Supplementary Material for: Patient-reported outcomes of medical tattooing for capillary malformations

Background Patients with capillary malformations (CMs) may undergo medical tattooing (MT) as an alternative to laser therapy. But, little is known about treatment results and impact from the patients’ perspective. Objectives In this cross-sectional digital survey study, we evaluated the patient-reported outcomes of MT for CMs. Methods MT practices were identified via the Dutch Association of Skin Therapists and Google. These practices invited all their CM-patients who had undergone MT between January 2011–September 2021 to participate. Baseline and treatment characteristics, tattooing effectiveness, patient satisfaction with treatment outcomes, and complications were evaluated using a custom-made online survey. Quality of life (QoL) was assessed with the Dermatology Life Quality Index (DLQI) questionnaire. Factors associated with treatment effectiveness and patient satisfaction were identified via bivariate analysis and ordinal logistic regression analysis. Results Most of the 89 respondents were female (69%). Almost all CMs were located on the face (90%) and mainly (dark)red (74%). Nearly all patients had undergone laser therapy (91%). Median number of tattooing sessions was 5 (IQR: 4.0-8.0). Thirty-seven percent of the patients perceived >75% color reduction. Younger patients were more likely to obtain lower treatment effectiveness (OR 0.44, 95%CI: 0.20–0.97). Most patients (83%) were satisfied with treatment results. Patients with lighter- (OR 0.30, 95%CI: 0.13–0.72), non-facial- (OR 0.15, 95%CI: 0.03–0.89) and hypertrophic CMs (OR 0.30, 95%CI: 0.11–0.82) were less likely to be satisfied with treatment outcomes. Patients with lighter skin types were more satisfied (OR 2.89, 95%CI: 1.23–6.80). Complications included transient pain (23%), bleeding (3.4%), hypertrophic scarring (1.1%), hypopigmentation (1.1%), and a halo around the tattoo (1.1%). Conclusion MT seems a valid alternative treatment in addition to laser therapy for CMs, with mild complications. Most patients are (very)satisfied with treatment results, while color reduction is incomplete. Hence, it seems appropriate to decide together with patients whether or not to use MT as primary treatment or secondary to laser therapy