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The greatest hits of back pain science are a disappointment

PainSci » bibliography » Machado et al 2009
Tags: treatment, classics, scientific medicine, manual therapy, back pain, pain problems, spine

Nine articles on PainSci cite Machado 2009: 1. Deep Friction Massage Therapy for Tendinitis2. Complete Guide to Low Back Pain3. Are Orthotics Worth It?4. Microbreaking5. Healer Syndrome6. Does Spinal Manipulation Work?7. Pseudo-Quackery in the Treatment of Pain8. Science versus Experience in Musculoskeletal Medicine9. “Windows of Opportunity” in Rehab

PainSci summary of Machado 2009: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

This is a meticulous, sensible, and readable analysis of the very best studies of back pain treatments that have ever been done: the greatest hits of back pain science. There is a great deal of back pain science to review, but authors Machado, Kamper, Herbert, Maher and McCauley found that shockingly little of it was worth their while: just 34 acceptable studies out of a 1031 candidates, and even among those “trial quality was highly variable.” Their conclusions are derived from only the best sort of scientific experiments: not just the gold-standard of randomized and placebo-controlled tests, but carefully choosing only the “right” kind of placebos (several kinds of placebos were grounds for disqualification, because of their known potential to skew the results). They do a good job of explaining exactly how and why they picked the studies they did, and pre-emptively defending it from a couple common concerns. The results were sad and predictable, robust evidence of absence: “The average effects of treatments … are not much greater than those of placebos.”

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

OBJECTIVE: Estimates of treatment effects reported in placebo-controlled randomized trials are less subject to bias than those estimates provided by other study designs. The objective of this meta-analysis was to estimate the analgesic effects of treatments for non-specific low back pain reported in placebo-controlled randomized trials.

METHODS: Medline, Embase, Cinahl, PsychInfo and Cochrane Central Register of Controlled Trials databases were searched for eligible trials from earliest records to November 2006. Continuous pain outcomes were converted to a common 0-100 scale and pooled using a random effects model.

RESULTS: A total of 76 trials reporting on 34 treatments were included. Fifty percent of the investigated treatments had statistically significant effects, but for most the effects were small or moderate: 47% had point estimates of effects of <10 points on the 100-point scale, 38% had point estimates from 10 to 20 points and 15% had point estimates of>20 points. Treatments reported to have large effects >20 points) had been investigated only in a single trial.

CONCLUSIONS: This meta-analysis revealed that the analgesic effects of many treatments for non-specific low back pain are small and that they do not differ in populations with acute or chronic symptoms.

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