Intrapatient variability of migraine attacks: stability analysis of the MIGSEV scale

Various tools now exist to define migraine and its impact on everyday life. Those are scales that help diagnosing the disease and managing treatment. However, there is no such emphasis on defining individual migraine attacks and their variability. Yet, as a chronic disease with variable frequency and intensity among individuals, there should be a way of developing the management of the disease based on knowledge of the attacks.

To determine the variability of the severity of migraine attacks over time in individual patients using the MIGSEV scale.

A set of migraineurs recruited in general practice filled a diary about their attacks during a 3-month period. The MIGSEV scale was used to determine the severity of their attacks, which could be mild, moderate, or severe. A Markov model was then adjusted with those 3 states and explanatory variables were considered as possible covariates.

Probabilities were estimated that enabled to expect the severity of an attack to come, given the severity of the previous one. For instance, no matter the profile of the patient, the severity of an attack had more chances of being similar to the previous one: 74% of remaining mild, 60% of remaining moderate, and 55% of remaining severe. When it was not similar, having an attack milder than the previous one was more likely than having a more severe attack. For example, the probability of going from moderate to severe was 0.105 whereas the probability of going from moderate to mild was 0.219. Covariates had no significant effect on estimated probabilities.

An important aspect of the illness was defined here: the severity profile of patients. The MIGSEV is stable over time and severity of individual attacks represents a significant indicator in the characterization of the disease.