MD, PhD, FMedSci, FSB, FRCP, FRCPEd

meta-analysis

A meta-analysis compared the effectiveness of spinal manipulation therapies (SMT), medical management, physical therapies, and exercise for acute and chronic low back pain. Studies were chosen based on inclusion in prior evidence syntheses. Effect sizes were converted to standardized mean effect sizes and probabilities of recovery. Nested model comparisons isolated non-specific from treatment effects. Aggregate data were tested for evidential support as compared to shams.

The results suggest that, of 84% acute pain variance, 81% was from non-specific factors and 3% from treatment. No treatment was better than sham. Most acute results were within 95% confidence bands of that predicted by natural history alone. For chronic pain, 66% out of 98% was non-specific, but treatments influenced 32% of outcomes. Chronic pain treatments also fitted within 95% confidence bands as predicted by natural history. The evidential support for treating chronic back pain as compared to sham groups was weak, but chronic pain appeared to respond to SMT, while whole systems of chiropractic management did not.

The authors of this intriguing paper conclude: Meta-analyses can extract comparative effectiveness information from existing literature. The relatively small portion of outcomes attributable to treatment explains why past research results fail to converge on stable estimates. The probability of treatment superiority between treatment arms was equivalent to that expected by random selection. Treatments serve to motivate, reassure, and calibrate patient expectations – features that might reduce medicalization and augment self-care. Exercise with authoritative support is an effective strategy for acute and chronic low back pain.

This essentially indicates that none of these treatments for low back pain are convincingly effective. In turn this means we might as well stop using them. Alternatively, we could opt for the therapy that carries the least risks and cost. As the authors point out, this treatment is exercise.

Is acupuncture an effective treatment for pain? This is a question which has attracted decades of debate and controversy. Proponents usually argue that it is supported by good clinical evidence, millennia of tradition and a sound understanding of the mechanisms involved. Sceptics, however, tend to be unimpressed and point out that the clinical evidence of proponents often is cherry-picked, that a long history of usage is fairly meaningless, and that the alleged mechanisms are tentative at best.

This discrepancy of opinions is confusing, particularly for lay people who might be tempted to try acupuncture. But it might vanish in the light of a new, comprehensive and unique evaluation of the clinical evidence.

An international team of acupuncture trialists published a meta-analysed of individual patient data to determine the analgesic effect of acupuncture compared to sham or non-acupuncture control for the following 4 chronic pain conditions: back and neck pain, osteoarthritis, headache, and shoulder pain. Data from 29 RCTs, with an impressive total of 17 922 patients, were included.

The results of this new evaluation suggest that acupuncture is superior to both sham and no-acupuncture controls for each of these conditions. Patients receiving acupuncture had less pain, with scores that were 0.23 (95% CI, 0.13-0.33), 0.16 (95% CI, 0.07-0.25), and 0.15 (95% CI, 0.07-0.24) SDs lower than those of sham controls for back and neck pain, osteoarthritis, and chronic headache, respectively; the effect sizes in comparison to no-acupuncture controls were 0.55 (95% CI, 0.51-0.58), 0.57 (95% CI, 0.50-0.64), and 0.42 (95% CI, 0.37-0.46) SDs.

Based on these findings, the authors reached the conclusion that “acupuncture is effective for the treatment of chronic pain and is therefore a reasonable referral option. Significant differences between true and sham acupuncture indicate that acupuncture is more than a placebo. However, these differences are relatively modest, suggesting that factors in addition to the specific effects of needling are important contributors to the therapeutic effects of acupuncture”.

Only hours after its publication, this new meta-analysis was celebrated by believers in acupuncture as the strongest evidence yet on the topic currently available. Much of the lay press followed in the same, disappointingly uncritical vein.The authors of the meta-analysis, most of whom are known enthusiasts of acupuncture, seem entirely sure that they have provided the most compelling proof to date for the effectiveness of acupuncture. But are they correct or are they perhaps the victims of their own devotion to this therapy?

Perhaps, a more sceptical view would be helpful – after all, even the enthusiastic authors of this article admit that, when compared to sham, the effect size of real acupuncture is too small to be clinically relevant. Therefore one might argue that this meta-analysis confirms what critics have suggested all along: acupuncture is not a useful treatment for clinical routine.

Unsurprisingly, the authors of the meta-analysis do their very best to play down this aspect. They reason that, for clinical routine, the comparison between acupuncture and non-acupuncture controls is more relevant than the one between acupuncture and sham. But this comparison, of course, includes placebo- and other non-specific effects masquerading as effects of acupuncture – and with this little trick ( which, by the way is very popular in alternative medicine), we can, of course, show that even sugar pills are effective.

I do not doubt that context effects are important in patient care; yet I do doubt that we need a placebo treatment for generating such benefit in our patients. If we administer treatments which are effective beyond placebo with kindness, time, compassion and empathy, our patients will benefit from both specific and non-specific effects. In other words, purely generating non-specific effects with acupuncture is far from optimal and certainly not in the interest of our patients. In my view, it cannot be regarded as not good medicine, and the authors’ conclusion referring to a “reasonable referral option” is more than a little surprising in my view.

Acupuncture-fans might argue that, at the very minimum, the new meta-analysis does demonstrate acupuncture to be statistically significantly better than a placebo. Yet I am not convinced that this notion holds water: the small residual effect-size in the comparison of acupuncture with sham might not be the result of a specific effect of acupuncture; it could be (and most likely is) due to residual bias in the analysed studies.

The meta-analysis is strongly driven by the large German trials which, for good reasons, were heavily and frequently criticised when first published. One of the most important potential drawbacks was that many participating patients were almost certainly de-blinded through the significant media coverage of the study while it was being conducted. Moreover, in none of these trials was the therapist blinded (the often-voiced notion that therapist-blinding is impossible is demonstrably false). Thus it is likely that patient-unblinding and the absence of therapist-blinding importantly influenced the clinical outcome of these trials thus generating false positive findings. As the German studies constitute by far the largest volume of patients in the meta-analysis, any of their flaws would strongly impact on the overall result of the meta-analysis.

So, has this new meta-analysis finally solved the decades-old question about the effectiveness of acupuncture? It might not have solved it, but we have certainly moved closer to a solution, particularly if we employ our faculties of critical thinking. In my view, this meta-analysis is the most compelling evidence yet to demonstrate the ineffectiveness of acupuncture for chronic pain.

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