Aims: Valproic acid (VPA) is reported to be effective for the control of absence seizures in 75% of children. The aim of this study was to determine the clinical and socio-demographic factors associated with VPA response in newly diagnosed childhood absence epilepsy (CAE) and to determine if these factors also influence the chances of achieving long-term seizure freedom.
Methods: Medical charts of 180 children with CAE were retrospectively reviewed. Clinical, electroencephalographic and imaging findings were recorded to correlate with complete VPA response and long-term epilepsy outcome. Factors associated with non-responsiveness were identified individually and in a multivariable logistic regression analysis.
Results: Treatment was successful in 112 (58.3%) children. More children that were non-responsive to VPA experienced generalized tonic clonic seizures (GTCS) (33.8% vs. 13.4% for responders; p=0.001) and 52.9% had a pre-treatment seizure frequency greater than 10/day (vs. 27.0% for responders; p<0.001). Finally, responders were older at time of diagnosis versus non-responders (p=0.001). Absence of long-term seizure freedom was linked to the presence of GTCS, the absence of initial response and the need for multiple AEDs to control seizures.
Interpretation: Our results suggest that clinical phenotypes are associated with reduced response rates to VPA. This should be taken into account when counselling families of children with newly diagnosed absence epilepsy.