Despite being prescribed fairly commonly, a new study has found that antidepressants provide little to no benefit when it comes to relieving low back pain and sciatica. More research is needed into the long-term benefits and harms of using antidepressants in this way.
Antidepressants are prescribed for low back pain (LBP), most commonly when other treatments have failed. However, there is little consensus about what class of antidepressant works best, so international guidelines are often conflicting.
In a new study, researchers from Neuroscience Research Australia (NeuRA) and the University of New South Wales (UNSW) reviewed existing research to assess the benefits and harms of using particular classes of antidepressants to treat non-specific LBP and spine-related leg pain or sciatica.
“Low back pain has been the leading cause of disability worldwide for the past 30 years,” said lead and corresponding author Michael Ferraro, a doctoral candidate at the Center for Pain IMPACT, NeuRA, and the School of Health Sciences, UNSW. “Many people with low back pain also have pain that radiates down their leg, often leading to greater pain and disability. Antidepressants are commonly prescribed for low back pain and sciatica, despite conflicting recommendations from international clinical guidelines.”
The researchers examined data from 2,932 people across 26 randomized controlled trials that included participants with non-specific LBP (18 studies), spine-related leg pain (seven studies), or both conditions (one study). Most participants, whose mean age ranged from 27 to 59, had chronic pain lasting more than three months. The studies investigated serotonin and norepinephrine reuptake inhibitors (SNRIs, eight studies), selective serotonin reuptake inhibitors (SSRIs, two studies), tricyclic antidepressants (TCAs, 14 studies), tetracyclic antidepressants (TeCAs, two studies), or ‘other antidepressants’ (two studies). All of the studies were placebo-controlled.
Antidepressants and what they do (in very simple terms)
SNRIs – Elevate mood by increasing levels of the ‘feel good’ chemical serotonin and the ‘fight-or-flight’ chemical norepinephrine. Includes duloxetine (Cymbalta), venlafaxine (Effexor).
SSRIs – Increase serotonin levels, mainly to help with depression and anxiety. Includes fluoxetine (Prozac), sertraline (Zoloft), escitalopram (Lexapro).
TCAs – Also increase serotonin and norepinephrine but tend to produce more side-effects. Sometimes prescribed for chronic pain. Includes amitriptyline (Endep) and nortriptyline (Pamelor).
TeCAs – Use a slightly different mechanism to TCAs to boost serotonin and norepinephrine. Often sedating. Includes mirtazapine (Remeron).
“We found that serotonin and norepinephrine reuptake inhibitor medicines probably reduce pain within three to four months, but on average, the effects are probably too small to be important and many patients wouldn’t be able to feel any difference in their pain compared to taking a sugar pill,” Ferraro said. “They also come with an increased risk of unwanted side effects.”
The researchers also found that TCAs probably provided a small improvement in function but were unlikely to reduce pain intensity in those with LBP. The researchers’ confidence in the evidence about SNRIs and TCAs was only moderate because not all of the studies they reviewed provided the data they needed. They had little to no confidence in the evidence relating to the efficacy of the other antidepressants, including as a treatment for sciatica.
“Unfortunately, the available research does not tell us much about the effects of antidepressants on sciatica, despite their common use,” said Ferraro. “Large, high-quality clinical trials of serotonin and norepinephrine reuptake inhibitors and tricyclic antidepressants are urgently needed to inform treatment of sciatica.
“We need more research on antidepressants for back pain and sciatica, especially to understand their longer-term effects, including those that might arise once treatment has stopped.”
Ferraro says that, of course, people with LBP are open to try these medications, but they should be properly informed about what they should expect before doing so.
“Some patients may still choose to trial these medications, but informed discussions about the likely magnitude of benefit and possible risks are crucial,” he said. “It’s also important to stress, these findings do not imply that severely depressed people with low back pain and sciatica should not be treated with antidepressants.”
The study is available from the Cochrane Database of Systematic Reviews (CDSR), part of the Cochrane Library. A Cochrane review is a systematic review that identifies, evaluates, and integrates evidence about a specific research question.
Source: NeuRA