First, a short list of outcomes to enter the consensus process was required, and this informed by looking at which outcomes were already measured in the published literature. We analysed 104 consecutive phase III and IV clinical trial records from the past 15 years from the clinicaltrials.gov and ISRCTN clinical trial registries, and examined their associated publications.  For each of these publications we extracted data on the trial type, population, intervention, the outcomes being measured and the associated outcome measurement instruments.

This was also supplemented by the lived experience perspective, by reviewing published data from focus groups, in-depth interviews and other qualitative data discussing outcomes or goals of treatment with people living with epilepsy.  Here we examined 75 studies, representing the views of over 2300 people with epilepsy.

Once a long list of 180 outcome terms had been created, this was rationalised and condensed by members of the research team and patient, public collaborators into a more meaningful list of 42 outcome domains that was taken forward to our consensus exercise.

Delphi process

The 42 short listed outcomes were subject to an internaitonal 2-round online Delphi consensus exercise were participants were asked to vote on which outcomes "are absolutely essential to measure in all interventional studies" in 2022.  In total there were 534 registrations for the survey, and 490 completed round 1 responses, representing a 91% completion rate.  We had participants from a wide range of countries with representation from all 6 continents, and responses completed in the 7 language versions that were available.  There was good representation from people with lived experience, with adults with epilepsy and their caregivers, representing 61% of round 1 responses and 56% of round 2 responses

The final EPSET project Core Outcome Set included 10 outcomes that were deemed critical to measure in adult epilepsy effectivenes studies by all the stakeholder groups:  seizure frequency, seizure freedom, episodes of status epilepticus, HRQOL, overall health status, symptoms of depression and suicidality, side effects and their severity, and mortality.