The outcomes and predictors of chronic daily headache (CDH) were determined in a 2-year longitudinal study of a sample of 122 adolescents (32 male/90 female; ages 12-14) with annual telephone follow-up by neurologists at Taipei Veterans General Hospital, Taiwan. Response rates were 92% in 2001 and 84% in 2002. Average monthly headache frequency was 11.0 +/- 9.7 days in 2001 and 7.7 +/- 6.5 days in 2002. Persistence rates of CDH were 40% in 2001 and 25% in 2002. Medication overuse was 20% at baseline and 6% at 2 years. Based on the International Classification of Headache Disorders-2nded 2004 (ICHD-2), the prevalence of migraine was not significantly changed during follow-up (67% at baseline and 60% at 2 years), whereas tension-type headache (CTTH) decreased from 86% to 46% in the same time interval (P<0.001). When using ICHD-2 appendix criteria (2006), chronic migraine prevalence increased 3 to 4 times when compared with the original ICDH-2 criteria. Chronic migraine became more common than CTTH in patients with persistent CDH in 2001 and 2002. Headaches adversely affected learning at school in 56% in 2001 and 57% in 2002; 7 (6%) dropped out of school during the 2-year follow-up. Poor outcome predictors included female gender, chronic migraine (by ICHD-2 appendix criteria), medication follow-up. Poor outcome predictors included female gender, chronic migraine (by ICHD-2 appendix criteria), medication overuse, major depression, anxiety disorders, school phobia, and OCD. Independent predictors for CDH persistence were medication overuse (P<0.05) and major depression (P<0.01). In contrast, migraine, age at CDH onset, and CDH duration were not significant predictors. 
COMMENT. Whereas the incidence of CDH in adolescents declines over a 2-year follow-up, the relative prevalence of migraine diagnosis increases when compared to chronic tension-type headache, especially when the ICHD-2 appendix criteria are employed. In a previous study of headache at the NIH among adolescent girls, the prevalence was 29.1% in grades 6 through 10. Heavy alcohol consumption, high caffeine intake, and cigarette smoking were strongly linked to somatic complaints associated with headache, including stomachache, back pain, and morning fatigue.