Addit: Two placebo studies using spinal cord stimulation (SCS) were brought to my attention by an attendee at a neuromodulation conference I was speaking at a few days ago. None of the proponents of SCS included these papers in their talks and the spine study was not included in the systematic review I refer to in my previous blog. And read on, I found a third placebo study.A study from 2017 (Kriek, 2017) used five different ‘modes’ of stimulation (different frequencies and patterns) and placebo allocated at random for two weeks each over a ten week period in patients with chronic regional pain syndrome. The placebo group did worse. Interestingly, there was little difference between all the other modes (except burst therapy did worse), and the difference to placebo was pretty close to the difference that most people would consider ‘clinically important’. This gives us some evidence for spinal cord stimulation, but I would have liked to have seen if the patients were truly blinded. This ‘old’ technology relies on the patient being able to feel it, and the authors didn’t report on the success of blinding. I also would have liked to have seen a bigger difference, and authors that were not paid by the manufacturer, including a professional medical writer who wrote the article (no serious academic would ever agree to this).
In 2014, researchers published a study (Schu, 2014)randomising 20 patients with ‘failed back surgery syndrome’ to different modes of SCS and placebo, each over a three week period. This one did not rely on the patient feeling the stimulation so blinding was probably better, and this was for spine pain, not chronic regional pain syndrome. Also, although some authors were paid by the manufacturer and the study was funded by the manufacturer, the study was conducted independently. The study didn’t show a big (or significant) difference between placebo and higher frequency stimulation for pain or disability but it did show that ‘burst’ frequencies did much better than the other groups.
So we have some mixed evidence, with burst therapy either being the best or the worst of the modes of therapy, and no difference between higher frequency stimulation and placebo for failed back surgery syndrome.
But while researching these articles, I came across the study I had always wanted to do: in a study from 2013 (Perruchoud, 2013) newer (high frequency) SCS was compared to sham in a group of 40 patients, who each received both, but were blinded as to which one they got. It was funded by the manufacturer but they weren’t involved in design, data collection or writing. This study showed no difference between SCS and sham for any outcome. That doesn’t surprise me, what does surprise me is that I have been asking the SCS community to do a trial like this for ages and no one has ever mentioned it or apparently even been aware of it. I checked the systematic review again from my previous post and it WAS listed in there, as a low quality study in which patients were not blinded, which is not true (but explains why I didn’t look it up). What the hell is going on here? In other fields where placebo trials have been done not everyone agrees with the results, but EVERYONE is at least aware of the studies!
The bottom line
These trials are enough evidence that SCS doesn’t work (particularly on the back of the much lauded study that high frequency – which is no better than placebo in 2/2 trials – is superior to conventional). If people want SCS funded, they should step up and produce studies like these that show an effect. The problem is, it already is funded.