Cochrane Corner: Spinal cord stimulation for chronic back pain

Marco Steiner, a 55-year-old construction worker, had a serious fall on a building site three years ago, resulting in a fracture of the 5th lumbar vertebra. As a result, Mr. Steiner had to be operated on promptly. Despite intensive rehabilitation, he continued to experience chronic back pain with pain radiating into the leg. Considerable pain-related restrictions remained. Treatment with stronger analgesics, including morphine derivatives and tricyclic antidepressants failed to sufficiently alleviate the pain. Conservative measures such as acupuncture and transcutaneous electrical nerve stimulation (TENS) were also not effective. After two attempts at returning to work, it was clear that Mr. Steiner would not be able to return to the construction site he was subsequently assessed as unfit for work.

In an effort to intensify the treatment, the pain therapist submitted an application to the accident insurance company requesting the coverage of costs for epidural spinal cord stimulation (SCS). The insurance physician planned an evaluation of the evidence on the effectiveness of spinal cord stimulation using evidence-based guidelines, systematic reviews and, if these were lacking, primary studies. In addition to pain reduction, the search also included studies evaluating patient-relevant outcomes such as functionality, quality of life, maintenance of social activities, and the ability to maintain or regain work (1).

In this situation, a group of scientists examined the available scientific evidence with a Cochrane Review (2). The review analyzed thirteen randomized controlled trials with 699 participants and compared the treatment of low back pain with spinal cord stimulation versus placebo treatment or no treatment. The observation period was between 3 and 12 months. In order for pain studies to deliver reliable results, certain methods must be built into the design, e.g., blinding of doctors, patients, as well as the specialists who assess the treatment outcome. These methods are intended to protect against the suggestive effect of expectations of pain relief. In addition, compliance with further methodological standards is assessed, e.g., consideration of all patients in the results or the use of appropriate statistical methods in cross-over studies. The appropriate use of such methods establishes the trustworthiness of the results.
After testing, the researchers came to the conclusion that spinal cord stimulation for the treatment of lumbar spine pain was no more effective than a placebo and would probably result in little to no pain relief for patients and no improvement in their functionality or quality of life (3). Based on the methods used to protect against spurious conclusions, the authors assessed the reliability of the results as moderate (on a four-point scale: high - moderate - low - very low). This assessment suggests that the result is close to the true treatment effect. The comparison of spinal cord stimulation plus conservative (non-invasive) treatment versus conservative treatment alone yielded similar results: here too, spinal cord stimulation resulted in little or no clinically relevant improvement in back pain, pain radiating into the leg, functionality, or health-related quality of life. The methods used in the study design to protect against false conclusions were so inadequate that the reliability of the results was rated as low to very low. The studies provided insufficient information regarding risks, side effects, and possible harm to patients.