Acupuncture for elbow pain
Bandolier
is always attracted to systematic reviews claiming to find strong evidence
about a treatment effect. Strong evidence is not easy to find, but one expects
a rock on which good practice can be built. When strong evidence and
acupuncture are used in the same sentence, though,
Bandolier
begins to smell a rat. Not because of any bias, but because good evidence
indicates that acupuncture does not work.
It
should be an educational experience, then, to see how a review of acupuncture
for elbow pain [1] stacks up against the requirements of quality, validity, and
size (QVS). What does this mean?
- Quality: trials that are randomised and double blind, to avoid selection and observer bias, and where we know what happened to most of the subjects in the trial.
- Validity: trials that mimic clinical practice, or could be used in clinical practice, and with outcomes that make sense. For instance, in chronic disorders we want long-term, not short-term trials. We are not interested in small changes of marginal statistical significance (p < 0.05, say, or a 1 in 20 chance of being wrong), but changes that are large, useful, and statistically very significant (p < 0.01, a 1 in 100 chance of being wrong).
- Size: trials (or collections of trials) with large numbers of patients avoid being wrong because of the random play of chance. For instance, to be sure that a number needed to treat (NNT) of 2.5 is really between 2 and 3, we need results from about 500 patients. If that NNT is above 5, we need data from thousands of patients.
These
are the criteria on which we should judge evidence. For it to be strong
evidence, it has to meet all three criteria.
The review
The
review sought randomised studies of patients with pain resulting from tennis
elbow, with other descriptions, but essentially with pain originating from the
common origin of the extensor tendon, and with needle acupuncture as the
primary intervention. Excluded were other elbow problems, and patients
concurrently receiving other treatments.
Results
Of
53 articles screened, the authors chose to include six. Results from all these
six trials were combined in a qualitative 'best evidence synthesis'.
Of
these six included trials, one was not properly randomised.
Of
the remaining five trials, two were not double blind.
Of
the remaining three, one had results only immediately after treatment (not much
use in a chronic condition, and duration of the condition was about 10 months
in some of the trials).
That
left two randomised, double-blind trials, both of which reported results two or
three months after treatment. Both compared real acupuncture with sham
acupuncture (using different needle points, for instance). Both reported
outcomes roughly equivalent to half pain relief, and the rates were similar
(Figure 1).
Figure 1: Valid, randomised trials of acupuncture versus sham acupuncture for tennis elbow
There
was no significant difference between real and sham acupuncture. The relative
benefit was 1.2 (0.96 to 1.6).
Comment
This
review failed QVS criteria. Six original trials soon became two small and
useful trials, with valid outcomes, but no different from control. Even if
there were an effect, it is so small that we would need large trials to be
confident that it was there: our information is from only 123 patients.
And
that is the best one might say. Reading the original trials is interesting. One
included trial was published twice (without acknowledging the other), quoted
odds ratios to six significant figures (52.2888 seemed slightly over-precise
based on 48 patients), and used NNTs when results were not statistically
significant. That does not give much confidence in the quality of trial
reporting.
So
is there strong evidence for acupuncture in tennis elbow? No. Actually there is
no evidence that it works, and what evidence we have suggests it does not work
in any meaningful way. A pity, then, that this will be seized upon as a way of
extracting money from wallets.
Reference:
- KV Trinh et al. Acupuncture for the alleviation of lateral epicondyle pain: a review. Rheumatology 2004 (advance access 22 June, doi: 10.1093/rheumatology/keh247).
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