Epidural steroid injections compared with gabapentin for lumbosacral radicular pain

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Epidural steroid injections compared with gabapentin for lumbosacral radicular pain
Key Take-Away: 
  • Although epidural steroid injection might provide greater benefit than gabapentin for some outcome measures, the differences are modest and are transient for most people.
  • There were no significant differences for the primary outcome measure at one month (mean pain score 3.3 (SD 2.6) and mean change from baseline −2.2 (SD 2.4) in epidural steroid injection group versus 3.7 (SD 2.6) and −1.7 (SD 2.6) in gabapentin group.

Low back pain has been the main cause of years lost to disability, with lifetime prevalence between 50% and 90%. Epidural steroid injections are most commonly used treatment for pain relief being used relatively more with greater effects in radicular pain than mechanical spine pain.

ABSTRACT: 
Background: 

Low back pain has been the main cause of years lost to disability, with lifetime prevalence between 50% and 90%. Epidural steroid injections are most commonly used treatment for pain relief being used relatively more with greater effects in radicular pain than mechanical spine pain. A number of controlled studies have shown that treatment with gabapentinoids can be effective for lumbosacral radicular pain but there is paucity of evidence establishing the relative effects of these two common treatments.

 

  • Rationale behind research
  1. Gabapentin and epidural steroid injections are often used to treat lumbosacral radiculopathy and can provide benefit for a subset of patients
  2. However, there is a paucity of comparative study evidence of these two treatments
  • Objective

To evaluate whether an epidural steroid injection or gabapentin is a better treatment for lumbosacral radiculopathy

Methods: 

 

NOTE: Randomization was adequately done using computer generated codes stratified by sites + Blinding involved patients, research nurse and evaluating physicians

Study outcomes

  • Primary outcome: The score of average leg pain on 0-10 numerical rating scale was recorded at 1 and 3 months which reflects average pain experienced during week before follow-up
  • Secondary outcomes: Worst leg pain over the past week, average and worst back pain, score on Oswestry disability index, adverse effects and complications, reduction in analgesic drugs and a positive outcome defined as a ≥2 point decrease in leg pain coupled with a positive global perceived effect
  • Time-points
    • Efficacy: Baseline, 1 month, 3 months
    • Side effects: Baseline, 1 month, 3 months

 

Results: 

 

Baseline: Two treatment groups were quite similar at baseline except that epidural steroid injection group contained one more women (n=73)

Primary outcome

  • At one month, both groups showed improvement in average leg pain score, mean (SD) = 3.3 (2.6) and mean change from baseline (SD) =  −2.2 (2.4) in epidural steroid injection group versus 3.7 (2.6) and −1.7 (2.6) in gabapentin group, but there was no significant difference between groups (adjusted difference 0.4 points, 95% CI: −0.3 to 1.2; P=0.25)
  • At three months, there was improvement in average leg pain score, mean (SD) = 3.4 (2.7) and mean change from baseline (SD) = −2.0 (2.6) in epidural steroid injection group versus mean 3.7 (2.8) and −1.6 (2.7) in gabapentin group, but there was no significant difference between groups (0.3 points, −0.5 to 1.2; P=0.43)

​Figure 1: Reduction in Average Leg Pain Score

Secondary outcome

  • Worst leg pain
  • At one month: Epidural steroid injection had a greater reduction in worst leg pain (-3.0, SD 2.8) than with gabapentin (-2.0, SD 2.9 P= 0.04) and chances was more of positive successful outcome (66% V 46%number needed to treat= 5.0, 95% confidence interval 2.8 to 27.0 P=0.02)
  • At 3 months of treatment, there were no significant differences between treatments

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Figure 2: Reduction in Worst Leg Pain Score

Proportion of patients reporting one or more adverse events

  • From injection: Epidural steroid injection group, 8% (n=6) & gabapentin group, 10% (n=7)
  • From drug treatment (capsules): Epidural steroid injection group, 42% (n=30) & gabapentin group, 51% (n=37)
Conclusion: 

There were modest improvements in pain and function with both the treatments however some of the outcomes were in favor of epidural steroid injections but those were very small and temporary.

The similarities in outcomes of both treatments suggest that a trial with neuropathic drugs can be a first line treatment option. Results of placebo controlled studies are mixed which indicates small effect size. An open label three arm study has shown that combination treatment with epidural steroid injections plus drugs and physical therapy was able to provide superior benefit to stand alone treatment on some of outcome measures.

 

BMJ 2015; 350
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