A randomized controlled trial of gabapentin for chronic low back pain with and without a radiating component

Abstract

Gabapentin is prescribed for analgesia in chronic low back pain, yet there are no controlled trials supporting this practice. This randomized, two-arm, 12-week, parallel group study compared gabapentin (forced titration up to 3600 mg daily) to inert placebo. The primary efficacy measure was change in pain intensity from baseline to the last week on treatment measured by the Descriptor Differential Scale; the secondary outcome was disability (Oswestry Disability Index). The intention-to-treat analysis comprised 108 randomized chronic back pain patients (daily pain for ≥ 6 months) whose pain did (43%) or did not radiate into the lower extremity. Random effects regression models which did not impute missing scores were used to analyze outcome data. Pain intensity decreased significantly over time (p < .0001) with subjects on gabapentin or placebo reporting reductions of about 30% from baseline, but did not differ significantly between groups (p = .423). The same results pertained for disability scores. In responder analyses of those who completed 12 weeks (N=72), the proportion reporting at least 30% or 50% reduction in pain intensity, or at least “Minimal Improvement” on the Physician Clinical Global Impression of Change did not differ significantly between groups. There were no significant differences in analgesia between participants with radiating (n = 46) and non-radiating (n = 62) pain either within or between treatment arms. There was no significant correlation between gabapentin plasma concentration and pain intensity. Gabapentin appears to be ineffective for analgesia in chronic low back pain with or without a radiating component.

Anticonvulsants in the treatment of low back pain and lumbar radicular pain: a systematic review and meta-analysis

“…Nine eligible studies were included, with a total of 859 participants (Table 1). 26 ). Only 1 trial included participants with acute symptoms (< 3 mo).…”

“…28,29,34 The mean treatment duration was 6.7 weeks (range 10 d to 12 wk). The anticonvulsants investigated were gabapentinoids (pregabalin 27,29,30 or gabapentin 26,31,32,34 ) and topiramate. 28,33 Most studies applied selfreported numerical pain-rating scales (NPRSs), 26,[28][29][30][31][32]34 and 1 used a descriptorbased pain rating index.…”

“…The anticonvulsants investigated were gabapentinoids (pregabalin 27,29,30 or gabapentin 26,31,32,34 ) and topiramate. 28,33 Most studies applied selfreported numerical pain-rating scales (NPRSs), 26,[28][29][30][31][32]34 and 1 used a descriptorbased pain rating index. 33 Disability was reported using either the Oswestry Disability Index 26,28,29,33 or Roland-Morris Disability Questionnaire.…”

“…28,33 Most studies applied selfreported numerical pain-rating scales (NPRSs), 26,[28][29][30][31][32]34 and 1 used a descriptorbased pain rating index. 33 Disability was reported using either the Oswestry Disability Index 26,28,29,33 or Roland-Morris Disability Questionnaire. 30 Most studies reported immediate or short-term data only.…”

“…26,31,32 There was no effect for pain in the short term (pooled MD -0.0, 95% CI -0.8 to 0.7 on a 0-to 10-point NPRS, 3 studies, Figure 2). The quality of evidence was high (Appendix 5, available at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.171333/-/DC1) but 2 studies 31,32 investigated gabapentin below the recommended dose of 1800-3600 mg/d.…”