Researchers cast doubt on use of antidepressants for back pain and osteoarthritis

This is despite them being recommended in most clinical practice guidelines for long-term back pain, and also for hip and knee osteoarthritis.

The researchers analysed published data from 33 randomised controlled trials in which more than 5,000 adults with low back or neck pain, sciatica, or hip or knee osteoarthritis took part.

Any gains 'not worthwhile' 

Based on ‘moderate certainty evidence’, the researchers conclude that prescribing antidepressants for people with back pain leads to an effect that is too small to be worthwhile – while not ruling out a small beneficial effect for osteoarthritis.

The researchers set a difference of 10 points on a 0-100-point scale for pain or disability as denoting the smallest worthwhile difference between groups – a threshold commonly used in other studies of chronic pain.

The results showed that serotonin-norepinephrine reuptake inhibitors (SNRIs) reduced back pain after three months. But the effect was small – an average difference of 5.3 points on a pain scale compared with placebo. For most patients, this would not be considered as a clinically important benefit, the authors suggest.

Osteoarthritis

Turning to osteoarthritis, they found a slightly stronger effect of SNRIs on pain after three months – an average difference of 9.7 points on the pain scale compared with placebo, meaning that a worthwhile effect could not be excluded.

‘Low certainty’ evidence showed that tricyclic antidepressants were ineffective for back pain and related disability. 

Large, definitive randomised trials that are free of industry ties are urgently needed to resolve uncertainties about the efficacy of antidepressants for sciatica and osteoarthritis [Giovanni Ferreira and colleagues]

Though the researchers acknowledge their study had some limitations, they say it updates the evidence for back pain, sciatica and osteoarthritis, and could help clinicians and their patients decide whether to take antidepressants for chronic pain.

'Large, definitive randomised trials that are free of industry ties are urgently needed to resolve uncertainties about the efficacy of antidepressants for sciatica and osteoarthritis highlighted by this review,' they conclude. 

Efficacy and safety of antidepressants for the treatment of back pain and osteoarthritis; sytematic review and meta analysis  https://www.bmj.com/content/372/bmj.m4825

Linked editorial

In a linked editorial, Martin Underwood, a professor at Warwick Medical School, and colleague Colin Tysall say a consistent approach on using antidepressants to treat people with painful disorders is needed.

The authors acknowledge that some patients might opt to take antidepressants if they offered even a small and worthwhile chance of reducing their pain after three months.

‘Overall, however, drug treatments are largely ineffective for back pain and osteoarthritis and have the potential for serious harm.

‘We need to work harder to help people with these disorders to live better with their pain without recourse to the prescription pad,’ the authors conclude.

Antidepressants for musculoskeletal pain https://www.bmj.com/content/372/bmj.n80