OBJECTIVES: To examine the accuracy of subjects’ understanding of how to report migraine severity on a single item PRO measure.

METHODS: Participants responded to a question on an online survey pertaining to the severity of migraine headaches. Participants were then given a two-sentence training defining “migraine severity” and asked respond to the initial question.

RESULTS: Six hundred twenty three participants responded to the question “You are participating in a clinical trial relating to migraines and are asked to rate the level of your most severe headache over the past 24 hours, on a scale from 0-10. During the past day, the intensity of your headache has changed from a 7 in the morning to a 3 in the evening.” Only 275 (44%) of subjects responded to the question correctly (rating score of 7).

After viewing a two sentence training on the concept of migraine headache severity, the number of participants who answered the question correctly increased to 408 (65%). Of those who initially answered the question incorrectly a significant number of participants, 157 (25%) provided the correct response (p < 0.0001 McNemar Test).

CONCLUSIONS: The FDA PRO guidance indicates that concepts being measured in a PRO should be explicitly defined. Subjects understanding of the questions and response options is paramount to the integrity of critical data as many PROs contribute to primary or key secondary endpoints in pivotal clinical trials.

As this study demonstrates, when people were asked to rate the severity of migraines headaches, results revealed that without specific training on “migraine severity,” most people failed to choose the correct response. As indicated in this study, subjects’ understanding can significantly improve with training such as providing guidance on key concepts.