People over 65 are being prescribed antidepressants to treat pain despite weak evidence that the drugs work, potentially exposing them to harm, according to a new study that calls for a review of prescribing guidelines.
Researchers led by Dr Sujita Narayan from the University of Sydney’s Institute for Musculoskeletal Health reviewed the findings from 15 trials involving 1,369 participants to assess how antidepressants impact pain relief and adverse events in older adults.
Based on these studies, Narayan told Guardian Australia there were many international guidelines that recommend the use of antidepressants for pain, “particularly for chronic pain”.
“Antidepressants are now being used more for pain than for depression in older people. We wanted to understand what evidence there is in terms of the benefits and impact of antidepressant use for pain relief in this population.”
But the researchers found a lack of evidence to support the use of antidepressants for treating most pain conditions in older adults.
Most of the trials they examined had small sample sizes of fewer than 100 participants making it difficult to generalise any findings about the drugs improving pain, and researchers involved in many of the trials had conflicts of interests including links to pharmaceutical companies that produce pain relief drugs, potentially biasing the results.
The research, published in the British Journal of Clinical Pharmacology on Friday, found limited evidence to support the use of antidepressants such as duloxetine for managing pain related to knee osteoarthritis, but even then the effect was small and there was an increased risk of side-effects.
The study authors recognised that pain may lead to depression and that antidepressants may be used by some doctors to address both conditions, but said the benefit when used primarily for pain relief was small and inconsistent.
Benefits of prescribing need to be weighed up against the risk of side-effects, with the study finding older people taking antidepressants experienced negative side-effects such as falling, feeling dizzy and getting injured.
Narayan said many of the studies examining use of antidepressants to treat pain also involved younger participants, but people aged over 65 may have health conditions that make antidepressant use riskier.
There may also be harmful side-effects when trying to stop antidepressant medication, the study said, and there were growing concerns about the difficulties people face when coming off the medications.
“There should be a review of the existing guidelines, particularly for older people, because there is very little evidence to support the use of antidepressants for pain,” Narayan said. “The evidence is that it causes more harms than benefits in most of this population.”
She urged people to talk to their doctor before ceasing any medication, and cautioned that antidepressant medication needs to be stopped extremely carefully under medical supervision to minimise risks of side-effects.
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A senior specialist in geriatric medicine, Prof Joseph Ibrahim, said it could be complex to assess and treat pain conditions in older people because chronic pain can lead to feelings of depression and anxiety.
Doctors needed to weigh up the cause of those conditions, alongside the impact of other conditions the person may have, and assess possible drug interactions, risks and side-effects, he said.
Ibrahim said older people often felt their pain and feelings of despair related to it were dismissed or ignored, and that this could lead to under-treatment.
“It’s a real juggle,” he said.
A clinical research fellow with the National Health Service in London who has researched the prescription of and side-effects from antidepressants, Dr Mark Horowitz, described Narayan’s paper as “very useful”. He said antidepressants had no long-term efficacy for treatment of chronic pain for adults of any age.
He said the drugs were overprescribed generally. “High and increasing rates of antidepressant prescribing among older adults is becoming a major concern in Australia,” he said.
“Sixty per cent of older adults in aged care facilities are now prescribed antidepressants. We know in this age group that these drugs are associated with an increase in the risk of falls, fractures, strokes and an early death, as well as bleeding risks, osteoperosis, cataracts and some with an increased risk of dementia.”