Zits and back pain sharing a common cause? Multiple headlines in the British press proclaiming antibiotics to be a much sought after “magic bullet” for chronic back pain. Could this actually be true?
Probably not is the short answer. The stories were based on research carried out by university hospitals in Denmark on 162 adults who had lower pain due to a slipped disc for more than six months.
To take part in the study, they also had to have disease-related changes in the vertebrae next to the slipped disc site, in the form of bone swelling; so-called Modic type 1 changes, or bone oedema.
The hypothesis put forward by the research team was that, in some cases at least, the bone swelling might be caused by bacterial infection and, therefore, might respond to antibiotic treatment.
The participants were divided into two groups and randomised to receive a 100-day course of a penicillin derivative or 100 days of a placebo. They were assessed using a number of health parameters both before and after the 100-day trial period and again after a year. Here’s what the researchers found:
The group given antibiotics improved their disability and back pain scores after treatment; these improvements were even greater a year after treatment.
A back pain score improved from 15 in the antibiotic group to 11.5 at 100 days and seven at one year. For the placebo group, the score fell from 15 to just 14 at 100 days, with no further change after one year.
Patients reported that pain relief and improvement in disability started gradually: for most of them, this occurred six to eight weeks after starting antibiotic tablets, and for some at the end of the treatment period.
Many participants reported feeling better for at least another six months after the antibiotics were stopped – and some people reported continuing improvement at a one-year follow-up.
Based on repeat MRI scans, fewer disease-related changes were detected in the vertebrae of the spine in patients given antibiotics than those given a placebo.
Side effects were more common in the antibiotic group (65 per cent) compared with the placebo group (23 per cent).
Meanwhile in a related paper, the Danish team examined degenerated lumbar discs that had been removed from patients with low pain.
They found a bacteria called Proprionibacterium acne was present in these diseased discs. This is the same bug that causes zits – as the name suggests, it is one of the causes of infected spots in acne patients.
Taken together, the research suggests a role for infection and antibiotics in certain people with back pain. But it is far from definitive proof that Propionibacterium acne is a cause of such pain, even in a select group.
Which is why headlines such as “Breakthrough could eliminate need for major operations” and talk of Nobel prizes for the authors are completely over the top. But nor should the research be dismissed out of hand.
Many of us still remember the scorn, and in some cases the ridicule, endured by Australian gastroenterologists Barry Marshall and Robin Warren when they postulated an infective cause for duodenal ulcers.
They were eventually proved right when they showed beyond doubt that ulcers were linked to the presence in the stomach of the Helicobacter pylori microb e.
What is needed is more research on a much larger and more diverse pool of patients.
The assessment period for improvement will need to extend longer than
a year. And while the Danish research was "blinded" – participants did not know if they were taking an antibiotic or an inert pill – it is possible that the greater side effects experienced by the antibiotic group may have
subconsciously influenced how they reported their symptoms.
A suitably calm conclusion is that the research represents a potentially exciting breakthrough for about a third of patients with chronic low back pain.
mhouston@irishtimes.com
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