A new update of the current Cochrane review assessed the benefits and harms of spinal manipulative therapy (SMT) for the treatment of chronic low back pain. The authors included all randomised controlled trials (RCTs) examining the effect of spinal manipulation or mobilisation in adults (≥18 years) with chronic low back pain with or without referred pain. Studies that exclusively examined sciatica were excluded.
The effect of SMT was compared with recommended therapies, non-recommended therapies, sham (placebo) SMT, and SMT as an adjuvant therapy. Main outcomes were pain and back specific functional status, examined as mean differences and standardised mean differences (SMD), respectively. Outcomes were examined at 1, 6, and 12 months.
Forty-seven RCTs including a total of 9211 participants were identified. Most trials compared SMT with recommended therapies. In 16 RCTs, the therapists were chiropractors, in 14 they were physiotherapists, and in 5 they were osteopaths. They used high velocity manipulations in 18 RCTs, low velocity manipulations in 12 studies and a combination of the two in 20 trials.
Moderate quality evidence suggested that SMT has similar effects to other recommended therapies for short term pain relief and a small, clinically better improvement in function. High quality evidence suggested that, compared with non-recommended therapies, SMT results in small, not clinically better effects for short term pain relief and small to moderate clinically better improvement in function.
In general, these results were similar for the intermediate and long term outcomes as were the effects of SMT as an adjuvant therapy.
Low quality evidence suggested that SMT does not result in a statistically better effect than sham SMT at one month. Additionally, very low quality evidence suggested that SMT does not result in a statistically better effect than sham SMT at six and 12 months. Low quality evidence suggested that SMT results in a moderate to strong statistically significant and clinically better effect than sham SMT at one month. Additionally, very low quality evidence suggested that SMT does not result in a statistically significant better effect than sham SMT at six and 12 months.
(Mean difference in reduction of pain at 1, 3, 6, and 12 months (0-100; 0=no pain, 100 maximum pain) for spinal manipulative therapy (SMT) versus recommended therapies in review of the effects of SMT for chronic low back pain. Pooled mean differences calculated by DerSimonian-Laird random effects model.)
About half of the studies examined adverse and serious adverse events, but in most of these it was unclear how and whether these events were registered systematically. Most of the observed adverse events were musculoskeletal related, transient in nature, and of mild to moderate severity. One study with a low risk of selection bias and powered to examine risk (n=183) found no increased risk of an adverse event or duration of the event compared with sham SMT. In one study, the Data Safety Monitoring Board judged one serious adverse event to be possibly related to SMT.
The authors concluded that SMT produces similar effects to recommended therapies for chronic low back pain, whereas SMT seems to be better than non-recommended interventions for improvement in function in the short term. Clinicians should inform their patients of the potential risks of adverse events associated with SMT.
This paper is currently being celebrated (mostly) by chiropractors who think that it vindicates their treatments as being both effective and safe. However, I am not sure that this is entirely true. Here are a few reasons for my scepticism:
- SMT is as good as other recommended treatments for back problems – this may be so but, as no good treatment for back pain has yet been found, this really means is that SMT is as BAD as other recommended therapies.
- If we have a handful of equally good/bad treatments, it stand to reason that we must use other criteria to identify the one that is best suited – criteria like safety and cost. If we do that, it becomes very clear that SMT cannot be named as the treatment of choice.
- Less than half the RCTs reported adverse effects. This means that these studies were violating ethical standards of publication. I do not see how we can trust such deeply flawed trials.
- Any adverse effects of SMT were minor, restricted to the short term and mainly centred on musculoskeletal effects such as soreness and stiffness – this is how some naïve chiro-promoters already comment on the findings of this review. In view of the fact that more than half the studies ‘forgot’ to report adverse events and that two serious adverse events did occur, this is a misleading and potentially dangerous statement and a good example how, in the world of chiropractic, research is often mistaken for marketing.
- Less than half of the studies (45% (n=21/47)) used both an adequate sequence generation and an adequate allocation procedure.
- Only 5 studies (10% (n=5/47)) attempted to blind patients to the assigned intervention by providing a sham treatment, while in one study it was unclear.
- Only about half of the studies (57% (n=27/47)) provided an adequate overview of withdrawals or drop-outs and kept these to a minimum.
- Crucially, this review produced no good evidence to show that SMT has effects beyond placebo. This means the modest effects emerging from some trials can be explained by being due to placebo.
- The lead author of this review (SMR), a chiropractor, does not seem to be free of important conflicts of interest: SMR received personal grants from the European Chiropractors’ Union (ECU), the European Centre for Chiropractic Research Excellence (ECCRE), the Belgian Chiropractic Association (BVC) and the Netherlands Chiropractic Association (NCA) for his position at the Vrije Universiteit Amsterdam. He also received funding for a research project on chiropractic care for the elderly from the European Centre for Chiropractic Research and Excellence (ECCRE).
- The second author (AdeZ) who also is a chiropractor received a grant from the European Chiropractors’ Union (ECU), for an independent study on the effects of SMT.
After carefully considering the new review, my conclusion is the same as stated often before: SMT is not supported by convincing evidence for back (or other) problems and does not qualify as the treatment of choice.