Immediate Injection of Botulinum Toxin Type A After Keloid Scar Revision to Prevent Keloid Recurrence: a Prospective, Split-scar, Double-blind, Randomized Controlled Study

  • End date
    Dec 25, 2023
  • participants needed
  • sponsor
    National Cheng-Kung University Hospital
Updated on 25 October 2022
Accepts healthy volunteers


The prospective, split-scar, double-blind, randomized controlled study will enroll the patients who are older than 20 years with progressive keloid lesion which is symmetric. Botulinum toxin A will be injected into half of each keloid revision wound immediately after skin closure. The scars will be assessed at 1-year follow-up with Vancouver Scar Scale (VSS), Patient and Observer Scar Assessment Scale (POSAS), and the Cutometer.


Continuous variables will be reported as the mean ± standard deviation(SD). Each aspect of the VSS score, POSAS score, and the Cutometer parameters of each scar half between the BTA and control groups will be analyzed longitudinally using the paired t test. The interrater consistency will be evaluated using the Spearman rho. All analyses will be performed with IBM SPSS Version 23.0 (IBM Corp., Redmond, Wash.). A value of p < 0.05 is considered to indicate statistical significance.

The sample size was calculated based on the results of the investigators' aforementioned study published in 2019. Thirty patients underwent keloid revision and then received radiation therapy based on our treatment protocol. The postoperative Vancouver Scar Scale score was 4.15 ± 1.74. If treatment could improve VSS score by 1, which was considered clinically significant, approximately 26 patients would have been necessary to provide a result with a real significance (using the same SD and considering the standard α error of 0.05 and a power of 0.8). Assuming a 20% non-compliance rate for follow-up evaluation, the sample size was increased to 32 patients.

Condition Scar Keloid
Treatment 0.9% Sodium Chloride Injection, Botulinum Toxin Type A Injection [Botox]
Clinical Study IdentifierNCT05072821
SponsorNational Cheng-Kung University Hospital
Last Modified on25 October 2022


Yes No Not Sure

Inclusion Criteria

Adult (20 years or older)
Progressive keloid lesion that is bilaterally symmetric, mandibular area, anterior chest or suprapubic area, for example
At least 4 cm in length
Repeated or uncontrolled recurrence, and unendurable symptoms with poor response to conservative modalities
Valid written informed consent provided for surgery and trial inclusion

Exclusion Criteria

Allergy to botulinum toxin
Previous botulinum toxin injection at the lesion within 6 months before enrollment
Myasthenia gravis
Focal infection signs
Pregnant or breastfeeding woman
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