To evaluate the cost effectiveness of intrathecal drug therapy (IDT) compared with conventional medical management (CMM) for patients with refractory chronic noncancer pain.
A probabilistic Markov model was developed to evaluate the cost effectiveness of IDT versus CMM from the perspective of a Canadian provincial Ministry of Health using data from our pain clinic. The model followed costs and outcomes in 6-month cycles. Health effects were expressed as quality-adjusted life years (QALYs) gained. Resources use included drugs, physician visits, laboratory tests, scans, and hospitalizations. Unit costs were gathered from public sources and were expressed in 2011 Canadian dollars. Costs and effects were evaluated over a time horizon of 10 years and discounted at 5% per annum after the first year. Cost effectiveness was identified by deterministic and probabilistic sensitivity analyses (50,000 Monte Carlo iterations).
Over 10 years, total costs were $61,442 for IDT and $48,408 for CMM. Thus, the incremental effectiveness of IDT was 1.1508 QALYs at an incremental cost of $13,034, resulting in an incremental cost-effectiveness ratio of $11,326/QALY gained. The probability of IDT providing a cost-effective alternative to CMM was 50% and 84% at a willingness-to-pay threshold of $14,200 and $20,000/QALY, respectively. The results were most sensitive to the cost of CMM, the probability of reaching an optimal health state with dual-drug IDT, and the effectiveness of CMM therapy. Sensitivity analyses showed that results were robust to plausible variations in model costs and effectiveness inputs.
IDT is cost effective compared with CMM in the management of chronic noncancer pain.