The Efficacy and Safety of Botulinum Neurotoxin Type A in Treating Chronic Low Back Pain: A Systematic Review, Meta-Analysis, Trial Sequential Analysis, and Meta-Regression

Background: Chronic low back pain (CLBP) is a leading cause of disability. Botulinum neurotoxin type A (BoNT-A) has strong anti-spasmodic and analgesic effects, suggesting that its local muscular injection can reduce CLBP compared to other therapies. In this systematic review and meta-analysis, we investigated the efficacy and safety of BoNT-A on patients with CLBP. Methods: We searched PubMed, Scopus, Cochrane, and Web of Science databases for studies comparing BoNT-A to other therapies in terms of functional improvement and pain improvement as measured by visual analog scale (VAS) and clinically significant improvement in pain (50% or greater reduction in VAS score). We employed trial sequential analysis (TSA) to confirm the findings. The GRADE approach was employed to assess the overall quality of the evidence. Results: The search yielded nine studies, seven randomised clinical trials (RCTs), and two prospective observational studies. Compared to the control, BoNT-A increased the incidence of clinically significant improvement in pain (RR = 4.82, 95% CI (3.00, 7.76), p < 0.00001) and functional improvement (RR = 3.81, 95% CI (2.40, 6.04), p < 0.00001) (low-certainty evidence), and reduced VAS score (MD = −1.62, 95% CI (−3.13, −0.11), p = 0.04) (very low-certainty evidence). Subgroup analysis showed that BoNT-A is effective against normal saline (moderate-certainty evidence), and it was comparable to steroids and local anaesthetics (very low-certainty evidence). TSA confirmed the findings regarding clinical improvement in pain and functional improvement. Conclusion: BoNT-A is a tolerable and effective treatment for CLBP with a longer duration of action. Future high-quality studies are needed to confirm our findings. Significance: This paper provides good evidence that BoNT-A may be employed in patients suffering from resistant chronic low back pain not responding to normal saline injection due to its higher efficacy and longer duration of action. Compared to steroids and local anaesthetics injections, there is not enough data to draw a firm conclusion and future studies are needed.