Neurostimulation

1. Neurostimulation For Failed Back Surgery Syndrome Literature Review Summary

2. The most common use of SCS in the United States is for controlling the pain associated with failed back surgery syndrome (FBSS). FBSS occurs in patients who have typically undergone multiple lumbosacral spine operations for conditions such as disk herniation, lumbar stenosis, or spinal instability.1,2,3,4 The majority of patients with FBSS have radicular pain in one or both legs, and many patients also have axial lower back pain.2 This literature review summary highlights results of studies to demonstrate the clinical and cost-effectiveness of SCS for FBSS. Background

3. Effectiveness StudyKumar K, et al. 20071 Prospective, randomized, controlled multicenter study of 100 FBSS patients randomized to conventional medical management (CMM) with or without SCS. At 6 months, 48% (24/50) of SCS patients and 9% (4/43) of CMM patients achieved the primary outcome of ≥ 50% leg pain relief. SCS group had significantly greater health-related quality of life (HRQoL) (P < 0.02) (Figure 1) and functional capacity (P < 0.001) (Figure 2). At 12 months, as-treated analysis found that 48% of SCS patients and 18% of CMM patients achieved ≥ 50% leg pain relief (P = 0.03). Figure 1 Figure 2

4. Effectiveness StudyNorth RB, et al. 20055 Prospective, randomized, controlled study of 50 FBSS patients who had been selected for repeat lumbosacral spine surgery. Patients were randomized to SCS or re-operation. At a mean follow-up of 2.9 years, 47% of SCS patients and 12% of re-operation patients reported ≥ 50% pain relief and satisfaction with treatment (P < 0.01). Use of narcotics was significantly less in SCS patients, in that use was stable or decreased in 87% compared to 58% in re-operation patients (P < 0.025).

5. Effectiveness StudiesKumar K, et al. 20066 and Leveque J-C, et al. 20016 Retrospective study of 410 SCS patients, of which 220 were FBSS patients. At a mean follow-up period of 97.6 months, 60% (132/184) of implanted patients had ≥ 50% pain relief.2 Retrospective study of 30 FBSS patients; 16 had permanent SCS system implantation. At a median follow-up of 34 months, 75% (12/16) of implanted patients said that they were continuing to experience ≥ 50% pain relief.6

6. Effectiveness StudiesDario A, et al. 20017 and Ohnmeiss DD, et al. 20018 Prospective study of 49 FBSS patients, of which 24 were SCS candidates. At a mean follow-up of 42 months, 91% (21/23) of implanted patients continued to have “good results.”7 Retrospective study of 41 consecutive SCS candidates with chronic, intractable low back pain (mainly FBSS). At follow-up, which ranged from 5.5 to 19 months, 70% (21/36) of implanted patients said they were satisfied with SCS outcome, 76% said they would have SCS again, and 79% said they would recommend SCS to someone else.8

7. Additional Effectiveness Studies

8. Cost StudyNorth RB, et al. 200713 Hospital and professional charge data (1991-1995 US$) on 40/50 patients in the randomized trial of the effectiveness of SCS vs. re-operation.5 Mean cost per patient for intention to treat (ITT) was $31,530 for SCS and $38,160 for re-operation. SCS was more dominant (more effective and less expensive) than re-operation in incremental cost-effectiveness and cost-utility ratios. Intention-to-Treat Cost-effectiveness Plane This ITT bootstrap simulation for incremental costs and QALYs shows that 59% of results fall in the lower right-hand plane. This finding demonstrates that SCS is more effective and less costly compared to re-operation. Further, approximately 72% of results fall below the cost-effectiveness threshold ($40,000) routinely used by US health policy makers.

9. Cost StudyTaylor RJ, et al. 200514 Decision-analytic and Markov model to assess SCS for FBSS relative to conventional medical management (CMM).* The 2-year base case cost for SCS was 16,250€ vs. 13,248€ for CMM, giving an incremental cost of 3,002€ for SCS. Incremental utility for SCS was 0.066 QALYs per patient. The lifetime base cost for an average patient was 75,758€ for SCS vs. 122,725€ for CMM, giving an incremental cost of 46,967€ for CMM. Incremental utility for SCS was 1.12 QALYs per patient. * Based on economic study of SCS for FBSS by Kumar, et al. Health care costs were converted from Canadian dollars at year 2000 prices to Euros at Year 2003 prices, based on both purchasing parity and health care cost inflation in the European Union. Costs were discounted at 6%.

10. Additional Cost StudiesKumar K, et al. 200615 and Kumar K, et al. 200216 and Bell GK., et al. 199717 Calculated actual health care costs (2005 Canadian$) for SCS and its complications in 160 consecutive patients. Mean cost of SCS implant was $23,205 with $3,609 in maintenance costs per year for an uncomplicated case.15 Calculated actual 5-year health care costs (2000 Canadian$) for 60 FBSS patients with SCS matched to 44 with CMM. Mean 5-year cost for SCS was $29,123 per patient vs. $38,029 per patient for CMM. SCS was cost-effective after 2.5 years.16 5-year health care cost model (1994 US$) for two identical FBSS patients, one with SCS and one with back surgery. 5-year cost for SCS was $80,000 on a charges basis vs. $82,630 for surgery. For the patient who passes the SCS trial and for whom SCS is effective, SCS pays for itself within 2.1 years.17

11. Summary In all referenced clinical studies,1-3,5-12 including two RCTs, SCS was effective in controlling the pain of FBSS long-term. SCS has been associated with substantial reduction in medication3,5,10,11 and significant increases in activities of daily living.1,7,11 Five studiesfound that SCS enabled return to work for an average of 27% of patients (range 22-36%).3,7,10-12 The most frequent complication of SCS has been electrode migration (2-18%).1,10-12 Electrode breakage from earlier studies9-12 did not occur in later studies.1,3,6,8 In five studies, 6-15% of patients developed infection.6-7,10-12 Various complications have also led to surgical revision of pulse generator, lead and/or system explantation. Cost studies showed that mean first-year cost becomes substantially less in the second year.

12. Conclusions The long-term clinical studies that are summarized have shown that SCS is effective in controlling pain associated with FBSS, providing ≥ 50% relief in 48-91% of the patients among these studies. Two economic studies indicated that as compared to CMM, SCS should become cost-effective after about 2 years.16,17

13. Neurostimulation Therapy for Chronic PainTruck and/or Limbs: Product manuals must be reviewed prior to use for detailed disclosure. Indications: Implantable neurostimulation systems: A Medtronic implantable neurostimulation system is indicated for spinal cord stimulation (SCS) system as an aid in the management of chronic, intractable pain of the trunk and/or limbs—including unilateral or bilateral pain associated with the following conditions: Failed Back Syndrome (FBS) or low back syndrome or failed back, radicular pain syndrome or radiculopathies resulting in pain secondary to FBS or herniated disk, postlaminectomy pain, multiple back operations, unsuccessful disk surgery, degenerative Disk Disease (DDD)/herniated disk pain refractory to conservative and surgical interventions, peripheral causalgia, epidural fibrosis, arachnoiditis or lumbar adhesive arachnoiditis, Complex Regional Pain Syndrome (CRPS), Reflex Sympathetic Dystrophy (RSD), or causalgia. Contraindications: Diathermy: Do not use shortwave diathermy, microwave or therapeutic ultrasound diathermy (all now referred to as diathermy) on patients implanted with a neurostimulation system. Energy from diathermy can be transferred through the implanted system and cause tissue damage at the locations of the implanted electrodes, resulting in severe injury or death. Warnings: Sources of strong electromagnetic interference (e.g., defibrillation, diathermy, electrocautery, MRI, RF ablation, and therapeutic ultrasound) can interact with the neurostimulation system, resulting in serious patient injury or death. These and other sources of EMI can also result in system damage, operational changes to the neurostimulator or unexpected changes in stimulation. Rupture or piercing of the neurostimulator can result in severe burns. An implanted cardiac device (e.g., pacemaker, defibrillator) may damage a neurostimulator, and the electrical pulses from the neurostimulator may result in an inappropriate response of the cardiac device. Precautions: The safety and effectiveness of this therapy has not been established for pediatric use (patients under the age of 18), pregnancy, unborn fetus, or delivery. Patients should be detoxified from narcotics prior to lead placement. Clinicians and patients should follow programming guidelines and precautions provided in product manuals. Patients should avoid activities that may put undue stress on the implanted neurostimulation system components. Patients should not scuba dive below 10 meters of water or enter hyperbaric chambers above 2.0 atmosphere absolute (ATA). Electromagnetic interference, postural changes, and other activities may cause shocking or jolting. Adverse Events: Adverse events may include undesirable change in stimulation described by some patients as uncomfortable, jolting or shocking; hematoma, epidural hemorrhage, paralysis, seroma, CSF leakage, infection, erosion, allergic response, hardware malfunction or migration, pain at implant site, loss of pain relief, chest wall stimulation, and surgical risks. For further information, please call Medtronic at 1-800-328-0810 and/or consult Medtronic’s website at www.medtronic.com. Rx only

14. References • Kumar K, Taylor R, Jacques L, et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicentre randomized controlled trial in patients with failed back surgery syndrome. Pain. 2007;132(1-2):179-188. • Kumar K, Hunter G, Demeria D. Spinal cord stimulation in treatment of chronic benign pain: challenges in treatment planning and present status, a 22-year experience. Neurosurgery. 2006;58:481-496. • Devulder J, De Laat M, Van Bastelaere M, Rolly G. Spinal cord stimulation: a valuable treatment for chronic failed back surgery patients. J Pain Symptom Manage. 1997;13:296-301. • Heidecke V, Rainov NG, Burket W. Hardware failures in spinal cord stimulation for failed back surgery syndrome. Neuromodulation. 2000;3:27-30. • North RB, Kidd DH, Farrokhi F, Piantadosi SA. Spinal cord stimulation versus repeated lumbosacral spine surgery for chronic pain; a randomized, controlled trial. Neurosurgery. 2005;56:98-107. • Leveque J-C, Villavicencio AT, Bulsara KR, et al. Spinal cord stimulation for failed lower back surgery syndrome. Neuromodulation. 2001;4:1-9. • Dario A, Fortini G, Bertollo D, et al. Treatment of failed back surgery syndrome. Neuromodulation. 2001;4:105-110. • Ohnmeiss DD, Rashbaum RF. Patient satisfaction with spinal cord stimulation for predominant complaints of chronic, intractable low back pain. Spine J. 2001;1:358-363. • Rainov NG, Heidecke V, Burkert W. Short test-period spinal cord stimulation for failed back surgery syndrome. Minim Invasive Neurosurg. 1996;39:41-44. • Fiume D, Sherkat S, Callovini GM, et al. Treatment of failed back syndrome due to lumbo-sacral epidural fibrosis. Acta Neurochir. 1995(Suppl);64:116-118. • De La Porte C,Van de Kelft E. Spinal cord stimulation in failed back surgery syndrome. Pain. 1993;52:55-61. • North RB, Ewend MG, Lawton MT, et al. Failed back surgery syndrome: 5-year follow-up after spinal cord stimulator implantation. Neurosurgery. 1991;28:692-699. • North RB, Kidd D, Shipley J, et al. Spinal cord stimulation versus reoperation for failed back surgery syndrome: a cost-effectiveness and cost utility analysis based on a randomized, controlled trial. Neurosurgery. 2007;61:361-369. • Taylor RJ, Taylor, RS. Spinal cord stimulation for failed back surgery syndrome: a decision-analytic model and cost-effective analysis. Int J Technol Assess Health Care. 2005;21:351-358. • Kumar K, Wilson JR, Taylor RS, Gupta S. Complications of spinal cord stimulation, suggestions to improve outcome, and financial impact. J Neurosurg Spine. 2006;5:19-203. • Kumar K, Malik S, Demeria D, et al. Treatment of chronic pain with spinal cord stimulation versus alternative therapies: cost-effectiveness analysis. Neurosurgery. 2002;51:106-116. • Bell GK, Kidd D, North RB. Cost-effective analysis of spinal cord stimulation in treatment of failed back surgery syndrome. J Pain Symptom Manage. 1997;13:28-295.

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