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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
The drugs gabapentin and pregabalin (gabapentinoids) were found not to help lower back pain that had lasted more than three months. Gabapentin gave no benefit compared with placebo, while pregabalin was less effective than other painkillers. Both were associated with several side effects, such as dizziness.
Long-term low back pain without clear cause is very common. It causes considerable loss of productivity and places a high demand on the healthcare service. It is difficult to treat, and people often get limited relief from simple painkillers, causing practitioners to consider alternative options.
This review gathered eight trials looking at gabapentinoids for adults with long-term lower back pain. The evidence was very low quality, but overall, supports NICE guidance not to use these drugs to treat long-term lower back pain.
Larger, high-quality studies may provide further insight, particularly regarding their value when there is associated sciatica as gabapentinoids may help some types of nerve pain.
Why was this study needed?
Lower back pain is a common problem experienced by up to eight out of 10 people in the UK at some point in their lives. It can be very debilitating and affect the ability to carry out daily activities including work. Lower back pain is termed long-term when it has lasted for over three months. Often no clear cause can be found, particularly when there is no sciatica (leg pain suggesting direct pressure on a nerve) and finding a suitable treatment can be difficult.
For long-term low back pain, simple painkillers can be ineffective, and there is a move against prescribing stronger opioid-based pain-relief. Gabapentinoids are a group of antiepileptic drugs for the treatment of nerve pain that have been suggested as options for chronic lower back pain, though the evidence for this use is uncertain.
NHS Digital figures show NHS primary care prescriptions of pregabalin have increased more than ten-fold, from less than half a million in 2006 to just over 5.5 million in 2016. Gabapentin prescriptions have also risen from just over one million to 6.5 million over the same period. The commonest indication for this is neuropathic pain - in line with NICE guidance in 2013 (updated in 2017) which suggests a gabapentinoid as first-line treatment.
It is important to know whether they are effective for long-term lower back pain and whether there are any associated harms.
What did this study do?
This systematic review included eight randomised controlled trials assessing the effects of gabapentinoids in adults with chronic lower back pain.
Three trials compared gabapentin with placebo, three compared pregabalin with other drugs, and two looked at using pregabalin alongside other drugs.
Most studies were small and based in a single centre. None came from the UK. Chronic lower back pain had lasted for between one and 18 years, and treatment duration ranged from three to 14 weeks. Pain relief was measured on numerous scales. Evidence was judged to be low to very low quality for most outcomes.
Though trials of chronic lower back pain with or without leg pain were reportedly eligible, the researchers excluded trials in people with predominant leg pain or nerve compression. Only three trials questioned nerve pain specifically.
What did it find?
- Gabapentin provided a non-significant improvement in pain compared to placebo. The standardised mean difference (SMD) was 0.22 units (95% confidence interval [CI] -0.5 to +0.07) on a patient-reported scale of 0 to 10, where lower numbers indicate less pain (three studies, 185 participants).
- Pregabalin was less effective at reducing pain than the other medications. The SMD was 0.42, which is a moderate effect in favour of the other drugs (95% CI 0.20 to 0.64). This was from a meta-analysis of three studies (332 participants), one of which compared pregabalin with an antidepressant class drug (amitriptyline), one a type of anti-inflammatory (celecoxib) and one paracetamol combined with an opioid (Tramacet).
- There was no benefit when pregabalin was given alongside the opioids tapentadol (SMD -0.04, 95% CI -0.26 to +0.18; one study, 306 participants) or buprenorphrine (SMD -0.42, 95% CI -1.02 to +0.17; one study, 44 participants). There was a small benefit when pregabalin was combined with celecoxib compared with celecoxib alone (SMD -0.81, 95% -1.29 to -0.33; one study, 72 participants).
- Adverse events were more common with gabapentin and included dizziness (relative risk [RR] 1.99, 95% CI 1.17 to 3.37), fatigue (RR 1.85, 95% CI 1.12 to 3.05), difficulty thinking (RR 3.34, 95% CI 1.54 to 7.25), and visual disturbances (RR 5.72, 95% CI 1.94 to 16.91). People taking pregabalin were more likely to experience dizziness than those taking other active pain relief (RR 2.70, 95% CI 1.25 to 2.70).
What does current guidance say on this issue?
NICE guidelines on low back pain and sciatica in over-16s state that anticonvulsants should not be offered for managing low back pain. Self-management and exercise programmes are core components of care. Non-steroidal anti-inflammatories (NSAIDs) are the recommended drug treatment, with weak opioids (with or without paracetamol) considered only if NSAIDs are contraindicated, not tolerated or ineffective.
However, for management of sciatica NICE refer to their Neuropathic pain guidelines, which do recommend gabapentin or pregabalin as initial treatment options for neuropathic pain.
NICE Key Therapeutic Topic guidance (2017) notes that “The use of both gabapentin and pregabalin can lead to dependence and these medicines may be misused or diverted.”
What are the implications?
There are few effective drug treatments available for people with non-specific chronic lower back pain. There is no evidence at present to suggest that gabapentinoids are effective. Furthermore, the associated adverse events do not seem to justify prescribing them in this group.
This systematic review, in general, supports current NICE guidance on this topic. The grey area, however, is people with associated sciatica. The studies included in this review were not able to differentiate whether they may benefit.
GPs and Clinical Commissioning Groups may want to consider reviewing local usage of gabapentinoids in people with chronic lower back pain.
Citation and Funding
Shanthanna H, Gilron I, Rajarathinam M, et al. Benefits and safety of gabapentinoids in chronic low back pain: a systematic review and meta-analysis of randomized controlled trials. PLoS Medicine. 2017:14(8):e1002369.
No funding information was provided for this study. Article processing fees were supported by the Canadian Institute of Health Research.
Bibliography
NICE. Low back pain and sciatica in over 16s: assessment and management. NG59. London: National Institute for Health and Care Excellence; 2016.
NICE. Medicines optimisation in long-term pain. KTT21. London: National Institute for Health and Care Excellence; 2017.
NICE. Neuropathic pain in adults: pharmacological management in non-specialist settings. CG173. London: National Institute for Health and Care Excellence; 2013 (updated 2017).
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