Determining Construct Validity of a Patient-Reported Outcome Measure for Birthmarks on the Face and Body.

Background: The FACE-Q Craniofacial module includes a scale that measures how bothered an individual is by the appearance of a birthmark on the face or body. Objective: To determine if the Birthmark scale measuring appearance of the birthmark has evidence of construct validity among children and young adults, aged 8-29 years old, with a birthmark on the face or body. Methods: Participants were recruited as part of the field test of the FACE-Q Craniofacial module. Construct validity of the Birthmark scale was examined using a priori hypotheses testing. Results: Two hundred seventy participants were included, who were predominantly female (60.4%) and had a facial birthmark (71.5%). The Birthmark scale correlated ( p  ≤ 0.01) with scale scores for Face, Appearance Distress, Psychological, School, and Social. Scores for participants with more "noticeable" birthmarks were ( p  ≤ 0.01) associated with worse Birthmark scale scores. Conclusion: The findings support that the Birthmark scale can be used to measure the patient's perspective of the appearance of their birthmark, providing a means for clinicians to incorporate the patient's view in shared decision-making and research.