Commonly prescribed painkiller may not be effective in controlling lower back pain

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A study published in the journal Neurology shows that pregabalin is not effective in controlling the pain associated with lumbar spinal stenosis, a common cause of chronic lower back pain in older adults.

“Chronic low back pain is one of the most common reasons why older adults go to the doctor and lumbar stenosis is the leading indication for surgery in this age group,” says John Markman, director of the Translational Pain Research Program in the University of Rochester Department of Neurosurgery and lead author of the study. “While physicians have increasingly looked for medication alternatives to opioid pain medication like gabapentin and pregabalin to help these patients manage their pain, until now there has been no credible evidence as to whether or not these treatments are effective for this problem.”

Pregabalin, which is marketed by Pfizer under the name Lyrica, is approved to treat chronic pain associated with shingles, spinal cord injury, fibromyalgia, and diabetic peripheral neuropathy. However, it is also commonly prescribed as an “off label” treatment for chronic low back pain syndromes like lumbar spinal stenosis.

The randomised, double-blind, active placebo-controlled, two-period, crossover study involved 29 patients randomised to receive pregabalin followed by active placebo, or active placebo followed by pregabalin. Each treatment period lasted 10 days, including a two-step titration. Periods were separated by a 10-day washout period, including a three-day taper phase after the first period. The primary outcome variable was the time to first moderate pain symptom (Numeric rating scale score ≥4) during a 15-minute treadmill test (Tfirst). Secondary outcome measures included pain intensity at rest, pain intensity at the end of the treadmill test, distance walked, and validated self-report measures of pain and functional limitation including the Roland-Morris Disability Questionnaire, modified Brief Pain Inventory–Short Form, Oswestry Disability Index, and Swiss Spinal Stenosis Questionnaire.

The authors write: “No significant difference was found between pregabalin and active placebo in the distribution of time to first moderate pain (difference in median Tfirst = 1.08 [95% confidence interval – 2.25 to 0.08], p=0.61). No significant differences were detected between pregabalin and active placebo regarding any of the other treadmill test outcomes or patient-reported outcome measures of pain or functional disability, with the exception of the Roland-Morris Disability Questionnaire, which favoured placebo.”

In terms of safety, 19 of the 28 subjects (64.3%) treated with pregabalin experienced adverse events, as did nine of the 26 subjects (34.6%) treated with active placebo. Dizziness was the most common adverse event during pregabalin treatment, experienced by 12 of the 28 (42.9%) patients. No deaths or serious adverse events were reported. Two subjects discontinued participation because of adverse events while treated with pregabalin; one experienced dizziness and the other dizziness, confusion, and vision changes. No subjects discontinued participation due to adverse events during the active placebo period.

“Given the cost and potential side effects associated with pregabalin, it is critical that we understand the efficacy of this drug,” Markman says. “This study convincingly demonstrates a lack of relief with pregabalin for the walking pain associated with lumbar spinal stenosis.” 

Given the rating of the results as class I evidence, this study provides critical proof of concept for a clinical trial method to study treatments for neurogenic claudication and spinal stenosis going forward.

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