Is low antiepileptic drug dose effective in long-term seizure-free patients?

Objective: To investigate the value of leaving seizure-free patients on low-dose medication.

Method: This was an exploratory prospective randomized study conducted at our University Hospital. We evaluated the frequency of seizure recurrence and its risk factors following complete or partial antiepileptic drug (AED) withdrawal in seizure free patients for at least two years with focal, secondarily generalized and undetermined generalized epilepsies. For this reason, patients were divided into two groups: Group 1 (complete AED withdrawal), and Group 2 (partial AED withdrawal). Partial AED withdrawal was established as a reduction of 50% of the initial dose. Medication was tapered off slowly on both groups. Follow-up period was 24 months.

Results: Ninety-four patients were followed up: 45 were assigned to complete (Group 1) AED withdrawal and 49 to partial (Group 2) AED withdrawal. Seizure recurrence frequency after two years follow-up were 34.04% in group 1 and 32.69% in Group 2. Survival analysis showed that the probability of remaining seizure free at 6, 12, 18 and 24 months after randomization did not differ between the two groups (p = 0.8). Group 1: 0.89, 0.80, 0.71 and 0.69; group 2: 0.86, 0.82, 0.75 and 0.71. The analysis of risk factors for seizure recurrence showed that more than 10 seizures prior to seizure control was a significant predictive factor for recurrence after AED withdrawal (hazard ratio = 2.73).

Conclusion: Leaving seizure free patients on low AED dose did not reduce the risk for seizure recurrence. That is, once the decision of AED withdrawal has been established, it should be complete.