medwireNews: Serotonin–noradrenaline reuptake inhibitors (SNRIs) may reduce pain for up to 3 months in people with osteoarthritis (OA), but it is unclear whether the effect is clinically relevant, show the results of a meta-analysis published in The BMJ.
The analysis by Giovanni Ferreira (University of Sydney, New South Wales, Australia) and colleagues included data from 33 randomized controlled trials (n=5318 participants) comparing the efficacy and/or safety of antidepressant drugs with that of placebo in people with hip or knee OA, low back or neck pain, or sciatica.
Of these, eight trials evaluated SNRIs in 1941 people with knee osteoarthritis. None of the eight trials included people with hip OA, none evaluated other classes of antidepressant, and none had a duration of more than 3 months.
Ferreira and team report that there was moderate certainty evidence to suggest that, compared with placebo, SNRIs reduce OA pain by a significant 4.66 points on average during the first 2 weeks of treatment when assessed on a scale of 0 to 100.
There was also low certainty evidence showing that OA pain was reduced by a significant mean 9.72 points versus placebo at 3–13 weeks, and although this difference fell below the clinically important threshold of 10.00 points, the researchers note that “the lower limit of the confidence interval did contain clinically important effects for pain.”
“Therefore, a clinically important benefit of SNRI in people with osteoarthritis cannot be excluded,” they say.
For disability, SNRIs were associated with a significant mean 5.10-point reduction versus placebo in the first 2 weeks and a significant mean 6.07-point reduction in weeks 3 to 13, with moderate and low certainty evidence, respectively.
The authors also point out that six out of eight OA trials were sponsored by industry.
For people with back pain, there was moderate certainty evidence that SNRIs reduce pain and disability up to 3 months, but the effects were below the threshold for clinical relevance. There was also low to very low certainty evidence that SNRIs and tricyclic antidepressants might be clinically effective for sciatica.
Safety was assessed in 13 trials (n=3447 participants), which together gave low certainty evidence that SNRIs increase the risk for any adverse event versus placebo by a significant 23%, with rates of 62.5% and 49.7%, respectively. There was no significant difference between the two groups in the risk for serious adverse events, however.
Ferreira and co-authors conclude: “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.”
In an accompanying editorial, Martin Underwood and Colin Tysall, both from the University of Warwick in Coventry, UK, say the data show that overall “drug treatments are largely ineffective for back pain and osteoarthritis and have the potential for serious harm.”
They add: “We need to work harder to help people with these disorders to live better with their pain without recourse to the prescription pad.”
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