Knowledge of environmental triggers for migraine attacks is limited and has mostly been acquired by studies using emergency room (ER) visits. However, it is unlikely that ER visits are a random sample of migraine events, even within strata of migraine severity. Additionally, time lags between attack onset and ER visits may vary across the population, posing challenges for assessing causal links of migraine with community-level or ecologic exposures.

Our objective was to assess the relationship between demographic and geographic measures and self-reported migraine-related ER visits.

We analyzed a targeted non-probability survey of ER use related to migraine in Canada and the USA. The 18-question online survey addressed ER use and behaviors related to recording attacks.

The final dataset included 389 respondents (Canada = 164 [42.2%], USA = 225 [57.8%]); 51 (13.1%) were Migraine Buddy app users who shared their diaries. In both countries, participants reported similar migraine symptoms. Barriers to attending the ER included cost and wait times. There was more variability in delays between attack onset and arrival to the ER than between onset and recording in the smartphone app. Younger participants and participants living in Canada were significantly more likely to present to the ER.

The sample of patients presenting to the ER for migraine may be biased toward younger patients and depend on the jurisdiction. Smartphone app records may have fewer barriers to creation and more consistent time lags compared to ER visit records.

We have updated the migraine prevention guideline of the Canadian Headache Society from 2012, as there are new therapies available, and additionally, we have provided guidelines for the prevention of chronic migraine, which was not addressed in the previous iteration.

We undertook a systematic review to identify new studies since the last guideline. For studies identified, we performed data extraction and subsequent meta-analyses where possible. We composed a summary of the evidence found and undertook a modified Delphi recommendation process. We provide recommendations for treatments identified and additionally expert guidance on the use of the treatments available in important clinical situations.

We identified 61 studies that were included in this evidence update and identified 16 therapies we focused on. The anti-calcitonin gene-related peptide (CGRP) agents were approved by Health Canada between 2018 and 2024 and provide additional options for episodic and chronic migraine prevention. We also summarize evidence for the use of propranolol, topiramate and onabotulinumtoxinA in addition to anti-CGRP agents as treatments for chronic migraine. We have downgraded topiramate to a weak recommendation for use and gabapentin to a weak recommendation against its use in episodic migraine. We have weakly recommended the use of memantine, levetiracetam, enalapril and melatonin in episodic migraine.

Based on the evidence synthesis, we provide updated recommendations for the prevention of episodic and chronic migraine utilizing treatments available in Canada. We additionally provided expert guidance on their use in clinical situations.