Epidemiology and clinical characteristics of chronic daily headache in a clinic-based cohort of Iranian population.

Although CDH is a major health care problem encountered in headache clinics, our knowledge about the epidemiological features of CDH is limited in developing countries. The objective of this study was to survey the frequency and clinical features of chronic daily headache (CDH) and its subtypes among Iranian population presenting to a referral tertiary Headache clinic in a University Hospital. This cross-sectional survey was carried out between September 2011 and March 2012. Data of patients with CDH including their age, sex, educational level, and marital status were recorded using structured face-to-face interview. Subtypes of the CDH were determined by history, physical examination and appropriated laboratory or imaging findings. A total number of 177 cases (32.71%) fulfilled the CDH criteria. The frequency of CDH was higher in 40-49 age groups (n = 54) and among women with a female to male ratio of 2.12/1. Chronic migraine was the most common subtype of CDH in 75 cases (44.4%). Chronic tension-type headache and secondary causes were second and third frequent subtypes of CDH in 27.8 and 20.1% of cases, respectively. Cervicogenic headaches (10.7%) and medication overuse headache (4.1%) were the most common causes of secondary headaches. The present study confirmed previous findings which showed a high prevalence of CDH and chronic migraine in clinic setting, with preponderance for women. In addition, we found the highest prevalence of cervicogenic headaches among secondary causes of CDH.