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Do antidepressants help for treatment of back pain and osteoarthritis?
A study examining the efficacy and safety of this line of medicine compared with placebo indicates otherwise.
Antidepressants are either ineffective or provide a minimal relief for back pain, a new study highlights.
Both antidepressants and analgesics are two of the most commonly prescribed medications in Australia.
In 2016, an estimated one in five people aged 45 and over were living with persistent, ongoing pain. Meanwhile, GPs have seen a 67% rise in patient encounters for chronic pain over the past 10 years.
When first-line pain medications such as paracetamol and ibuprofen fail to improve symptoms, many patients are prescribed antidepressants for their pain.
Longstanding evidence points to the role of antidepressants in treating pain such as back pain, headache, arthritis and osteoporosis.
However, new research from the University of Sydney says otherwise.
Published in the BMJ, the study concludes that antidepressants offer ‘little to no help’ for people experiencing chronic back pain and osteoarthritis – and may even cause harm.
‘The use of antidepressants to treat people with chronic back pain and osteoarthritis is increasing worldwide, but prior to our work, it was not clear whether antidepressants relieved pain or were safe,’ lead author Dr Giovanni Ferreira said.
‘We … found that for back pain antidepressants were either ineffective or provided a very small effect, which was unlikely to be perceived as worthwhile by most patients.
‘For people with osteoarthritis, effects were still small, but could be potentially perceived as worthwhile by some patients.’
The authors conducted a systematic review and meta-analysis that included 33 randomised controlled trials on 5318 participants with low back or neck pain, sciatica, or hip or knee osteoarthritis.
They then compared the efficacy or safety, or both, of any antidepressant drug with placebo by treating participants with drugs for their pain condition – not depression in those living with pain.
Six classes of drugs were used, including serotonin-noradrenaline reuptake inhibitors (SNRIs) and tricyclic antidepressants.
The study set a difference of 10 points on a 0–100 scale for pain as the smallest worthwhile difference between groups, a common threshold in studies of chronic pain.
Key findings for the individual areas of pain showed that:
- SNRIs had a minor effect on reducing back pain by 5.3 points out of 100 on the pain scale, compared with placebo after three months
- for osteoarthritis pain, SNRIs had a slightly stronger effect after three months, with an average difference of 9.7 points on the pain scale, compared with placebo
- the authors note that although this amount is small, it comes close to the 10-point difference needed for antidepressants to be considered worthwhile by some patients
- tricyclic antidepressants were ineffective for back pain and related disability.
SNRIs were also found to significantly increase the risk of patients experiencing an adverse event – about two-thirds of patients taking this class of antidepressant had at least one adverse event such as nausea.
‘[These results are] concerning, as some antidepressants significantly increase the risk of a person to experience adverse events,’ Dr Ferreira said.
‘Many people are being treated with these medications that may not be helping their pain and may be doing them harm.’
Co-author Professor Andrew McLachlan also warned of the potential adverse effects of abruptly ceasing antidepressant treatment for back pain and osteoarthritis.
‘This can lead to withdrawal effects which can be distressing and sometimes present as serious health issues,’ he said.
‘These withdrawal effects include dizziness, nausea, anxiety, agitation, tremor, sweating, confusion and sleep disturbance.’
Given the study findings that the effect of SNRIs on pain and disability scores is small and not clinically important for back pain – but a clinically important effect cannot be excluded for osteoarthritis – the authors anticipate their findings could assist in more informed decisions about whether to treat chronic back pain and osteoarthritis pain with antidepressants.
‘More research is needed to resolve uncertainties about the efficacy of antidepressants for sciatica and osteoarthritis highlighted by this review,’ Dr Ferreira said.
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