The question whether spinal manipulative therapy (SMT) is effective for acute low back pain is still discussed controversially. Chiropractors (they use SMT more regularly than other professionals) try everything to make us believe it does work, while the evidence is far less certain. Therefore, it is worth considering the best and most up-to-date data.
The aim of this paper was to systematically review studies of the effectiveness and harms of SMT for acute (≤6 weeks) low back pain. The research question was straight forward: Is the use of SMT in the management of acute (≤6 weeks) low back pain associated with improvements in pain or function?
A through literature search was conducted to locate all relevant papers. Study quality was assessed using the Cochrane Back and Neck (CBN) Risk of Bias tool. The evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. The main outcome measures were pain (measured by either the 100-mm visual analog scale, 11-point numeric rating scale, or other numeric pain scale), function (measured by the 24-point Roland Morris Disability Questionnaire or Oswestry Disability Index [range, 0-100]), or any harms measured within 6 weeks.
Of 26 eligible RCTs identified, 15 RCTs (1711 patients) provided moderate-quality evidence that SMT has a statistically significant association with improvements in pain (pooled mean improvement in the 100-mm visual analog pain scale, −9.95 [95% CI, −15.6 to −4.3]). Twelve RCTs (1381 patients) produced moderate-quality evidence that SMT has a statistically significant association with improvements in function (pooled mean effect size, −0.39 [95% CI, −0.71 to −0.07]). Heterogeneity was not explained by type of clinician performing SMT, type of manipulation, study quality, or whether SMT was given alone or as part of a package of therapies. No RCT reported any serious adverse event. Minor transient adverse events such as increased pain, muscle stiffness, and headache were reported 50% to 67% of the time in large case series of patients treated with SMT.
The authors concluded that among patients with acute low back pain, spinal manipulative therapy was associated with modest improvements in pain and function at up to 6 weeks, with transient minor musculoskeletal harms. However, heterogeneity in study results was large.
This meta-analysis has been celebrated by chiropractors around the world as a triumph for their hallmark therapy, SMT. But there have also been more cautionary voices – not least from the lead author of the paper. Patients undergoing spinal manipulation experienced a decline of 1 point in their pain rating, says Dr. Paul Shekelle, an internist with the West Los Angeles Veterans Affairs Medical Center and the Rand Corporation who headed the study. That’s about the same amount of pain relief as from NSAIDs, over-the-counter nonsteroidal anti-inflammatory medication, such as ibuprofen. The study also found spinal manipulation modestly improved function. On average, patients reported greater ease and comfort engaging in two day-to-day activities — such as finding they could walk more quickly, were having less difficulty turning over in bed or were sleeping more soundly.
It’s not clear exactly how spinal manipulation relieves back pain. But it may reposition the small joints in the spine in a way that causes less pain, according to Dr. Richard Deyo, an internist and professor of evidence-based medicine at the Oregon Health and Science University. Deyo wrote an editorial published along with the study. Another possibility, Deyo says, is that spinal manipulation may restore some material in the disk between the vertebrae, or it may simply relax muscles, which could be important. There may also be mind-body interaction that comes from the “laying of hands” or a trusting relationship between patients and their health care provider, he says.
Deyo notes that there are many possible treatments for lower back pain, including oral medicine, injected medicine, corsets, traction, surgery, acupuncture and massage therapy. But of about 200 treatment options, “no single treatment is clearly superior,” he says.
In another comment by Paul Ingraham the critical tone was much clearer: “Claiming it as a victory is one of the best examples I’ve ever seen of making lemonade out of science lemons! But I can understand the mistake, because the review itself does seem positive at first glance: the benefits of SMT are disingenuously summarized as “statistically significant” in the abstract, with no mention of clinical significance (effect size; see Statistical Significance Abuse). So the abstract sounds like good news to anyone but the most wary readers, while deep in the main text the same results are eventually conceded to be “clinically modest.” But even even that seems excessively generous: personally, I need at least a 2-point improvement in pain on a scale of 10 to consider it a “modest” improvement! This is not a clearly positive review: it shows weak evidence of minor efficacy, based on “significant unexplained heterogeneity” in the results. That is, the results were all over the place — but without any impressive benefits reported by any study — and the mixture can’t be explained by any obvious, measurable factor. This probably means there’s just a lot of noise in the data, too many things that are at least as influential as the treatment itself. Or — more optimistically — it could mean that SMT is “just” disappointingly mediocre on average, but might have more potent benefits in a minority of cases (that no one seems to be able to reliably identify). Far from being good news, this review continues a strong trend (eg Rubinstein 2012) of damning SMT with faint praise, and also adds evidence of backfiring to mix. Although fortunately “no RCT reported any serious adverse event,” it seems that minor harms were legion: “increased pain, muscle stiffness, and headache were reported 50% to 67% of the time in large case series of patients treated with SMT.” That’s a lot of undesirable outcomes. So the average patient has a roughly fifty-fifty chance of up to roughly maybe a 20% improvement… or feeling worse to some unknown degree! That does not sound like a good deal to me. It certainly doesn’t sound like good medicine.”
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As I have made clear in many previous posts, I do fully agree with these latter statements and would add just three points:
- We know that many of the SMT studies completely neglect reporting adverse effects. Therefore it is hardly surprising that no serious complications were on record. Yet, we know that they do occur with sad regularity.
- None of the studies controlled for placebo effects. It is therefore possible – I would say even likely – that a large chunk of the observed benefit is not due to SMT per se but to a placebo response.
- It seems more than questionable whether the benefits of SMT outweigh its risks.