A systematic review and meta-analysis of 301 placebo-controlled randomized trials has found that only about 10% of nonsurgical and noninterventional treatments for low back pain provide small but statistically significant analgesic benefits beyond placebo effects. Even for these treatments, the reductions in pain intensity were modest and may not be clinically meaningful.

In their study, published in BMJ Evidence-Based Medicine, Aidan G Cashin, of the Centre for Pain IMPACT at Neuroscience Research Australia and the School of Health Sciences at the University of New South Wales in Sydney, and colleagues analyzed data from 377 treatment comparisons that covered 56 treatments or treatment combinations. Researchers assessed the efficacy of treatments separately for acute (less than 12 weeks) and chronic (greater than or equal to 12 weeks) low back pain, and evaluated both nonpharmacological and pharmacological interventions.

For acute low back pain, only nonsteroidal anti-inflammatory drugs (NSAIDs) demonstrated efficacy with moderate certainty evidence, providing a modest 3.8-point reduction on a 0 to 100 pain scale compared with placebo. The study found with moderate certainty that exercise, glucocorticoid injections, and paracetamol were not efficacious and are unlikely to be suitable treatment options for acute low back pain.

For chronic low back pain, five treatments demonstrated efficacy with moderate certainty evidence:

• exercise (7.9-point reduction)
• spinal manipulative therapy (6.4-point reduction)
• taping (6.3-point reduction)
• antidepressants (4.9-point reduction)
• transient receptor potential vanilloid 1agonists (8.2-point reduction)

Moderate certainty evidence indicated that anesthetics and antibiotics were not efficacious for chronic low back pain.

The remaining treatments had inconclusive evidence due to small sample sizes, imprecision, or low and very low certainty evidence. The study found that 62% of trials were at high risk of bias, which affected confidence in many of the reported outcomes. Certainty of evidence was moderate for 16% of treatment comparisons, low for 36%, and very low for 48%. No comparisons achieved high certainty.

"This is the most comprehensive systematic review of placebo-controlled randomized trials investigating nonsurgical and noninterventional treatments for nonspecific low back pain, including 301 trials on 56 different treatments or treatment combinations," the researchers wrote.

The review used established methodological tools, employing the PEDro scale to assess the risk of bias and the GRADE approach to evaluate the certainty of evidence. The findings suggest that while some treatments provide small benefits beyond placebo, their clinical significance remains uncertain. According to the American College of Physicians and the American Pain Society, pain reductions in the 5 to 10 point range on a 0 to 100 scale are considered small and may have limited clinical relevance.

The researchers acknowledged several limitations, including challenges in designing appropriate placebo controls, particularly for nonpharmacological interventions such as exercise and psychological therapies. They also noted heterogeneity in the quality of placebo controls across studies, which may influence the reliability of comparisons.

They called for additional high-quality, placebo-controlled trials to reduce uncertainty in efficacy estimates for many treatments, along with improved placebo control designs for complex interventions.

"Further high-quality, placebo-controlled trials are warranted to address the remaining uncertainty in treatment efficacy along with greater consideration for the design of placebos of nonsurgical and noninterventional treatments," they concluded.

The investigators declared no competing interests.