A study of spinal cord stimulators for injured workers with chronic low back and leg pain
Description
Spinal cord stimulators (SCS) for injured workers with chronic low back and leg pain after lumbar surgery - A prospective pilot study to describe costs, complications, and patient outcomes. This study features a non-randomized prospective study of spinal cord stimulation (SCS) for Workers' Compensation claimants with chronic low back and leg pain despite previous lumbar spine surgery. The main purpose is to determine the proportion of Workers Compensation claimants with chronic low back and leg pain (LBP) despite previous spine surgery who show improvement one year and two years after Spinal Cord Stimulator (SCS) implantation.
If you have any questions, please email scsniams@u.washington.edu or call the Study Coordinator at (800) 283-5303.
Principal Investigator
William Hollingworth, Ph.D
Research Assistant Professor, Radiology
Harborview Injury Prevention Center
Research Questions
1. To determine the proportion of Workers Compensation claimants with chronic low back and leg pain (LBP) despite previous spine surgery who show improvement (defined as 50% or greater leg pain reduction and 2 point or greater reduction in the Roland Scale of back pain-related physical disability and less than daily narcotic analgesic use) one year and two years after Spinal Cord Stimulator (SCS) implantation.
2. To compare these outcomes to those of other claimants with chronic LBP and prior spine surgery who receive: a) usual care; or b) multi-disciplinary pain clinic treatment.
3. To estimate the per-patient direct cost of medical care and time loss compensation (wage replacement payments for lost work time) to the Department of Labor and Industries (DLI) over a period of 18 months in the SCS and comparison groups.
4. To describe the types of complications and adverse events associated with SCS, and their prevalence, in the first 18 months after SCS implantation in a group of DLI claimants with chronic LBP and prior spine surgery.
RESEARCH METHODS
Study Design:
We propose a non-randomized prospective study of spinal cord stimulation (SCS) for Workers’ Compensation claimants with chronic low back and leg pain despite previous lumbar spine surgery. The SCS intervention group will be prospectively recruited and compared to two comparison groups. The first comparison group (C1) will comprise Workers’ Compensation patients with chronic LBP who meet inclusion and exclusion criteria for SCS (described below), but who have not been offered SCS by their physician. This group will be prospectively identified from DLI administrative databases and will receive usual care for their symptoms. The second comparison group (C2) will be prospectively identified on an ongoing basis as requests are made for authorization for treatment at a multi-disciplinary pain clinic. The inclusion and exclusion criteria for each group are described below.
Inclusion criteria:
• Patient has an open, compensable Washington State Workers Compensation state fund claim for a back injury and is receiving time loss compensation (SCS, C1, C2)
• Low back pain radiating into one or both legs for more than 6 months (SCS, C1, C2)
• Radicular pain greater than axial pain (SCS, C1, C2)
• Patient has undergone one, two, or three open lumbar spine surgeries within the past 3 years (SCS, C1, C2)
• Average leg pain in the last month rated as greater than 5 on a (0-10) numerical rating scale (SCS, C1, C2)
• Patient is able and willing to use the SCS (SCS)
• Patient understands the limits and risks of the therapy (SCS)
Exclusion criteria:
• Age < 18 years (SCS, C1, C2)
• Age > 60 years (SCS, C1, C2)
• Claim covered by self-insured employer (SCS, C1, C2)
• Prior SCS trial or implantation (SCS, C1, C2)
• Diabetes (SCS, C1, C2)
• More than 3 prior open lumbar spine surgeries
• Progressive motor deficit (SCS)
• Progressive bony deformity (SCS)
• Coontraindiction for surgery (SCS)
• Inability to complete interviews in English or Spanish (SCS, C1, C2)
• Patient does not have access to a telephone (SCS, C1, C2)
• Patient does not consent to participate in the study (SCS, C1, C2)
• These criteria are included in order to target SCS therapy at the group of patients most likely to benefit. We will review these criteria after 3 months of enrollment and, if necessary, relax these criteria to enhance patient enrollment.
Research HighlightsPrevious work by our group on this topic:
1: Spinal cord stimulation for patients with failed back surgery syndrome or complex regional pain syndrome: a systematic review of effectiveness and complications.
Turner JA, Loeser JD, Deyo RA, Sanders SB.
Pain. 2004 Mar;108(1-2):137-47. Review. PMID: 15109517 [PubMed - indexed for MEDLINE]
Description: We conducted a systematic review of the literature on the effectiveness of spinal cord stimulation (SCS) in relieving pain and improving functioning for patients with failed back surgery syndrome and complex regional pain syndrome (CRPS). We also reviewed SCS complications. Literature searches yielded 583 articles, of which seven met the inclusion criteria for the review of SCS effectiveness, and 15 others met the criteria only for the review of SCS complications. Two authors independently extracted data from each article, and then resolved discrepancies by discussion.
Conclusion: We identified only one randomized trial, which found that physical therapy (PT) plus SCS, compared with PT alone, had a statistically significant but clinically modest effect at 6 and 12 months in relieving pain among patients with CRPS. Similarly, six other studies of much lower methodological quality suggest mild to moderate improvement in pain with SCS. Pain relief with SCS appears to decrease over time. The one randomized trial suggested no benefits of SCS in improving patient functioning. Although life-threatening complications with SCS are rare, other adverse events are frequent. On average, 34% of patients who received a stimulator had an adverse occurrence. We conclude with suggestions for methodologically stronger studies to provide more definitive data regarding the effectiveness of SCS in relieving pain and improving functioning, short- and long-term, among patients with chronic pain syndromes.
Table1
Table1 shows (in order of publication date), for each study included in the complications review, the number of patients assessed for complications and their diagnoses, dates stimulators implanted, mean length of follow-up, and percent of patients with one or more complications. With a few exceptions, sample sizes were small. Lengths of follow-up and reported complication rates were highly variable.
2: Spinal cord stimulation for chronic low back pain: a systematic literature synthesis
Turner JA, Loeser JD, Bell KG.
Spinal Neurosurgery. 1995 Dec;37(6):1088-95; discussion 1095-6. PMID: 8584149 [PubMed - indexed for MEDLINE]
Description: A systematic literature synthesis was performed to analyze the long-term risks and benefits of spinal cord stimulation for patients with failed back surgery syndrome. Relevant articles were identified through a MEDLINE search (January 1966-June 1994), bibliography reviews, searches of personal files, and literature supplied by a stimulator manufacturer. Two investigators independently reviewed each article to determine whether it met the following study inclusion criteria: 1) original data on return to work, pain, medication use, reoperations, functional disability, or stimulator use after permanent implantation of spinal cord stimulators in patients with chronic low back or leg pain despite previous back surgery; and 2) follow-up > or = 30 days for all patients. Articles were excluded if data from patients with other diagnoses were mixed with (and could not be separated from) data from patients with chronic low back or leg pain, or if their data were redundant with those reported in an included article. Articles written in languages other than English or French were excluded.
Conclusion: Thirty-nine studies, all case studies, were analyzed. At follow-up (mean, 16 mo; range, 1-45 mo), an average of 59% of patients had > or = 50% pain relief (range, 15-100% of patients). Complications occurred in 42% of patients but were generally minor. It seems that approximately 50 to 60% of patients with failed back surgery syndrome report > 50% pain relief with the use of spinal cord stimulation at follow-up; the lack of randomized trials precludes conclusions concerning the effectiveness of spinal cord stimulation relative to other treatments, placebo, or no treatment.
Questionaires and Follow-Up:
The UW research assistant will contact patients in the SCS and comparison groups by telephone at baseline, and at 6, 12 and 24 months. We will collect information on:
1) Age (Baseline)
2) Gender (Baseline)
3) Ethnicity / race (Baseline)
4) Marital status (Baseline)
5) Education (Baseline)
6) Number of previous lumbar surgeries (Baseline)
7) Back pain numerical rating scale (0-10) average pain intensity in past month (Baseline,6,12,24)
8) Leg pain numerical rating scale (0-10) average pain intensity in past month (Baseline,6,12,24)
9) Roland back-related function (Baseline,6,12,24)
10) Work status (Baseline,6,12,24)
11) Mental Health (Baseline,12,24)
12) Compensation status (Workers comp / SSDI) (Baseline,6,12,24)
13) Worker-perceived change in pain and function compared to baseline interview date (12,24)
14) Use of analgesics (Baseline,6,12,24)
15) Complications (requiring an office visit, outpatient visit or hospitalization) (SCS group only 6,12,18,24) – from telephone interviews, medical billing data, and medical charts
16) Resource utilization and time loss (12,18) – from DLI medical bills data
Primary outcome:
The composite primary outcome will be the proportion of patients who achieve 50% or greater reduction (relative to baseline) in leg pain AND less than daily narcotic medication use AND a 2 point or greater improvement on the Roland function scale. The 12-month follow-up will be the primary outcome, but this composite outcome will also be calculated at 24-months.
Secondary outcomes:
Secondary outcomes will be baseline to follow-up change in leg pain, back pain, physical disability (Roland), depressive symptom severity; cumulative number of time loss days; compensation status at follow-up (on or off time loss); medical costs in the 18 months after the baseline interview; time loss compensation costs in the 18 months after the baseline interview; self-reported work status at follow-up; self-reported symptom satisfaction at follow-up; and self-reported change in pain and function at one year and two years. We will also examine complications in the SCS group.