Gabapentin Appears to Lack Analgesic Efficacy for Chronic Low Back Pain

BALTIMORE, Md.—Does gabapentin reduce pain and improve function and quality of life in patients with chronic low back pain? Results of a randomized, placebo-controlled trial suggest the answer is “no,” despite the frequent prescribing of the anticonvulsant for this condition.

To determine whether gabapentin reduced pain and improved function and quality of life in chronic low back pain, Joseph Atkinson, MD, of the VA San Diego Healthcare System, San Diego, Calif., and colleagues randomized patients to either gabapentin (up to 3600 mg/day, or maximum tolerable dose) or placebo. To be included in the study, patients had to have chronic back pain (T-6 vertebra and below) daily for more than 6 months due to degenerative disk disease, without sciatica, and have no significant current psychiatric illness or substance use disorder.

Of the 113 patients randomized, 73 (66%) completed the 12-week study; 78% were male, 47% were married, 70% were white, and mean age was 54.6 years (range, 43-66.2 years). All had longstanding pain (16.9 ± 13.4 years) of moderate intensity on the Descriptor Differential Scale (DDS, 9.1 ± 4.3), 72% of whom had been treated primarily with nonsteroidal analgesics; 95% had not undergone back surgery. Using the Quebec Regional Classification, 54% had back pain only; 27%, back pain plus radiation above the knee; and 23%, back pain plus radiation below the knee.

Gabapentin analgesia was evaluated comparing differences versus placebo using change scores calculated from baseline to last observation on DDS pain intensity. Pain decreased significantly over time (P<0.0001); those receiving placebo reported pain reductions of approximately 30% from baseline. No analgesic effect was observed for gabapentin vs placebo (P=0.4237); results were similar for function and quality of life. When back pain only was compared to pain with radiation to the lower extremity, no differential effects were found.

Investigators reported these results at The American Pain Society’s 29th Annual Scientific Meeting.