An economic appraisal of carbamazepine, lamotrigine, phenytoin and valproate as initial treatment in adults with newly diagnosed epilepsy.

Abstract

We undertook an economic appraisal of four drugs used in monotherapy during the first 2 years of treatment for newly diagnosed patients with epilepsy: carbamazepine (CBZ), lamotrigine (LTG), phenytoin (PHT), and valproate (VPA). We adopted the cost-minimization model because, although no single trial compares all four drugs directly, the clinical trials comparing two or more of these drugs in newly diagnosed cases show no significant difference in efficacy between the drugs in terms of seizure frequency. Considered in the cost analyses were frequency of side effects, retention rates, medical consultations, inpatient and accident and emergency costs, laboratory investigations, and drug changes. A Delphi panel provided the treatment pathways, including frequency of clinical consultations, second-line monotherapy, and side-effects management. A sensitivity analysis was performed, varying the assumptions on which the calculations were based. Analysis was completed for a prospective, intention-to-treat perspective and also for those patients continuing the initial drug. The direct medical costs of 2-years therapy (intention-to-treat analysis) calculated for each trial were pound sterling 795-829 for CBZ, pound sterling 1,525-2,076 for LTG, pound sterling 736-768 for PHT, and pound sterling 868-884 for VPA. A sensitivity analysis provided similar relative estimates. We found that LTG for newly diagnosed patients is significantly more expensive in direct health service costs incurred. This analysis incorporated seizure control, side effects, and tolerability. We recommend that a similar type of analysis be considered as part of all clinical trials of antiepileptic drugs in which efficacy of outcome is similar as a guide to assess optimal cost effectiveness.