This week many in the medical profession have taken to social media to express surprise (and some a degree of alarm) at the publication of a study on the efficacy of an antibiotic, Amoxicillin, as a treatment for chronic low back pain.
The results of the “double blind, randomised, placebo controlled, multicentre trial” are published in the latest edition of the British Medical Journal. Its stated objective was to “assess the efficacy of three months of antibiotic treatment compared with placebo in patients with chronic low back pain, previous disc herniation, and vertebral endplate changes (Modic changes).”
The authors’ conclusion, which did not seem to surprise the majority of commentators, was:
“In this study on patients with chronic low back pain and Modic changes at the level of a previous disc herniation, three months of treatment with amoxicillin did not provide a clinically important benefit compared with placebo. Secondary analyses and sensitivity analyses supported this finding. Therefore, our results do not support the use of antibiotic treatment for chronic low back pain and Modic changes.”
The following comments on Twitter were typical:
“Amoxicillin for 3 months showed no benefit in chronic lower back pain. What’s more surprising than that is that this study was even done, and is in @BMJ_latest.”
“And people wonder how antibiotic resistance occurs.”
“What the hell? Makes no sense why this was done.”
However, some were supportive of the need for this research. Referencing an earlier study in 2013, one wrote:
“There have been studies that have suggested antibiotic therapy could help with back pain. They were controversial and this study has significant value in challenging previous publications.”
Chronic low back pain is not the only pain condition in respect of which there is published medical literature chronicling what appears to be a beneficial effect on pain and other symptoms after taking an antibiotic. Back in 2017, we reported on a Canadian paper which describes a single observed instance where a patient who was prescribed a broad-spectrum antibiotic, Cefadroxil, for a minor infection, experienced an improvement in the CRPS in her left upper limb. Her CRPS had otherwise appeared resistant to therapy and her left hand had become clawed.
She reported that within days of commencing the antibiotic she experienced a reduction in her pain and allodynia, reduced clenching of her fingers and thumb, improved voluntary movement in her arm and a lessening of her fatigue.
Within 12 hours of completing the 10-day course, her symptoms reverted to their former level. Those treating her made a decision to carry out a short trial of alternating weeks on and off the Cefadroxil and monitored what happened. Within 2 to 3 days of recommencing the antibiotic, her pain and motor function again improved.
The patient opted to continue on Cefadroxil with apparently ongoing benefit to her CRPS, but with unpleasant side-effects from the antibiotic.
What should we make of this?
Clearly, there is no escaping the fact that there are a few studies which are supportive of a link between antibiotics and an improvement in chronic pain. However, extreme caution is required.
One theory is that a proportion of cases of chronic low back pain are the result of bacterial infection. If correct, that could explain why antibiotics seemed to prove effective in a few cases, ie those recipient had been suffering a very specific type of low back pain.
As far as CRPS is concerned, the big red flag here is that the paper documents one isolated case. Clearly, each year many people suffering CRPS are prescribed broad-spectrum antibiotics to treat infections. From a lay perspective, it would seem likely that if even a small proportion of those people experienced an improvement in their symptoms, the possible link would occur to at least some of them, who would quite rightly be shouting about that. In other words, there would be a reasonable amount of anecdotal evidence – which does not appear to be there.
That is not to say that the lady who was the subject of the study was not experiencing an improvement in her CRPS symptoms, simply that in her case, currently nobody can explain the mechanism behind it.
A bigger problem
Of course, if antibiotics were proven to be of benefit for chronic pain, another issue arises. As we said in our earlier article:
“With the next new superbug always around the corner, many fear that the war against bacterial infection may be all but lost. As we know, persuading our family doctor to prescribe antibiotics is now nigh on impossible; a rearguard action in the battle against antibiotic resistance. Medical procedures such as surgery and chemotherapy may become impossible if this battle is lost and we are again facing the possibility that in just a few years a chest infection or even a simple cut may prove life threatening.”
With that in mind, if it were proven that antibiotics were beneficial for chronic pain of any kind, licensing authorities would face a huge dilemma.