Review: antidepressants improve headache in patients with chronic headache.

Data extraction Data were extracted on setting, country of origin, patient inclusion and exclusion criteria, sample size, demographical characteristics, comorbid psychiatric disease, concurrent use of analgesic medications, key components of the intervention, study quality, adverse effects, and outcomes. Outcomes were overall improvement in headache ( > 50% reduction in Headache Index scores, global improvement based on > 50% improvement, impression of improvement, or headache frequency or severity) and effect size of treatment (measured in standard deviation units) on headache burden.