Case-control analysis of ambulance, emergency room, or inpatient hospital events for epilepsy and antiepileptic drug formulation changes.
OBJECTIVE
Although antiepileptic drugs (AEDs) with multisource generic alternatives are becoming more prevalent, no case-control studies have been published examining multisource medication use and epilepsy-related outcomes. This study evaluated the association between inpatient/emergency epilepsy care and the occurrence of a recent switch in AED formulation.


METHODS
A case-control analysis was conducted utilizing the Ingenix LabRx Database. Eligible patients were 12-64 years of age, received >or=145 days of AEDs in the preindex period, had continuous eligibility for 6 months preindex, and no prior inpatient/emergency care. Cases received care between 7/1/2006 and 12/31/2006 in an ambulance, emergency room, or inpatient hospital with a primary epilepsy diagnosis. Controls had a primary epilepsy diagnosis in a physician's office during the same period. The index date was the earliest occurrence of care in each respective setting. Cases and controls were matched 1:3 by epilepsy diagnosis and age. Odds of a switch between "A-rated" AEDs within 6 months prior to index were calculated.


RESULTS
Cases (n = 416) had 81% greater odds of having had an A-rated AED formulation switch [odds ratio (OR) = 1.81; 95% confidence interval (CI) = 1.25 to 2.63] relative to controls (n = 1248). There were no significant differences between groups regarding demographics or diagnosis. Significant differences were found with regard to medical coverage type (case Medicaid = 4.6%, control Medicaid = 1.8%, p = 0.002). Post hoc analysis results excluding Medicaid recipients remained significant and concordant with the original analysis.


CONCLUSIONS
This analysis found an association between patients receiving epilepsy care in an emergency or inpatient setting and the recent occurrence of AED formulation switching involving A-rated generics.
Zachry
Woodie M
WM
Abbott Laboratories, Abbott Park, Illinois, USA. woodie.zachry@abbott.com
Doan
Quynhchau D
QD
Clewell
Jerry D
JD
Smith
Brien J
BJ
D000328:Adult; D000552:Ambulances; D000927:Anticonvulsants / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D016022:Case-Control Studies; D017046:Cost Savings; D016527:Drug Costs / Q000706:statistics & numerical data; D016568:Drugs, Generic / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D004632:Emergency Medical Services; D004636:Emergency Service, Hospital; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics; D004829:Epilepsy, Generalized / Q000175:diagnosis / Q000188:drug therapy* / Q000191:economics; D005260:Female; D006801:Humans; D007555:Isoxazoles / Q000009:adverse effects / Q000191:economics / Q000627:therapeutic use*; D008297:Male; D008484:Medicaid / Q000191:economics; D008875:Middle Aged; D016017:Odds Ratio; D010343:Patient Admission; D012189:Retrospective Studies; D013810:Therapeutic Equivalency; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult; D000078305:Zonisamide
D000927:Anticonvulsants; D016568:Drugs, Generic; D007555:Isoxazoles; D000078305:Zonisamide