Botulinum toxin-A a potential treatment for painful joint disease
Intra-articular injections of botulinum toxin-A (BT) deliver substantial short-term benefits in terms of pain reduction in patients with refractory joint pain, according to a meta-analysis.
Researchers searched multiple electronic databases, as well as grey literature, for studies evaluating the effect of BT intra-articular injections in the treatment of painful osteoarticular disease.
A total of six studies involving 382 patients were included in the meta-analysis, which was performed by comparing the numeric rating scale (NRS; from 0 to 10) at baseline and at 1 or 2 months and 6 months after treatment between the BT and control groups. A separate comparison was made between low- and high-dose BT at a follow-up of 1 or 2 months.
Of the five trials comparing NRS at 1 or 2 months regardless of the dose of BT, four reported that BT had a positive effect on the NRS compared with the control treatment, whereas the remaining study found no effect. The overall weighted mean difference was -1.10 (95 percent CI, -1.62 to -0.58; p<0.0001; I2=63 percent).
Of the four trials evaluating the effect of low-dose BT (100 units) on the NRS at 1 or 2 months, three showed positive results when compared with the control treatment; the fourth study failed to find any effect. The overall weighted mean difference was -0.95 (-0.02 to -1.88; p=0.05; I2=67 percent).
Data from the two trials evaluating the effect of high-dose BT (200 units) indicated that the agent had an almost zero effect on the NRS at 1 or 2 months, with an overall weighted mean difference of 0.13 (-0.55 to 0.81; p=0.71; I2=0 percent).
Data from the three trials evaluating NRS at 6 months reported an overall weighted mean difference of -0.57 (-1.98 to 0.83; p=0.42; I2=73 percent).
Researchers attributed the efficacy of BT-A in reducing pain in painful joint diseases to the ability of BT-A to block the release of neuropeptides, such as substance P and calcitonin gene-related peptide, which are key mediators of neurogenic inflammation and pain. This particular effect of the agent has been demonstrated in previous studies. [Pain 2013;154:2547–53; Chin J Plast Surg 2009;25:50–3; BJU Int 2008;101:366–70; J Urol 2006;175:1138–42]