A cross-sectional study was conducted consecutively from March to May 2010 for headache among patients attending the neurological outpatient department at the First Affiliated Hospital of Chongqing Medical University. Each participant was interviewed by a qualified headache doctor and completed a self-administered questionnaire. Diagnosis was performed by doctors participating in the patient interviews and the diagnosis of CDH was confirmed by a headache specialist (corresponding author). The questionnaire was in three sections. The first included demographic details and past health status. The second comprised a headache profile, including duration of headache history (<1, 1–3, 4–6, >6 years), attack frequency (average number of headache days per month: <1, 2–4, 5–14, or ≥15 days/month) and severity using a 0–10 visual analog scale (VAS); pulsating, pressing/tightening or other headaches; presence or absence of headache aggravation from climbing stairs or routine physical activities; location (unilateral, bilateral or orbital), duration of headache attacks (<30min, 30 min to 2 h, 2–4 h, 4–72 h or >3 days) and accompanying symptoms (presence or absence of nausea, vomiting, photophobia or phonophobia, and clinical signs of cranial sympathetic dysfunction such as conjunctival injection, lacrimation, nasal congestion, rhinorrhoea, forehead and facial sweating, miosis, ptosis, eyelid edema). In addition, four major migraine aura symptoms (visual, sensory, motor and speech symptoms) were also queried. The third section concerned analgesic medication usage (never used, <1, 1, 2, ≥3 days/week), sleep status (excellent, good, fair, poor) and family history of headache.
] was applied to divide the patients into subgroups. Primary headache included migraine, TTH, cluster headache and other primary headaches [including primary stabbing headache, cough headache, hypnic headache, new daily persistent headache (NDPH) and others]. Secondary headache was diagnosed if the patient’s headache could be attributed to viral infection, cranial neuralgias, cranial or cervical vascular disorder, psychiatric disorder, sinusitis or alcohol ingestion. If the headache could not be accurately categorized as either primary or secondary, it was classified as headache not otherwise specified (headache NOS).
Patients who reported a headache frequency of at least 15 days/month over a period lasting more than 3 months were classified as having chronic daily headache (CDH). CDH included chronic migraine (CM), chronic tension-type headache (CTTH), medication-overuse headache (MOH), chronic cluster headache and NDPH. CM was defined by the following criteria revised by Olesen [9
]: (1) headache (tension type and/or migraine) on ≥15 days/month for at least 3 months; (2) migraine that fulfilled ICDH-II and was experienced on ≥8 days/month for at least 3 months; (3) no medication overuse.
For analysis, we defined the following two rules: (1) patients who fulfilled migraine diagnostic criteria, but also expressed other headache characteristics such as TTH, were categorized as having migraine; (2) probable migraine was also included with migraine. The study protocol was approved by the Ethical Committee at Chongqing Medical University and complied with the Declaration of Helsinki. All patients gave their informed consent for this study.
Statistical analysis of data was performed using the SPSS17.0 statistics package for PC. Demographic data were summarized using descriptive statistics. Quantitative data were presented as mean ± SD. The Student’s t test and the χ2 test were used for comparing quantitative and qualitative data, respectively. Separate variance estimation (t’ test) was used to detect possible differences in mean ages between primary headache and headache NOS, which had unequal variance. Mann–Whitney U tests were performed for ordinal categorical variables to identify the clinical features differing between migraine and TTH. All calculated p values were two tailed and statistical significance was defined as a p value of <0.05.