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Gabapentinoids ineffective for back pain

Evidence on the use of the gabapentinoids pregabalin and gabapentin to treat chronic low back pain was limited, but indicated significant risk for adverse events with no pain relief, according to a recent meta-analysis published in PLoS Medicine.

“Both [pregabalin and gabapentin] ... are considered to be very effective for neuropathic pain conditions,” Harsha Shanthanna, MBBS, MD, DNB, FIPP, department of anesthesiology at McMaster University, Hamilton, Ontario, Canada, and colleagues wrote. “Attempts at exploiting their therapeutic potential for other pain conditions have shown mixed results. Use of gabapentinoids for [chronic lower back pain] requires slow titration to therapeutic doses and establishing maintenance on a long-term basis. With prolonged treatment, the potential gain over possible adverse effects and risks could become unclear.”

Researchers searched Cochrane, MEDLINE and EMBASE databases for randomized control trials reporting the use of gabapentinoids for chronic lower back pain treatment of 3 months or more in adult patients. These studies used mean differences or RR with their corresponding 95% CIs as their outcomes and I² in percentage representing the percentage variability in effect estimates that could be explained by heterogeneity. GRADE (Grading of Recommendations Assessment, Development, and Evaluation) was used to assess the quality of evidence.

Shanthanna and colleagues found that three of the studies compared pregabalin to other types of analgesic medication and showed greater improvement in the other analgesic group (MD = 0.42 units; 95% CI 0.2-0.64; I² = 0; GRADE: very low).. Three other studies compared gabapentin with placebo, and found that the improvement of pain was minimal (mean difference = 0.22 units; 95% CI –0.5 to 0.07; I² = 0%; GRADE: very low) among its 185 participants. Two studies that used pregabalin as an adjuvant therapy were not pooled due to heterogeneity, but the largest of them showed no benefit of adding pregabalin to tapentadol among its 432 participants.

Researchers also noted that the GRADE evidence quality was moderate for visual disturbances, low for difficulties with mentation, and very low for dizziness and fatigue. Functional and emotional improvements were reported by few studies and showed no significant improvements. No deaths or hospitalizations were recorded.

In addition, and when compared with placebo, the following adverse events were more commonly reported with the use of gabapentin: fatigue (RR = 1.85; 95% CI, 1.12-3.05; I² = 0); dizziness (RR = 1.99; 95% CI, 1.17-3.37; I² = 49); difficulties with mentation (RR = 3.34; 95% CI, 1.54-7.25; I² = 0); and visual disturbances (RR = 5.72; 95% CI, 1.94-16.91; I² = 0).

“The existing evidence does not support the use of gabapentinoids for predominant [chronic lower back pain], and calls for larger, high quality [randomized controlled trials] to more definitively inform this issue,” Shantanna and colleagues wrote.

The researchers’ findings are the latest to suggest pharmacological approaches may not work for back pain. A recent study found that NSAIDS offered limited benefit, while a second study concluded that massage therapy improved the well-being of patients in many of the outcomes studied.

In addition, the ACP recently suggested that clinicians advise their patients with acute or subacute low back pain to select a nonpharmacologic treatment approach such as tai chi or yoga, a decision it based on a systematic review of randomized controlled trials published through April 2015. – by Janel Miller

Disclosure: The researchers report no relevant financial disclosures.