Association of antiseizure medication adherence with illness perceptions in adults with epilepsy.

Objective: We assessed the relationship of epilepsy illness perceptions to antiseizure medication (ASM) adherence.

Methods: Surveys were completed by 644 adult patients with epilepsy of unknown cause. We used the Morisky Medication Adherence Scale-8 (MMAS-8) to define "high" adherence (score = 8) and "low-medium" adherence (score < 8). We evaluated epilepsy illness perceptions using seven items from the Brief Illness Perception Questionnaire (BIPQ), each scored from 0-10, measuring participants' views of the overall effect of epilepsy on their lives, how long it would last, how much control they had over their epilepsy, the effectiveness of their treatment, level of concern about epilepsy, level of understanding of epilepsy, and emotional impact of epilepsy. We investigated the association of each BIPQ item with medication adherence using logistic regression models that controlled for potential confounders (age, race/ethnicity, income, and time since the last seizure).

Results: One hundred forty-nine patients (23%) gave responses indicating high adherence. In the adjusted models, for each 1-unit increase in participants' BIPQ item scores, the odds of high adherence increased by 17% for understanding of their epilepsy (OR = 1.17, 95% CI 1.07-1.27, p < 0.001), decreased by 11% for overall life impact of epilepsy (OR = 0.89, 95% CI 0.82-0.97, p = 0.01) and decreased by 6% for emotional impact of epilepsy (OR = 0.94, 95% CI 0.86-0.99, p = 0.03). No other illness perception was associated with high adherence. Depression, anxiety, and stigma mediated the inverse relationships of high adherence to the overall life impact of epilepsy and the emotional impact of epilepsy. These measures did not mediate the relationship of high adherence to the perceived understanding of epilepsy.

Conclusion: These results indicate that a greater perceived understanding of epilepsy is independently associated with high ASM adherence. Programs aimed at improving patients' understanding of their epilepsy may help improve medication adherence.