Recurrence of primary headache disorders after emergency department discharge: frequency and predictors of poor pain and functional outcomes.

STUDY OBJECTIVE: We determine the frequency of moderate or severe headache during the first 24 hours after an emergency department (ED) visit for a primary headache disorder (such as migraine or tension-type headache), determine the burden of headache during the 3 months after the ED visit, and identify predictors of poor pain and functional outcomes after ED discharge for each of these periods.

METHODS: In this prospective cohort study, we enrolled headache patients during their initial ED visit, interviewed them by using a standardized questionnaire, and followed them by telephone 24 hours and 3 months after ED discharge. Two emergency physicians classified all headaches according to criteria established by the International Headache Society, using a valid questionnaire and a reproducible technique.

RESULTS: During an 18-month period, we enrolled 309 primary headache disorder patients in the cohort. The most common primary headache diagnoses assigned to patients were migraine, tension-type headache, and unclassifiable recurrent headache disorder. We successfully obtained follow-up in 94% of patients 24 hours after ED discharge and in 94% 3 months after ED discharge. Moderate or severe headache was present within 24 hours of ED discharge in 31% (95% confidence interval [CI] 25% to 38%) of migraine patients, 19% (95% CI 9% to 36%) of tension-type headache patients, and 27% (95% CI 18% to 38%) of the unclassifiable headache patients. Multiple functionally impairing headaches occurred during the 3 months after ED discharge in 37% of migraine patients (95% CI 30% to 44%), 38% of tension-type headache patients (95% CI 23% to 54%), and 26% of the unclassifiable headache patients (95% CI 17% to 37). After multivariate adjustment, independent predictors of poor 24-hour outcomes were severe baseline pain, baseline nausea, screening positive for depression, and longer duration of headache; the independent predictor of poor 3-month outcomes was Medicaid insurance.

CONCLUSION: Regardless of type of primary headache disorder, ED headache patients frequently experience pain and functional impairment during the hours and months after discharge.