title: Changes in medication associated with epilepsy-related hospitalisation: a case-crossover study.
abstract: OBJECTIVE
  To assess the association between changes in medication and epilepsy-related hospitalisation.
  
  
  METHODS
  Data were obtained from the PHARMO Record Linkage System (Jan 1998 to Dec 2002). We conducted a case-crossover study among patients with a first epilepsy-related hospital admission who had continuously used at least one antiepileptic drug (AED) during a 28-week period before admission. For each patient, changes in medication in a 28-day window before hospitalisation were compared with changes in four earlier 28-day windows. Evaluated changes were: changes in AEDs (pattern and dosage), changes in interacting co-medication and changes in non-interacting co-medication (i.e. introduction of non-interacting drugs). The strength of the association between changes in medication and epilepsy-related hospitalisation was estimated using conditional logistic regression analysis and expressed as odds ratios (ORs) with 95% confidence intervals (CI).
  
  
  RESULTS
  Out of 1185 patients with a first epilepsy-related hospitalisation, 217 patients met the inclusion criteria. Of the changes in antiepileptic therapy, discontinuation showed a trend towards an increased risk of hospitalisation (OR: 2.57; 95%CI: 0.81-8.17). Drug interactions influencing antiepileptic therapy rarely occurred. Introduction of three or more non-interacting drugs was significantly associated with epilepsy-related hospitalisation (OR: 4.80; 95%CI: 2.12-10.87). Of individual drugs, addition of antimicrobial agents was significantly associated with epilepsy-related hospitalisation (OR: 1.99; 95%CI: 1.06-3.75).
  
  
  CONCLUSIONS
  Changes in AED therapy were not significantly associated with epilepsy-related hospitalisation and few drug interactions influencing antiepileptic therapy occurred. However, patients starting three or more new non-AEDs had a nearly five times increased risk of epilepsy-related hospital admission.
authors.affiliation: Department of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
authors.forename: Kim B
authors.initials: KB
authors.lastname: Handoko
authors.forename: Jeannette E F
authors.initials: JE
authors.lastname: Zwart-van Rijkom
authors.forename: Walter A J J
authors.initials: WA
authors.lastname: Hermens
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Souverein
authors.forename: Toine C G
authors.initials: TC
authors.lastname: Egberts
mesh_terms: D000328:Adult; D000368:Aged; D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use*; D016022:Case-Control Studies; D015331:Cohort Studies; D018592:Cross-Over Studies; D004334:Drug Administration Schedule; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy* / Q000453:epidemiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D012042:Registries / Q000706:statistics & numerical data; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D000927:Anticonvulsants