.04	0.06	0.11	0.500	-

*; p < 0.050, **; p < 0.010 ***; p < 0.001, †; Ordinal scale for headache frequency as follows. 0; 15–19 days/months, 1; 20–24 days/months, 2; 25–29 days/months, 3; everyday, ‡; Ordinal scale for headache duration as follows. 0; less than 60 min, 1; 1–3 h; 2; 4–8 h, 3; 9–24 h, 4; 2–3 days, 5; 4–7 days, 6; over 8 days