Epidemiology of tension-type headache in Santiago, Chile: a prevalence study

Objective: To describe the importance of tension-type headache (TTH) in Santiago, Chile, by analyzing its prevalence, clinical features, and impact by age, gender, and socioeconomic status, using widely accepted international diagnostic criteria. Methods: In 1993, a representative sample of 1540 adults (older than 14) of the province of Santiago were interviewed using a standard questionnaire. A total of 1385 (89.9% response rate) subjects responded to the survey. Initially, a designated member of each household responded to the questionnaire. Subsequently, each household member with headache was asked to respond to questions about the severity, frequency, location, duration, associated symptoms, and impact in work and social activities of their most frequent headaches. TTH diagnoses were determined in accordance with the International Headache Society criteria of 1988. Results: Total prevalence was found to be 26.9% (95% CI: 24.6-29.3%); 35.2% in females (95% CI: 31.7-38.8%) and 18.1% in males (95% CI: 15.2-21.3%). The prevalence of episodic TTH was 24.3% (95% CI: 22.1-26.7%) and of chronic TTH: 2.6% (95% CI: 1.8-3.6%). Overall, and by subtype, prevalence was significantly higher in females (ratio 1:9). There was no significant variation in prevalence by socioeconomic or age group except in chronic TTH, in which there was an increase with age. Conclusions: TTH is a prevalent condition in a sample of adults of Santiago, similar to that reported in previous studies using similar methodologies. Overall, TTH represents 72.3% of all recent headaches.