title: Economic evaluation of a behavior-modifying intervention to enhance antiepileptic drug adherence.
abstract: Between 35% and 50% of patients with epilepsy are reported to be not fully adherent to their medication schedule. We aimed to conduct an economic evaluation of strategies for improving adherence to antiepileptic drugs. Based on the findings of a systematic review, we identified an implementation intention intervention (specifying when, where, and how to act) which was tested in a trial that closely resembled current clinical management of patients with epilepsy and which measured adherence with an objective and least biased method. Using patient-level data, trial patients were matched with those recruited for the Standard and New Antiepileptic Drugs trial according to their clinical characteristics and adherence. Generalized linear models were used to adjust cost and utility in order to estimate the incremental cost per quality-adjusted life-year (QALY) gained from the perspective of the National Health Service in the UK. The mean cost of the intervention group, £1340 (95% CI: £1132, £1688), was marginally lower than that of the control group representing standard care, £1352 (95% CI: £1132, £1727). Quality-adjusted life-year values in the intervention group were higher than those in the control group, i.e., 0.75 (95% CI: 0.70, 0.79) compared with 0.74 (95% CI: 0.68, 0.79), resulting in a cost saving of £12 (€15, US$19) and with the intervention being dominant. The probability that the intervention is cost-effective at a threshold of £20,000 per QALY is 94%. Our analysis lends support to the cost-effectiveness of a self-directed, implementation intention intervention for improving adherence to antiepileptic drugs. However, as with any modeling dependent on limited data on efficacy, there is considerable uncertainty surrounding the clinical effectiveness of the intervention which would require a substantive trial for a more definitive conclusion.
authors.affiliation: Centre for Health Economics and Medicines Evaluation, Bangor University, Ardudwy, Normal Site, Holyhead Road, Bangor LL57 2PZ, UK.
authors.forename: Catrin O
authors.initials: CO
authors.lastname: Plumpton
authors.affiliation: Clinical Psychology Unit, Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Brown
authors.affiliation: Academic Neurology Unit, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield S10 2JF, UK.
authors.forename: Markus
authors.initials: M
authors.lastname: Reuber
authors.affiliation: Department of Molecular and Clinical Pharmacology, Liverpool University, Division of Neurology, The Walton Centre, Liverpool L69 3GL, UK.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Marson
authors.affiliation: Centre for Health Economics and Medicines Evaluation, Bangor University, Ardudwy, Normal Site, Holyhead Road, Bangor LL57 2PZ, UK. Electronic address: d.a.hughes@bangor.ac.uk.
authors.forename: Dyfrig A
authors.initials: DA
authors.lastname: Hughes
mesh_terms: D000328:Adult; D000927:Anticonvulsants / Q000627:therapeutic use*; D001521:Behavior Therapy / Q000191:economics* / Q000379:methods; D003362:Cost-Benefit Analysis / Q000191:economics* / Q000379:methods; D061345:Early Medical Intervention / Q000191:economics* / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D055118:Medication Adherence / Q000523:psychology; D008875:Middle Aged
chemical_list: D000927:Anticonvulsants
keywords: Adherence; Antiepileptic drug; Cost-effectiveness analysis; Economic evaluation