The Enigma of Analgesics in Low Back Pain Management: Safety and Efficacy Questions
Despite decades of research, the effectiveness and safety of analgesic medications for treating acute low back pain remain uncertain, according to recent research findings. Michael A. Wewege, a PhD candidate and research fellow at the University of New South Wales and Neuroscience Research Australia in Sydney, emphasizes the need for higher-quality randomized controlled trials that directly compare different analgesics. Until such studies are conducted, he advises caution when prescribing these medications for adults with nonspecific acute low back pain, urging doctors to consider both the latest evidence and their clinical expertise.
Published online on March 22 in the British Medical Journal (BMJ), this study sought to address the limited evidence regarding the comparative efficacy of analgesics such as ibuprofen, acetaminophen, and codeine in the treatment of nonspecific low-back pain, defined as pain lasting less than six weeks.
The researchers conducted a systematic review and analysis of controlled trials that compared analgesics with other analgesics, placebo, or no treatment in patients with acute, nonspecific low back pain. The review encompassed 98 randomized controlled trials, involving 15,134 adults aged 30-60 years, with pain durations ranging from 24 hours to 21 days. The median baseline pain intensity was 65 on a pain scale of 0 to 100.
The trials had varying characteristics: 39% were placebo-controlled, 67% masked both participants and clinicians, and 41% reported industry sponsorship. The studies compared a wide range of analgesic medications, including nonsteroidal anti-inflammatory drugs, paracetamol, opioids, anticonvulsants, antidepressants, muscle relaxants, and corticosteroids, administered singly or in combination, and at varying doses.
The researchers used a network meta-analysis, which integrates direct and indirect information from a network of randomized clinical trials to estimate the comparative effectiveness of multiple treatments. The primary outcomes assessed were reductions in low back pain intensity, measured using visual analogue scales, numerical rating scales, or other ordinal scales, as well as safety, indicated by the number of participants experiencing adverse events.
The results revealed that several medications were associated with significant reductions in pain intensity compared to placebo. However, these findings were characterized by low or very low confidence levels. Medications such as tolperisone, aceclofenac plus tizanidine, pregabalin, and 14 others demonstrated low confidence in reducing pain intensity. Additionally, some medications were associated with increased adverse events, including tramadol, paracetamol plus sustained-release tramadol, baclofen, and paracetamol plus tramadol.
The researchers also found low or very low confidence levels for no difference in the effects of several medications. The review suggested that 14 additional comparisons favored treatment over placebo, with most of these having very low confidence, except for one with low confidence.
These findings were somewhat unexpected, according to Wewege. The study aimed to provide more comprehensive evidence, but the limited number of trials and low confidence in the results came as a surprise. Factors contributing to this low confidence included a high risk of bias in approximately 90% of the trials and significant heterogeneity in effect estimates.
Wewege suggests that clinicians consider medication availability, their own expertise, and patient preferences when selecting an analgesic. Importantly, most patients with acute low back pain tend to recover within a few weeks without any intervention.
Commenting on the study, Dr. Chris Gilligan, associate chief medical officer at Brigham and Women’s Hospital and associate professor of anesthesia at Harvard Medical School, noted that determining the optimal medications for acute low back pain is essential because it is a common condition frequently treated with analgesics. While the study provides some direction regarding medications with stronger evidence for pain reduction, Gilligan emphasized the need to exercise caution given the low or very low confidence in the findings. He also pointed out that data on adverse effects, where the confidence level is mostly moderate to low, might have a more significant impact on prescribing decisions.
Overall, clinicians are advised to be cautious when prescribing analgesics for low back pain. Gilligan emphasized that acute low back pain typically follows a favorable natural course, and clinical practice guidelines often recommend nonpharmacologic therapies as the first-line and second-line treatments. However, it’s important to note that evidence for non-drug therapies also has low or very low confidence levels.
