ORIGINAL ARTICLE

Epidemiology and clinical characteristics of chronic dailyheadache in a clinic-based cohort of Iranian population

Seyed Mohammad Seyed Saadat • Mozaffar Hosseininezhad •

Babak Bakhshayesh • Mahsa Hoseini •

Mohamadreza Naghipour

Received: 8 June 2013 / Accepted: 12 September 2013

� Springer-Verlag Italia 2013

Abstract 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 pre-

senting 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 his-

tory, 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.

Keywords Chronic daily headache �Chronic tension-type headache � Migraine disorders �Tertiary care centers � Outpatient clinics � Iran

Abbreviations

CDH Chronic daily headache

CM Chronic migraine

CTTH Chronic tension-type headache

HC Hemicrania continua

NDPH New daily persistent headache

MOH Medication overuse headache

CH Cervicogenic headaches

ICHD International Classification of Headache

Disorders

Introduction

Chronic daily headache (CDH) is defined as a headache

that occurs on at least 15 days per month, for at least

3 months, and can be divided into primary and secondary

types [1–3]. Although CDH is a major health care problem

encountered in headache clinics, few studies have been

conducted regarding the epidemiological features of CDH

in developing countries, particularly in the Middle East and

Iran [4, 5], where environmental exposures, socioeconomic

condition, genetic background, availability of medical

services, trends in self-drug consumption, and geographic

S. M. Seyed Saadat � M. Hoseini

Medical Student Research Committee, Guilan University of

Medical Sciences, Rasht, Iran

M. Hosseininezhad � B. Bakhshayesh (&)

Department of Neurology, Poursina Hospital, Guilan University

of Medical Sciences, 41486-48476 Rasht, Iran

e-mail: babak.bakh@gmail.com

M. Naghipour

Department of Social Medicine, Faculty of Medicine, Guilan

University of Medical Sciences, Rasht, Iran

123

Neurol Sci

DOI 10.1007/s10072-013-1550-2

characteristics are different. In the only population-based

study performed in Tehran, the capital of Iran and one of

the biggest cities in the Middle East [5], the prevalence of

CDH (7 %) among Iranian population was higher than

reported rates in most previous studies [6–9], and the

highest ever-reported prevalence rate of MOH (4.9 %) was

found among adult individuals of Tehran.

Considering that most previous studies were conducted

based on the old version of the CDH criteria [1], and given

that no clinic-based study have been performed on CDH

among Iranian population so far, therefore, we performed

this prospective study to survey the relative frequency of

CDH and its subtypes among Iranian patients attending to a

referral tertiary headache clinic in Rasht, the Capital city of

Guilan Province, northern Iran.

Materials and methods

This cross-sectional clinic-based study was performed in

the Headache outpatient Clinic of the Neurology Depart-

ment of Poursina University–Hospital in Rasht, which is

the main referral tertiary clinic in the province, from

September 2011 to March 2012. All patients attending to

our Headache Clinic for their first visit, with a chief

complaint of headache presented 15 days or more per

month in at least three consecutive months were recruited.

The study was approved by the Human Research Com-

mittee at the Guilan University of Medical Sciences

(GUMS). Our clinic patients mostly come from primary or

secondary care centers or refer from private centers or

offices. The purpose of the study was explained to all

participants, and written informed consent was obtained.

Patients with clinical presentation of CDH were further

evaluated to identify the specific causes of headache

according to the second edition of the 2004 International

Classification of Headache Disorders (ICHD-II) diagnostic

criteria [10].

Patients underwent structured face-to-face interview and

asked for baseline information including age, sex, educa-

tional level, marital status and a history of analgesic use or

overuse. Detailed history and complete general and neu-

rological examinations were carried out by two attending

neurologists. Routine laboratory tests as well as Brain CT

scan/MRI were performed where necessary. The body

mass index (BMI) of each patient was calculated. Data of

each patient were finally recorded in a questionnaire.

Further work-up using specific diagnostic laboratory tests

procedures or imaging tools (i.e., lumbar puncture, nerve

block, sinus radiographs, etc.) was attempted to rule out the

secondary causes in patients who presented with warning

signs and symptoms which were not consistent with the

diagnosis of primary headaches [3, 11, 12].

In patients with definite CDH, subtypes of CDH were

determined based on the ICHD-II. CDH was divided into

three main categorization including CM, CTTH and other

causes of primary CDH. Patients who did not meet the

criteria of ICHD-II were considered as ‘‘other CDH’’. We

considered secondary CDH as the main diagnosis if it was

accompanied by another subtype of CDH. We followed up

patients 2 months later using telephone call to confirm the

final diagnosis. The diagnosis of MOH was made accord-

ing to the revised ICHD-II criteria for 8.2 Medication

overuse headaches [13]. The diagnosis of MOH was ruled

out in patients whose headache was not resolved after

discontinuation of the overused or abused medication for a

period of 2 months. In those cases, the diagnosis of other

subtypes of headache syndrome was established based on

the ICHD-II classification.

Statistical analysis

The study data were analyzed using SPSS software. All

variables were normally distributed according to the Kol-

mogorov–Smirnov test. Descriptive data were reported

using mean ± SD and percentage. Due to normal distri-

butions, the parametric tests were used in the analyses. We

used test and one-way ANOVA to compare demographic

and clinical characteristics between different subgroups of

headache in this study. One-way ANOVA with post-hoc

Tukey test was performed to compare mean age between

different subtypes of CDH. P value B0.05 was considered

statistically significant.

Results

Of the 541 cases admitted to our headache clinic, 177 cases

(32.71 %) fulfilled the CDH criteria. Among 177 patients

with CDH, eight patients (4.5 %) with red flag signs and

symptoms were excluded from our study, because they did

not consent to undergo MRI/CT examination (n = 4),

nerve block procedures (n = 2), LP (n = 1), or temporal

artery biopsy (n = 1). After diagnostic work-up, 17

patients were lost to follow-up at 2 months, but included in

the final analysis based on their initial probable diagnosis.

Eventually, 169 patients were included in our study

(Fig. 1).

The prevalence of CDH was considerably higher in

female (68 %), with a female to male ratio of 2.12/1. The

mean age of patients was 38.25 ± 13.23 ranged from 11 to

76 years and the highest frequency of CDH was found in

the 40–49 age groups (n = 54). The mean age of male and

female patients with CDH was 37.96 ± 13.28 and

38.39 ± 13.26 years, respectively (P = 0.58). Thirty-six

subjects (21.3 %) were divorced, widowed or separated.

Neurol Sci

123

The majority of cases (49.1 %) were overweighed, and

only 29 subjects (17.2 %) had academic education or col-

lege degree (Table 1).

The frequency and demographic characteristic of dif-

ferent subtypes of CDH is shown in Table 1. CM (44.4 %)

and CTTH (27.8 %) were the most prevalent types of CDH

in our population. Other primary CDH accounted for 7.7 %

of all cases. The frequency of other prevalent CDHs were

as follow: new daily persistent headache (NDPH) (5.3 %),

cluster headache (1.2 %), hemicrania continua and one

multiple sclerosis patient with idiopathic nummular head-

ache (IHS code 14.1) (0.6 %). Of the total cases, 20.1 %

suffered from secondary headaches. Cervicogenic head-

aches (10.7 %) and medication overuse headache (MOH)

(4.1 %) were the most common causes of secondary

headaches. Other causes of secondary headaches were

temporal arteritis (1.2 %), headaches arising from sinus

disorders (1.2 %), intracranial mass (1.2 %), idiopathic

intracranial hypertension (0.6 %), previous head trauma

(0.6 %), and trigeminal neuralgia (0.6 %).

Patients who suffered from chronic migraine had a mean

age of 33.17 ± 12.5 years. The mean ages of patients with

CTTH, and secondary headaches were 39.19 ± 13.41 and

46.35 ± 11.22, respectively. One-way ANOVA showed a

significant difference in the average age of patients with

different subtypes of CDH (P \ 0.001). Post-hoc Tukey

analysis subsequently confirmed that patients with CM

were significantly younger than patients with secondary

CDH (P \ 0.001). The prevalence of different types of

CDH according to age groups and gender is illustrated in

Fig. 2 and summarized in Table 1. This shows a higher

total frequency of CDH subtypes among women compared

with men in all age groups except for MOH, which was

more common in men than women (4 vs. 3 patients).

In contrast to the frequency of CM which gradually

declined over time, the incidence of secondary CDHs

dramatically increased after the fifth decade of life

(P = 0.004) (Fig. 3). Although different subtypes of CDH

were not statistically associated with gender (P = 0.309),

BMI (P = 0.711), and educational level (P = 0.326), there

was a significant association between CDH subtypes and

the marital status (P = 0.015), as the relative frequency of

CM in single individuals (65.9 %) was higher than married

(41.3 %, P = 0.014) and divorced/widowed or separated

individuals (27.8 %, P = 0.001).

Follow-up

Of the 17 patients who were lost to follow-up at 2 months,

the picture at best was compatible with the initial diagnosis

of CM and CTTH in 11 and 6 patients, respectively. In 7

patients out of 16 cases with probable MOH, daily head-

ache was resolved 2 months after discontinuation of the

overused drug. These patients were classified as having

definite MOH. Of the remaining nine patients, eight

patients had CM and the other one had CTTH.

Discussion

Consistent with the previous clinic-based surveys [4, 14], a

considerable proportion of patients, about one-third,

attended to our Headache clinic were diagnosed to have

CDH. CDH was most commonly found in women aged

30–39 years. This finding is important as headache-related

disability can not only result in remarkable damages to the

patients, but also costs economically a lot to the society by

affecting the economically most active working population

[15].

The findings of the current study demonstrated that

CDH is more frequent in women with a female to male

ratio of 2.12/1. The female to male ratio of CDH was 5.6/

1.8 in Chinese population older than 65 years [16], and 2.4

to 1 in Brazil [17]. The average age of CDH patients in our

study was 38.25 years, which was higher than some pre-

vious studies [4, 14]. Causes of CDH vary among different

studies [7]. Consistent with findings of previous studies [6,

14], the prevalence of CM was higher than other subtypes

of CDH, while it was lower than that of Thailand [4] and

Fig. 1 Flow diagram

Neurol Sci

123

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Neurol Sci

123

elderly population of China [16], where CTTH was the

most common. A possible reason for this difference is

attributed to the study population. Since CM is accompa-

nied by higher intensity than other subtypes of CDH, it is

expected that patients with CM are more likely to seek for

medical care [15].

In our study there was no association between sex and

types of CDH. Although CM tended to occur more fre-

quently in women than CCTH [7], Both CM and CTTH

were more prevalent in our females’ cases. The distribution

of the CDH subtypes was different among our population

according to their age groups. In patients younger than

50 years, CM remained the most common cause of CDH.

Secondary causes of headaches were the common causes in

females older than 50 years. This pattern of distribution

was seen more predominantly in our female cases in their

6th decades of life or above. While no such a relationship

was seen among different age groups of male cases. In

accordance with the results of prior studies, most of our

patients who diagnosed to have CM and CTTM were in

their 4th decade of life [2, 18].

Secondary headaches caused one-fifth of all CDHs in

our study. Although MOH was the most common subtype

of secondary CDH in most previous studies [7, 14, 19],

cervicogenic (52.9 %) formed the most prevalent cause of

headache among our patients who diagnosed to have

secondary CDH. Moreover, MOH constituted 4 % of all

causes of CDH, which was less than our expectation.

However, this finding does not support the previous study

by Pascual et al. [14], who reported an 80 % prevalence of

analgesic overuse among individuals with CDH, and is in

contrary with results of a population-based study by Ca-

stillo who showed that 31 % of cases with CDH overuse

painkillers [19]. A possible explanation for this contra-

dictory result could be attributed to the use of different

diagnostic criteria for the definitions of MOH in prior

studies, resulted in substantial diversity in the reported

incidence and prevalence rates of MOH among studies. As

MOH was not considered as a single disorder in these

studies according to their used criteria; while, it is a

crucial criterion in the identification of CDH in new

revision of ICHD-II [4, 10, 13]. Cultural issues and a

lower tendency of patients to use medication for chronic

pain on their own in our area could explain other reasons

of such discrepancy. On the other hand, cervicogenic

headaches were responsible for 10.7 % of all causes of

CDH and 52.9 % of secondary causes in our study. This is

the highest ever-expressed frequency of CH compared

with previous similar studies [20–22], which reported the

prevalence of cervicogenic headaches ranged from 0.17 to

4.6 in different populations. This could be explained by

differences in designs and populations of studies, or use of

different diagnostic criteria, other than ICDH, in previous

studies [20]. Furthermore, new criteria do not have high

Fig. 2 Subtypes of CDH

stratified by age and gender.

Y number, X age (year)

Fig. 3 Frequencies of different subtypes of CDH according to the

age groups

Neurol Sci

123

specificity for the diagnosis of cervicogenic headaches, as

CM or CTTH may also respond to nerve block.

The current study had several limitations that should be

noted: (1) our study was conducted in a tertiary care center.

This could have resulted in selection bias of including only

severe cases in our study, and subsequently lead us to

overestimate the frequency of CDHs with higher severity

such as CM. As a result, we could not generalize our results

neither to the general population nor to primary care levels;

(2) as the data collection in our study was based on patient’s

self-reported information during face-to-face interview; the

analgesic overuse might not been reported properly by

individuals. Therefore, the rate of MOH in our study might

be underestimated; (3) as our Headache Clinic is a univer-

sity center that provides a cheaper service than private

centers; patients attending our center might have lower

socioeconomic status, which can influence the frequency of

CDH and its different subtypes among our study population.

Conclusion

In conclusion, CDH is among the leading causes of annual

visit to tertiary headache clinics, and CM remains as the

most common cause of CDH in both men and women

below 40 years of age. However, secondary causes should

always be considered, especially among women aged

above 40 years. Better understanding of the epidemiolog-

ical feature of CDHs helps general physicians and spe-

cialists of primary and secondary care settings to list

properly the differential diagnosis of chronic headaches

and choose the most effective treatment approach.

Acknowledgments We are grateful to all the patients for their

participation in the study. This work was financially supported by

grants from the Guilan University of Medical Sciences.

Conflict of interest The authors declare that there is no conflict of

interest.

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