Development and exploration of the content validity of a patient-reported outcome measure to evaluate the impact of migraine- the migraine physical function impact diary (MPFID)

Background: Adults with migraine experience substantial reductions in quality of life during and in-between migraine attacks. Clinical and regulatory guidelines encourage the inclusion of patient reported outcomes for the evaluation of benefits of interventions for migraine. Methods: The conceptual framework and items for a new patient-reported outcome (PRO) instrument, the Migraine Physical Function Impact Diary (MPFID), were developed using scientific methods recommended to ensure content validity of PRO instruments. The MPFID was developed to measure the impact of migraine on physical functioning based on themes raised in concept elicitation (CE) interviews (conducted previously) with adults with migraine. Cognitive interviews were conducted with adults with migraine to further explore content validity. The instrument was modified following an interim analysis of a first round of cognitive interviews, to assess comprehensiveness and clarity of items, instructions, and response options. Refinements were subsequently tested in additional cognitive interviews. Results: The conceptual framework included impacts on physical functioning experienced by most adults with migraine and deemed clinically relevant for measuring the outcome of an intervention for migraine. Concepts in the framework included the impact of migraine on physical impairments (acts) and ability to complete day-to-day activities and perform everyday activities (tasks). MPFID items were generated to evaluate functioning over the past 24h and to collect data daily, to capture experiences on days with migraine as well as the days in-between migraines. Items asked about needing to rest or lie down; ability to get out of bed, stand up, bend over, walk, perform household chores, do tasks outside the home, keep routines or schedules, get ready for the day, do activities that require concentration or clear thinking; difficulty moving head and body, doing activities requiring physical effort; avoiding interacting with others. Initial modifications based on the first round of cognitive interviews (n=8) included clarifying instructions, updating three items to enhance specificity and clarity, and revising one item to include gender-neutral language. The second round of interviews (n=9) confirmed acceptability of revisions and supported content validity. Conclusions: The results provide qualitative evidence supporting the content validity of the MPFID for evaluating outcomes of interventions for migraine.