Clinical and cost effectiveness of SCS for chronic neuropathic or ischaemic pain

The National Institute for Health Research recently released the Health Technology Assessment (HTA) for Spinal Cord Assessment for chronic pain of neuropathic or ischaemic origin. It aims to provide information necessary for medical regulatory bodies to make decisions regarding the health technology under evaluation. The assessment presents data obtained from rigorous systematic analysis of valid and reliable studies published in the literature. Spinal cord stimulation (SCS) was systematically compared to conventional treatment strategies for clinical efficacy and safety, health and economic impact, management and incremental cost-effectiveness.1

Chronic pain is a highly distressing, debilitating and difficult to treat medical condition that can have detrimental effects on patients’ functionality, mood, work and relationships. As the population ages, the prevalence of conditions which provoke chronic pain will rise.¹

Dr Marc Russo, Specialist in Pain Medicine at Hunter Pain Clinic, believes chronic pain is a disease in its own right.

"Chronic pain can adversely affect mood status, work status, ability to conduct activities of daily living, recreational pursuits, external relationships with the outside world and personal relationships.

"Pain is never just pain, it is pain with the associated emotional distress and suffering, that is the relevant health issue."

Chronic pain has an enormous impact on the health budget as a consequence of treatment and disability payments as well as compensation for patients being unable to work and, in some cases, unable to care for themselves. A UK-based study has estimated that the prevalence of chronic neuropathic pain is 8.2%.¹

Dr Russo said, "Weighing above any other economic factor is the loss of productivity to society and the loss of productive benefit of an individual worker. The costs of both direct and indirect factors associated with chronic pain in Australia has been estimated to be at or higher than $34 billion by Access Economics."

SCS is vastly and rapidly emerging as a safe and efficacious alternative treatment for refractory chronic pain. SCS involves the implantation of electrodes into the epidural space, adjacent to the source of pain. The electrodes, stimulated by an external or internal source, emit a current that stimulates the pain inhibition pathways.³

The complexity of the procedure demands expertise, a point stressed by Dr Russo.

"It is critically important that spinal cord stimulation is correctly deployed by physicians appropriately trained in its use who employ a multidisciplinary model of care by ensuring that it is combined with appropriate pharmacotherapy and appropriate psychological therapy input to achieve the optimum level of functioning and return to work outcome."

SCS does not eliminate pain but creates paraesthesia resulting in a masking of the pain.³ In order to expand its use and education within the medical arena quality efficacy and costing data are needed.¹

The HTA for SCS covers the health conditions that have been most extensively trialled with the treatment at the time the analysis began in 2007, these include;¹

• Failed back surgery syndrome (FBSS);
• Complex regional pain syndrome (CRPS) type I;
• Ischaemic pain, including critical limb ischaemia (CLI); and
• Refractory angina pectoris.

Assessment of clinical effectiveness

Quality analysis of spinal cord intervention studies identified in the literature for chronic neuropathic or ischaemic pain yielded 11 which were selected for systematic review. Selected studies in each of the health conditions included primary endpoints as follows:¹

• Pain relief;
• Health related quality of life (HRQoL);
• Functional abilities;
• Depression and anxiety;
• Procedure complications; and
• Concomitant medication use.

FBSS

Treatment of failed back surgery syndrome (FBSS) with SCS concomitant with conventional medical management (CMM) was compared to both reoperation and CMM alone. SCS was associated with a greater reduction in pain and opiate use, a greater improvement in functionality and quality of life.¹

CRPS

Physical therapy (PT) was the comparator treatment in the selected complex regional pain syndrome (CRPS) studies. Patients who underwent SCS had a larger perceived global effect than PT patients; furthermore, SCS was more effective in reducing pain in the short term (6 months to 2 years).¹

CLI

SCS reduced the use of analgesics when compared to CMM in critical limb ischaemia (CLI) but this trend did not continue beyond 18 months post implantation. Both treatment arms improved pain relief, limb survival and HRQoL.¹

Refractory angina

There were two separate patient populations recruited into the studies used in the refractory angina assessment; patients that were eligible to receive coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) and patients that were not deemed medically stable enough to undergo these procedures.¹

Compared to no SCS or inactive stimulation in patients that were not medically fit for PCI, frequency of angina attacks were diminished after SCS at 6–8 weeks post implantation. SCS also increased exercise duration, decreased nitrate use and improved HRQoL.¹

Both CABG and SCS yielded similar improvements in cardiovascular function and rate of angina attacks however CABG showed superior improvements in exercise duration and nitrate consumption. Findings suggest that patients who meet medical requirements to undergo PCI and CABG may benefit greater from these procedures whereas for those that cannot, SCS could provide a successful alternative.¹

Complications

Across the board, SCS complications were usually minor and easily treated. 1% of patients needed to have the SCS device removed as a result of infection. Remaining complications included lead migration or fracture, loss of paraesthesia or dural puncture.¹

Assessment of cost effectiveness

One UK based study that compared the cost effectiveness of SCS to available alternative treatments was selected for review. The study assessed cost-effectiveness using standard and internationally recognised methods; determining the incremental cost effectiveness ratio (iCER) and quality-adjusted life year (QALY) produced by the treatment.¹

The QALY is a measure of the number of extra quality years of life the patient experiences as a result of the treatment. In terms of SCS, patient rated pain reduction is the primary indicator used to determine the QALY. The National Institute for Health and Clinical Excellence (NICE) does not advocate a treatment as cost effective for a QALY greater than 20,000–30,000 pounds (approximately 38,000–58,000 AUD). The iCER is a measure of the cost of each extra QALY gained as a result of the test treatment in comparison to the next best alternative.⁴

Improving HRQoL and functionality, while decreasing pain rating and medication use, positively affected the QALY for FBSS patients who underwent SCS. Accordingly, treatment with SCS was presented as a cost effective treatment option. Analysis determined that when the SCS device has longevity of 4 years, the cost for FBSS treatment is below 20,000 pounds per QALY gained. When SCS device longevity was altered in the analysis to greater than 3 years, the iCER for FBSS patients was less than 20,000 pounds per QALY when compared to reoperation, and increased to a maximum of 22,000 pounds when compared to CMM.¹

Treatment with SCS for CRPS patients was found to be cost effective when the SCS device cost does not exceed 6,000 pounds. SCS is a more effective short-term treatment for CRPS and achieves higher patient satisfaction ratings than physical therapy. With SCS device longevity of 4 years, the cost for CRPS treatment is around 25,095 pounds per QALY gained. When device longevity was adjusted to greater than 3 years iCERs were between 10,000 to 66,000 pounds per QALY. While results suggest that SCS is less cost effective for CRPS than FBSS the authors concede that estimating for CRPS is still speculative given the limited data available for systematic review.¹

While SCS was found to be more cost effective for treating refractory angina compared to revascularisation procedures the efficacy results do not indicate that SCS is the superior treatment and therefore the cost effectiveness cannot be determined. The authors maintain that further research is needed with a higher sample number in order to reach a definitive conclusion.¹

Dr Russo said, "Failed back surgery syndrome and complex regional pain syndrome are far more common and therefore there is more data available to prove its efficacy; whereas the efficacy is clear to any given individual pain specialist in regards to the response to refractory angina and critical limb ischaemia, but it is more difficult to recruit published evidence in the literature to document that effect."

Budget impact

Results from the analysis indicated that use of SCS will increase exponentially at 5% growth per annum in the UK.¹

Dr Russo agrees that this growth rate should be similar in Australia. he said:

"Spinal cord stimulators have traditionally been expensive devices but subsequent entry of other device manufacturers in the market place will ultimately drive competition and drive costs down, and the stimulation devices continue to improve over time. 

"It is slowly recognised that early deployment in appropriately selected patients yields not only the best clinical outcome but the most cost-effective outcome. Spinal cord stimulation is currently grossly underutilised for the number of patients with the target condition."

As the number of patients that are treated with SCS increase, the cost per year for the treatment is projected to decrease as a result of the cost savings from the previous year’s interventions. This pattern is expected to continue for 4 years. At 5 years, the assessment predicts the first round of SCS patients will need battery replacement and hence the cost per annum will rise, compensating for these procedures as well as the new SCS patients for that year. An increase in cost in then expected to continue as each year battery replacement surgery will be necessary for a new round of patients.¹

As the evaluation used data from 2007 and the device competition and longevity has expanded vastly since then.¹

Dr Russo said:

"Now we have devices with longevity from 9 up to 15 years. Clearly that will make an enormous difference to the cost-effectiveness ratio."

For more information, see Spinal Cord Stimulation and Spinal Cord Stimulation Devices.

References

1. Simpson EL, Duenas A, Holmes MW, Papaioannou D, Chilcott J. Spinal cord stimulation for chronic pain of neuropathic or ischaemic origin: systematic review and economic evaluation. Health Technology Assessment. 2009; 13 (17).
2. Evidence-based Recommendations for the Pharmacological Management of Neuropathic Pain Position Statement.Australian Pain Society [online]. June 2008 [cited Sept 2009]. Available from: URL: http://www.apsoc.org.au/
3. Bala MM, Riemsma RP, Nixon J, Kleijnen J. Systematic Review of the (Cost-) effectiveness of Spinal Cord Stimulation for People With Failed Back Surgery Syndrome. Clin J Pain. 2008; 24:741-56.
4. NHS: National Institute for Health and Clinical Excellence. Measuring effectiveness and cost effectiveness: the QALY [online]. 2009 [cited Sept 2009]. Available from: URL: http://www.nice.org.uk/