Little evidence that gabapentinoids work for low back pain

Gabapentin showed minimal improvement of pain compared with placebo, while pregabalin was not as effective compared to other types of analgesic medication, the study showed.

Evidence on the use of gabapentinoids in chronic low back pain (CLBP) is limited and there is significant risk of adverse effects without any demonstrated benefit, so their use and costs merit caution, a study concluded.

A systematic review and meta-analysis of eight randomized control trials analyzed the use of gabapentinoids for the treatment of chronic low back pain of more than three months in adult patients. Results were published Aug. 15 at PLOS Medicine.

Gabapentin (three studies, n=185) showed minimal improvement of pain compared with placebo (mean difference [MD], 0.22 units; 95% CI, −0.5 to 0.07; I2=0%; GRADE: very low). Three studies compared pregabalin with other types of analgesic medication (n=332) and showed greater improvement in the other analgesic group (MD, 0.42 units; 95% CI, 0.20 to 0.64; I2=0; GRADE: very low).

Studies using pregabalin as an adjuvant (n=423) were not pooled due to heterogeneity, but the largest of them showed no benefit of adding pregabalin to tapentadol, researchers noted. There were no deaths or hospitalizations reported. Compared with placebo, the following adverse events were more commonly reported with gabapentin:

  • dizziness (risk ratio [RR], 1.99; 95% CI, 1.17 to 3.37; I2=49),
  • fatigue (RR, 1.85; 95% CI, 1.12 to 3.05; I2=0),
  • difficulties with mentation (RR, 3.34; 95% CI, 1.54 to 7.25; I2=0), and
  • visual disturbances (RR, 5.72; 95% CI, 1.94 to 16.91; I2=0).

The numbers needed to harm were seven for dizziness (95% CI, 4 to 30), eight for fatigue (95% CI,4 to 44), six for difficulties with mentation (95% CI, 4 to 15) , and six for visual disturbances (95% CI, 4 to 13) . The GRADE evidence quality was very low for dizziness and fatigue, low for difficulties with mentation, and moderate for visual disturbances. Functional and emotional improvements were reported by few studies and showed no significant improvements.

The limited and low-quality evidence suggests increased risk of adverse effects with only minimal benefit for gabapentin compared with placebo and no evidence for benefit with pregabalin compared with other analgesics, yet the drugs are widely prescribed, the authors noted.

“In England, there was a 46% and 53% rise in the prescription use of [gabapentin] and [pregabalin] respectively from 2011 to 2013 alone. A recent Canadian study showed that the off-label use of [pregabalin] is as high as 75%, and the most prevalent condition of use was [chronic low back pain],” they wrote.