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 treatment with imipramine versus acute treatment plus 2 different maintenance therapies for panic disorder.

METHODS

A clinical decision model was constructed to estimate 18-month costs and outcomes associated with these treatment scenarios based on the medical literature and clinician judgment. The clinical parameters and outcomes for the model were derived from a series of systematic clinical trials with imipramine utilising uniform dosage procedures and validated response criteria. 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 explore 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) [$US3377; QALYs = 0.991] and full-dose maintenance therapy (imipramine 2.25 mg/kg/ day) [$US3361; QALYs = 0.991] were almost identical; both were cost saving compared with acute imipramine therapy (2.25 mg/kg/day) with no maintenance treatment ($US3691; QALYs = 0.979). Whether patients withdrawing from treatment were considered to have continued to respond to treatment or to have relapsed, the half-dose and full-dose maintenance treatments were still cost saving compared with acute treatment alone.

CONCLUSIONS

The results indicate that imipramine maintenance treatment is cost effective compared with acute imipramine treatment for patients with panic disorder. The basic findings and conclusions are not affected after modifying model assumptions for clinical response in patients withdrawing from treatment.