Treatment Outcome Measurement Instruments for Port Wine Stains: A Systematic Review of Their Measurement Properties

Background: A plethora of outcome measurement instruments (OMIs) are being used in port wine stain (PWS) studies. It is currently unclear how valid, responsive, and reliable these are. Objectives: The aim of this systematic review was to appraise the content validity and other measurement properties of OMIs for PWS treatment to identify the most appropriate instruments and future research priorities. Methods: This study was performed using the updated Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) methodology and adhered to PRISMA guidelines. Comprehensive searches in Medline and Embase were performed. Studies in which an OMI for PWS patients was developed or its measurement properties were evaluated were included. Two investigators independently extracted data and assessed the quality of included studies and instruments to perform qualitative synthesis of the evidence. Results: In total, 1,034 articles were screened, and 77 full-text articles were reviewed. A total of 8 studies were included that reported on 6 physician-reported OMIs of clinical improvement and 6 parent- or patient-reported OMIs of life impact, of which 3 for health-related quality of life and 1 for perceived stigmatization. Overall, the quality of OMI development was inadequate (63%) or doubtful (37%). Each instrument has undergone a very limited evaluation in PWS patients. No content validity studies were performed. The quality of evidence for content validity was very low (78%), low (15%), or moderate (7%), with sufficient comprehensibility, mostly sufficient comprehensiveness, and mixed relevance. No studies on responsiveness, minimal important change, and cross-cultural validity were retrieved. There was moderate- to very low-quality evidence for sufficient inter-rater reliability for some clinical PWS OMIs. Internal consistency and measurement error were indeterminate in all studies. Conclusions: There was insufficient evidence to properly guide outcome selection. Additional assessment of the measurement properties of OMIs is needed, preferentially guided by a core domain set tailored to PWS.