Efficacy and safety of botulinum toxin type A for upper limb spasticity after stroke or traumatic brain injury: a systematic review with meta-analysis and trial sequential analysis

INTRODUCTION: Muscle spasticity is a positive symptom after stroke and traumatic brain injury. Botulinum toxin type A (BoNT-A) injection is widely used for treating post stroke and traumatic brain injury spasticity. This study aimed to evaluate efficacy and safety of BoNT-A for upper limb spasticity after stroke and traumatic brain injury and investigate reliability and conclusiveness of available evidence for BoNT-A intervention. EVIDENCE ACQUISITION: We searched electronic databases from inception to September 10 of 2016. Randomized controlled trials comparing the effectiveness between BoNT-A and placebo in stroke or traumatic brain injury adults with upper limb spasticity were included. Reliability and conclusiveness of the available evidence were examined with trial sequential analysis. EVIDENCE SYNTHESIS: From 489 citations identified, 22 studies were included, reporting results for 1804 participants. A statistically significant decrease of muscle tone was observed at each time point after BoNT-A injection compared to placebo (SMD at week 4=-0.98, 95% CI: -1.28 to -0.68; I-2=66%, P=0.004; SMD at week 6=-0.85, 95% CI: -1.11 to -0.59, I-2=1.2%, P=0.409; SMD at week 8=-0.87, 95% CI: -1.15 to -0.6, I-2=0%, P=0.713; SMD at week 12=-0.67, 95% CI: -0.88 to -0.46, I-2=0%, P=0.896; and SMD over week 12=-0.73, 95% CI: -1.21 to -0.24, I-2=63.5%, P=0.065). Trial sequential analysis showed that as of year 2004 sufficient evidence had been accrued to show significant benefit of BoNT-A four weeks after injection over placebo control. BoNT-A treatment also significantly reduced Disability Assessment Scale Score than placebo at 4, 6 and 12-week follow-up period (WMD=-0.33, 95% CI: -0.63 to -0.03, I-2=60%, P=0.114; WMD=-0.54, 95% CI: -0.74 to -0.33, I-2=0%, P=0.596 and WMD=-0.3, 95% CI: -0.45 to -0.14, I-2=0%, P=0.426 respectively), and significantly increased patients' global assessment score at week 4 and 6 after injection (SMD=0.56, 95% CI: 0.28 to 0.83; I-2=0%, P=0.681 and SMD=1.11, 95% CI: 0.4 to 1.77; I-2=72.8%, P=0.025 respectively). No statistical difference was observed in the frequency of adverse events between BoNT-A and placebo group (RR=1.36, 95% CI [0.82, 2.27]; I-2=0%, P=0.619). CONCLUSIONS: As compared with placebo, BoNT-A injections have beneficial effects with improved muscle tone and well-tolerated treatment for patients with upper limb spasticity post stroke or traumatic brain injury.