Cost effectiveness of acute imipramine therapy versus two imipramine maintenance treatment regimens for panic disorder

Objective: To examine the medical costs and effectiveness of acute treatmen t with imipramine versus acute treatment plus 2 different maintenance thera pies for panic disorder. Methods: A clinical decision model was constructed to estimate 18-month cos ts and outcomes associated with these treatment scenarios based on the medi cal literature and clinician judgment. The clinical parameters and outcomes for the model were derived from a series of systematic clinical trials wit h imipramine utilising uniform dosage procedures and validated response cri teria. Costs were calculated based on standardised treatment regimens. The outcome measures were 18-month medical costs, quality-adjusted life years ( QALYs) and costs per QALY gained. A sensitivity analysis was performed to e xplore the impact of treatment withdrawals on outcomes. Study perspective: US mental healthcare system. Results: Over 18 months, the total costs (1997 values) and QALYs associated with half-dose maintenance therapy (imipramine 1.1 mg/kg/day) [$US3377; QA LYs = 0.991] and full-dose maintenance therapy (imipramine 2.25 mg/kg/day) [$US3361; QALYs = 0.991] were almost identical; both were cost saving compa red with acute imipramine therapy (2.25 mg/kg/day) with no maintenance trea tment ($US3691 : QALYs = 0.979). Whether patients withdrawing from treatmen t were considered to have continued to respond to treatment or to have rela psed, the half-dose and full-dose maintenance treatments were still cost sa ving compared with acute treatment alone. Conclusions: The results indicate that imipramine maintenance treatment is cost effective compared with acute imipramine treatment for patients with p anic disorder. The basic findings and conclusions are not affected after mo difying model assumptions for clinical response in patients withdrawing fro m treatment.