title: Risk factors for valproic acid resistance in childhood absence epilepsy.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Paediatrics, Division of Neurology, CHU Sainte-Justine, 3175 Côte-Ste-Catherine, Montreal, Quebec, H3T 1C5 Canada. may_lissa_ollivier@hotmail.com
authors.forename: May Lissa
authors.initials: ML
authors.lastname: Ollivier
authors.forename: Marie France
authors.initials: MF
authors.lastname: Dubois
authors.forename: Maja
authors.initials: M
authors.lastname: Krajinovic
authors.forename: Patrick
authors.initials: P
authors.lastname: Cossette
authors.forename: Lionel
authors.initials: L
authors.lastname: Carmant
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000139:chemically induced* / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D011237:Predictive Value of Tests; D012307:Risk Factors; D016896:Treatment Outcome; D014635:Valproic Acid / Q000009:adverse effects* / Q000627:therapeutic use*
chemical_list: D000927:Anticonvulsants; D014635:Valproic Acid