The idea of “adjusting” the spine refers to many different manual therapies that wiggle, pop, and otherwise manipulate spinal joints. This is “spinal manipulative therapy” or SMT, one of the most famous of all hands-on therapies and the defining feature of chiropractic therapy (although it is offered by many other healthcare professionals, especially physical therapists). Although expert opinions on SMT range widely, the use of SMT for acute back pain specifically has long been regarded even by many critics as the closest thing to an evidence-based treatment in alternative health care, chiropractic’s crown jewel.
A major new review of SMT has been published in , pooling the results of 26 studies of SMT for fresh cases of back pain (less than six weeks). Fifteen of those studies provided “moderate-quality evidence” of “clinically modest” effects on pain, roughly 10% relief in the short term, “the same as the benefit for nonsteroidal anti-inflammatory drugs in acute low back pain.” (The remaining studies did not provide any supporting evidence, for various reasons.)
Weirdly, this review has been loudly touted by SMT providers as good news, which it isn’t. 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). So the abstract sounds like good news to all but the most wary reader, while deep in the main text the same results are finally conceded to be “clinically modest,” and even that seems excessively generous: personally, I need a 20% improvement to consider it “modest”!
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 map, and it can’t be explained by any obvious, measurable factor, which 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 can have more potent benefits in some cases.
Far from being positive, this review continues a strong trend of damning SMT with faint praise, and adds evidence of backfiring. 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 a 10% 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.
I’ve now cited and discussed this paper in both my low back pain book and full discussion of spinal manipulative therapy.
Importance: Acute low back pain is common and spinal manipulative therapy (SMT) is a treatment option. Randomized clinical trials (RCTs) and meta-analyses have reported different conclusions about the effectiveness of SMT. Objective: To systematically review studies of the effectiveness and harms of SMT for acute (≤6 weeks) low back pain. Data Sources: Search of MEDLINE, Cochrane Database of Systematic Reviews, EMBASE, and Current Nursing and Allied Health Literature from January 1, 2011, through February 6, 2017, as well as identified systematic reviews and RCTs, for RCTs of adults with low back pain treated in ambulatory settings with SMT compared with sham or alternative treatments, and that measured pain or function outcomes for up to 6 weeks. Observational studies were included to assess harms. Data Extraction and Synthesis: Data extraction was done in duplicate. Study quality was assessed using the Cochrane Back and Neck (CBN) Risk of Bias tool. This tool has 11 items in the following domains: randomization, concealment, baseline differences, blinding (patient), blinding (care provider [care provider is a specific quality metric used by the CBN Risk of Bias tool]), blinding (outcome), co-interventions, compliance, dropouts, timing, and intention to treat. Prior research has shown the CBN Risk of Bias tool identifies studies at an increased risk of bias using a threshold of 5 or 6 as a summary score. The evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. Main Outcomes and Measures: 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. Findings: 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.Conclusions and Relevance: 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.