Seven RCTs (n=738) were included in the meta-analysis.
All the RCTs were of a relatively high quality, scoring between 4 and 5 points on the Jadad scale.
The addition of dexamethasone to standard abortive care significantly reduced the recurrence of migraine 24 to 72 hours after treatment compared with placebo (7 studies, n=738; RR 0.74, 95% CI: 0.60, 0.90). Heterogeneity was not significant (I2=3.4%).
The addition of dexamethasone to standard abortive care did not significantly influence initial headache pain reduction (4 studies, n=455; WMD 0.37, 95% CI: -0.20, 0.94). There was moderate heterogeneity (I2=46.2%).
Six studies (n=626) reported specific adverse events. Patients treated with dexamethasone were more likely to have dizziness (RR 2.15, 95% CI: 0.98, 4.74), but less likely to have nausea (RR 0.70, 95% CI: 0.48, 1.02) or 'other' adverse events (RR 0.50, 95% CI: 0.30, 0.82). Only the result for 'other' adverse events was statistically significant. No significant differences were found between treatment groups for restlessness, drowsiness, tingling, numbness or swelling.
For the outcome of recurrent migraine, no significant differences were found between intramuscular and intravenous administration of dexamethasone.
The results for other subgroup analyses were reported.