Cost-Effectiveness Model Shows Superiority of Wireless Spinal Cord Stimulation Implantation Without a Separate Trial

Abstract

Objective: We evaluated the cost-effectiveness of wireless spinal cord stimulation (Wireless SCS) with single stage "direct to permanent" implantation vs. screening with temporary electrodes and an external pulse generator followed by implantation of a system for long-term use (IPG SCS).

Materials and methods: We created a cost model that takes a 2019 United States (U.S.) payer perspective and is based on IPG SCS cost models for subjects with chronic back and/or leg pain. Our six-month decision tree includes the screening trial period (success ≥50% relief) and leads to various levels of pain relief with or without complications for IPG SCS and Wireless SCS and without complications for conventional medical management (CMM). Every three months in the follow-on 15-year Markov model (with costs and quality-adjusted life years discounted 3.5% annually), subjects remain stable or transition to deteriorated health or death. Subjects who fail SCS receive CMM. After 60 Markov cycles, a 100,000-sample simulation reveals the impact of maximum willingness-to-pay (WTP) from $10,000 to $100,000 per quality-adjusted life year on net monetary benefit (NMB). Sensitivity analyses considered the impact of the Wireless SCS screening success rate, Wireless SCS device cost, and IPG SCS device longevity.

Results: Compared with IPG SCS, Wireless SCS offers higher clinical effectiveness at a lower cost and a higher NMB for our WTP thresholds and is, thus, dominant. Wireless SCS is also cost-effective compared with CMM. Results remain robust with 1) Wireless SCS screening success rates as low as 85% (dominant), 2) the cost of the Wireless SCS devices as high as $55,000 (cost-effective), and 3) IPG SCS devices lasting 12 years (dominant).

Conclusions: In this model, compared with IPG SCS or with CMM, Wireless SCS is a superior strategy.

Keywords: Cost-effectiveness; SCS health economics; modeling study; spinal cord stimulation; wireless SCS.

Figure 1

The first six months of treatment are represented by a decision tree that illustrates pathways to potential outcomes for patients receiving IPG SCS, Wireless SCS, or CMM alone. Success and optimal pain relief are defined as >50% pain reduction from baseline on a pain rating scale; suboptimal pain relief is more than zero and <50% pain reduction.

Figure 2

The 15 years following the decision tree period are represented by a Markov model. The definitions of optimal (> 50% reduction from baseline) and suboptimal (< 50% reduction) pain relief remain the same, as does the progression of SCS failure to CMM.

Figure 3

Cost‐effectiveness graph showing that Wireless SCS is dominant compared with IPG SCS and that both SCS therapies provide a lower cost/QALY versus CMM.

Figure 4

Net monetary benefit (NMB) versus willingness to pay (WTP).

Figure 5

Tornado diagram representing one‐way sensitivity analyses showing the impacton the INMB associated with Wireless SCS when assumptions are varied.

Figure 6

One‐way sensitivity analysis of IPG replacement in years.

Figure 7

One‐way sensitivity analysis of Wireless SCS trial success (%).

Figure 8

One‐way sensitivity analysis of the cost of the Wireless SCS device.