The effectiveness of parenteral agents to mitigate relapses after severe acute migraine headache presentations: A systematic review and network analysis.

Objectives: To compare the effectiveness of parenteral agents to reduce relapse in patients with acute migraine and identify factors that predict relapse.

Background: Following discharge from emergency settings, many patients with acute migraine will experience a relapse in pain; severe relapses may result in re-visits to emergency settings.

Methods: A comprehensive literature search, updated to 2023, was conducted to identify randomized controlled trials assessing the effectiveness of parenteral agents on relapse outcomes in patients with acute migraine discharged from emergency settings. Two independent reviewers completed study selection, quality assessment, and data extraction. A traditional meta-analysis compared parenteral corticosteroids to placebo; a frequentist network analysis assessed direct and indirect comparisons. Results are reported as risk ratios (RRs) and 95% confidence intervals (CIs). The review protocol was registered with the International Prospective Register of Systematic Reviews (identifier: CRD42018099493).

Results: From 8949 citations, a total of 53 unique studies were included involving 6167 patients. Most studies had a high or unclear risk of bias. Corticosteroids significantly reduced relapses compared to placebo (RR 0.67, 95% CI 0.52-0.88; I² = 0%). Patients receiving lidocaine (RR 0.10, 95% CI 0.01-0.82), sedatives/hypnotics (RR 0.33, 95% CI 0.14-0.75), ergot agents (RR 0.44, 95% CI 0.25-0.75), neuroleptics (RR 0.47, 95% CI 0.31-0.71), opioids (RR 0.58; 95% CI 0.35-0.94), or corticosteroids (RR 0.64, 95% CI 0.47-0.86) were significantly less likely to relapse. Lidocaine (RR 0.09, 95% CI 0.01-0.71), combination therapy (RR 0.12, 95% CI 0.02-0.74), or adding corticosteroids (RR 0.61, 95% CI 0.44-0.84) were more likely to reduce severe relapses. Longer duration of headache and residual pain at discharge were significantly associated with higher relapses.

Discussion: Corticosteroids remain the recommended first-line option to reduce relapse outcomes. Some parenteral agents typically provided for pain relief including ergot agents, neuroleptics, or combination therapy may effectively reduce relapse; however, opioids are not recommended due to safety concerns. Additional research is needed for some lesser studied, albeit promising, agents including lidocaine and propofol. Effective pain control in emergency settings prior to discharge and duration of headache may play a role in the success of such treatments and further investigations could provide further insight regarding how and why some parenteral agents are effective in mitigating relapse events.