[Cost-benefit evaluation of spinal cord stimulation treatment for failed-back surgery syndrome patients]

A review of economic factors related to the delivery of health care for chronic low back pain

INTRODUCTION AND METHODS

We describe tools used to evaluate the economic impact of health care interventions, discuss the economic burden of chronic low back pain, and review evidence on the cost-effectiveness of treating failed back surgery syndrome with spinal cord stimulation, intrathecal drug delivery, acupuncture, epidural injections, disc prosthesis, lumbar fusion, and noninvasive therapies. We also mention the lack of cost studies for emerging therapies, such as vibrotherapy and peripheral nerve field stimulation. Topics include types of cost studies; the economic perspectives taken by such studies; direct and indirect costs; measures of success; definitions of cost-effectiveness, incremental cost-effectiveness, incremental cost-utility ratios, and quality-adjusted life years; the concept of maximum willingness to pay; and the use of cost-effectiveness models.

CONCLUSION

The fact that chronic low back pain arises from a variety of causes makes choosing appropriate treatment difficult. Determining the cost-effectiveness of various treatments for chronic low back pain depends on well-designed and well-executed randomized controlled trials with parallel economic evaluations. Researchers can use economic models to extrapolate costs and outcomes over the long term.

Back Pain: A Real Target for Spinal Cord Stimulation?

Background:

Failed back surgery syndrome represents one of the most frequent etiologies of chronic back pain and is a major public health issue. Neurostimulation has currently not been validated in the treatment of back pain because of technological limitations in implantable spinal cord stimulation (SCS) systems. New-generation leads using several columns of stimulation can generate longitudinal and/or transverse stimulation fields into the spinal cord.

Objective:

To investigate, through extensive stimulation testing, the capacity of multicolumn tripolar leads to achieve back territory paresthesia coverage in refractory failed back surgery syndrome patients.

Methods:

Eleven patients implanted with a 16-contact spinal cord stimulation lead (Specify 5-6-5, Medtronic Inc) were assessed with a systematic exploration of 43 selected stimulation configurations to generate bilateral back paresthesia in addition to leg territory coverage.

Results:

The tripolar lead successfully generated paresthesia in both bilateral back and leg territories in 9 patients (81.8%). Success rates of multicolumn stimulation patterns were significantly higher than for longitudinal configurations for lombodorsal paresthesia coverage. Six months after implantation, significant pain relief was obtained compared with preoperative evaluation for global pain (Visual Analog Scale, 2.25 vs 8.2 preoperatively; P < .05), leg pain (Visual Analog Scale, 0.5 vs 7.6 preoperatively; P < .05), and back pain (Visual Analog Scale, 1.5 vs 7.8 preoperatively; P < .05).

Conclusion:

These results suggest that multicolumn leads can reliably generate back pain coverage and favor pain relief outcomes. This may lead physicians to reconsider new indications for spinal cord stimulation. Expanding neurostimulation perspectives to intractable back pain syndromes could become realistic in the near future.

Neuropathic pain: quality-of-life impact, costs and cost effectiveness of therapy

A number of different diseases or injuries can damage the central or peripheral nervous system and produce neuropathic pain (NP), which seems to be more difficult to treat than many other types of chronic pain. As a group, patients with NP have greater medical co-morbidity burden than age- and sex-adjusted controls, which makes determining the humanistic and economic burden attributable to NP challenging. Health-related quality of life (HR-QOL) is substantially impaired among patients with NP. Patients describe pain-related interference in multiple HR-QOL and functional domains, as well as reduced ability to work and reduced mobility due to their pain. In addition, the spouses of NP patients have been shown to experience adverse social consequences related to NP. In randomized controlled trials, several medications have been shown to improve various measures of HR-QOL. Changes in HR-QOL appear to be tightly linked to pain relief, but not to the development of adverse effects. However, in cross-sectional studies, many patients continue to have moderate or severe pain and markedly impaired HR-QOL, despite taking medications prescribed for NP. The quality of NP treatment appears to be poor, with few patients receiving recommended medications in efficacious dosages. The substantial costs to society of NP derive from direct medical costs, loss of the ability to work, loss of caregivers' ability to work and possibly greater need for institutionalization or other living assistance. No single study has measured all of these costs to society for chronic NP. The cost effectiveness of various interventions for the treatment or prevention of different types of NP has been assessed in several different studies. The most-studied diseases are post-herpetic neuralgia and painful diabetic neuropathy, for which tricyclic antidepressants (both amitriptyline and desipramine) have been found to be either cost effective or dominant relative to other strategies. Increasing the use of cost-effective therapies such as tricyclic antidepressants for post-herpetic neuralgia and painful diabetic neuropathy may improve the HR-QOL of patients and decrease societal costs. Head-to-head clinical trials comparing NP therapies are needed to help assess the relative clinical efficacy of treatments, ideally using HR-QOL and utility outcomes. The full costs to society of NP, including productivity loss costs, have not been determined for chronic NP. Improved relative efficacy, utility and cost estimates would facilitate future cost-effectiveness research in NP.

Spinal Cord Stimulation versus Reoperation for Failed Back Surgery Syndrome: A Cost Effectiveness and Cost Utility Analysis Based on a Randomized, Controlled Trial

OBJECTIVE:

We analyzed the cost-effectiveness and cost–utility of treating failed back–surgery syndrome using spinal cord stimulation (SCS) versus reoperation.

MATERIALS AND METHODS

A disinterested third party collected charge data for the first 42 patients in a randomized controlled crossover trial. We computed the difference in cost with regard to success (cost–effectiveness) and mean quality–adjusted life years (cost–utility). We analyzed the patient–charge data with respect to intention to treat (costs and outcomes as a randomized group), treated as intended (costs as randomized; crossover failure assigned to a randomized group), and final treatment costs and outcomes.

RESULTS:

By our mean 3.1–year follow–up, 13 of 21 patients (62%) crossed to reoperation versus 5 of 19 patients (26%) who crossed to SCS (P < 0.025). The mean cost per success was US $117,901 for crossovers to SCS. No crossovers to reoperation achieved success despite a mean per-patient expenditure of US $260,584. The mean per-patient costs were US $31,530 for SCS versus US $38,160 for reoperation (intention to treat), US $48,357 for SCS versus US $105,928 for reoperation (treated as intended), and US $34,371 for SCS versus US $36,341 for reoperation (final treatment). SCS was dominant (more effective and less expensive) in the incremental cost–effectiveness ratios and incremental cost–utility ratios. A bootstrapped simulation for incremental costs and quality–adjusted life years confirmed SCS's dominance, with approximately 72% of the cost results occurring below US policymakers' “maximum willingness to pay” threshold.

CONCLUSION:

SCS was less expensive and more effective than reoperation in selected failed back–surgery syndrome patients, and should be the initial therapy of choice. SCS is most cost–effective when patients forego repeat operation. Should SCS fail, reoperation is unlikely to succeed.