COST-EFFECTIVENESS OF LONG-TERM INTRATHECAL MORPHINE THERAPY FOR PAINASSOCIATED WITH FAILED BACK SURGERY SYNDROME

A decision analytic study was conducted using computer simulation to p roject the outcomes in a simulated cohort of patients whose treatment for back surgery had failed. The objective of this study was to estima te the direct cost of intrathecal morphine therapy (IMT) delivered via an implantable pump relative to alternative therapy (medical manageme nt) over a 60-month course of treatment. IMT administered by way of an implantable pump can provide effective pain relief for selected patie nts whose less invasive treatment modalities have failed. Previous res earch suggested that a pump implant is less costly than alternative me thods providing comparable analgesia for treatment exceeding 12 to 18 months. However, those analyses did not include the cost of complicati ons or pump replacement. Scenarios representing the course of IMT, dev ised by a panel of experts, were represented as treatment pathways in a Monte Carlo simulation. Adverse event rates were drawn from publishe d data supplemented by expert judgment. Direct costs were based on a h ealth insurer paid claims perspective (direct costs) discounted at a 5 % annual rate. The cost-effectiveness of IMT was calculated based on a report of 65% to 81% ''good to excellent'' pain relief relative to al ternative (medical) management. With both adverse event probabilities and costs set at most likely (base case) values, the expected total co st of IMT over 60 months was $82,893 (an average of $1382 per month). In a sensitivity analysis, the best case (low adverse event rate, low cost) estimate was $53,468 ($891/mo), whereas the worst case (high adv erse event rate, high cost) estimate was $125,102 ($2085/mo). Cost-eff ectiveness estimates ranged from $7212 (best case) to $12,276 (worst c ase) per year of pain relief. Results from a computer simulation desig ned to collect the costs not included in previous empiric research ind icate that IMT appears to be cost-effective when compared with alterna tive (medical) management for selected patients when the duration of t herapy exceeds 12 to 22 months.