Table 4. Comparison of frequency of medication overuse headache between aged (≥65) onset group and younger age onset (<65) group.

	Age <65 Ncase/Ntotal (%)	Age ≥65 Ncase/Ntotal (%)	p value*
Migraine	52/680 (7.6)	4/17 (23.5)	0.040
Tension-type headache	11/375 (2.9)	4/70 (5.7)	0.271
Other primary headache disorders	1/226 (0.4)	0/39 (0.0)	Not available

Values are number of case/total number of each headache (%).

^*p value were acquired by Fisher's exact test according to each headaches.