Impact of oral dexamethasone versus placebo after ED treatment of migraine with phenothiazines on the rate of recurrent headache: a randomised controlled trial

OBJECTIVE: Evidence suggests that the rate of recurrent headache after treatment of migraine in the emergency department (ED) is high. The mechanisms for this are unclear, but neurogenic inflammation may play a role. There is conflicting evidence about whether adjuvant dexamethasone reduces the rate of recurrent headache. The aim of this study was to compare the rate of recurrent headache in patients with migraine randomised to receive a single dose of oral dexamethasone or placebo at discharge after treatment in the ED with intravenous phenothiazine. <br /><br />METHODS: A double-blind, randomised, placebo-controlled trial was conducted in the ED of three community teaching hospitals. Adult patients with physician-diagnosed migraine were treated with intravenous phenothiazine and at discharge were randomised to receive either 8 mg oral dexamethasone or placebo as a single dose. Follow-up was by telephone at 48-72 h and the proportion of patients with recurrent headache overall and in the subgroup with headache duration <24 h was recorded. <br /><br />RESULTS: 63 patients (76% women) of median age 39 years were enrolled, 61 of whom (97%) completed follow-up. The pooled rate of recurrent headache was 33%. 32 were randomised to placebo and 31 to dexamethasone. The rate of recurrent headache in the dexamethasone and control groups was 27% (8/30) vs 39% (12/31) (relative risk (RR) 0.69, 95% CI 0.33 to 1.45, p = 0.47). For 40 patients with headache lasting <24 h the rate of recurrent headache in the dexamethasone and control groups was 15% (3/20) vs 45% (9/20), a reduction in absolute risk of 30% (RR 0.33, 95% CI 0.11 to 1.05, p = 0.08). <br /><br />CONCLUSION: A single oral dose of dexamethasone following phenothiazine treatment for migraine in the ED did not reduce the rate of recurrent headache. There is weak evidence for a possible benefit in the subgroup who present within <24 h of symptom onset. A multicentre trial to confirm this finding is warranted.