5. Needle-free electronically-controlled jet injector treatment with bleomycin is efficacious and well-tolerated in patients with severe keloids: results of a randomized, double-blind, placebo-controlled trial. 129 5. moderate adverse events including ulcerations, necrosis, infection, pain, and hyperpigmentation. Yet, another randomized controlled trial in keloids also found good efficacy without adverse events with a lower dosage of 0.1 U bleomycin per cm2.24 This study also showed that with this dosage, no systemic uptake of bleomycin takes place. Therefore, in our study we chose to use the lower bleomycin dose of 0.1 U/cm2 which we considered to be safer for repetitive administrations. As a result, bleomycin treatment was generally well-tolerated, with only two patients developing transient superficial necrosis of the treated keloid, which did not lead to treatment discontinuation. However, we recommend to use a concentration of 0.2U/cm², when administering bleomycin via EPI for the treatment of severe keloids due to the spilled volume of 50%. In the study by Erlendson et al., a single treatment with 5-FU and TCA was administered using an EPI in patients with hypertrophic scars.30 Remarkably, in their study a lower median procedure-related NRS pain score of 2.0 vs. 5.6 in our trial was observed. However, in general, hypertrophic scars are less painful than severe keloids. In a previous study by our group with intralesional EPI-assisted TCA treatment in keloids, we found a lower mean NRS pain score of 3.8.23 The higher pain scores in the present study could be related to the burning pain sensation that bleomycin can cause.31 However, also EPIassisted injections with placebo resulted in a higher NRS pain score of 5.4. Therefore, the higher injection-related pain scores in our current study is more likely related to our specific patient population that suffered from extremely severe keloids, of which some were already very painful upon palpation. One of the strengths of this study is the design of the trial. In addition, we incorporated both objective outcomes such as volume reduction measured with a 3D-camera using a standard operating procedure,26 and subjective outcomes such as POSAS, NRS pain and patient satisfaction. Moreover, to minimize recall bias of adverse events, patients were instructed to take pictures of the treated area and report potential adverse events via an e-diary mobile application on a daily basis.
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