Psychometric Findings for the SCAR-Q Patient-Reported Outcome Measure Based on 731 Children and Adults with Surgical, Traumatic, and Burn Scars from Four Countries

Background: Each year, millions of individuals develop scars secondary to surgery, trauma, and/or burns. Scar-specific patient-reported outcome measures to evaluate outcomes are needed. To address the gap in available measures, the SCAR-Q was developed following international guidelines for patient-reported outcome measure development. This study field tested the SCAR-Q and examined its psychometric properties. Methods: Patients aged 8 years and older with a surgical, traumatic, and/or burn scar anywhere on their face or body were recruited between March of 2017 and April of 2018 at seven hospitals in four countries. Participants answered demographic and scar questions, the Fitzpatrick Skin Typing Questionnaire, the Patient and Observer Scar Assessment Scale (POSAS), and the SCAR-Q. Rasch measurement theory was used for the psychometric analysis. Cronbach's alpha, test-retest reliability, and concurrent validity were also examined. Results: Consent was obtained from 773 patients, and 731 completed the study. Participants were aged 8 to 88 years, and 354 had surgical, 184 had burn, and 199 had traumatic scars. Analysis led to refinement of the SCAR-Q Appearance, Symptoms, and Psychosocial Impact scales. Reliability was high, with person separation index values of 0.91, 0.81, and 0.79; Cronbach alpha values of 0.96, 0.91, and 0.95; and intraclass correlation coefficient values of 0.92, 0.94, and 0.88, respectively. As predicted, correlations between POSAS scores and the Appearance and Symptom scales were higher than those between POSAS and Psychosocial Impact scale scores. Conclusions: With increasing scar revisions, a scar-specific patient-reported outcome measure is needed to measure outcomes that matter to patients from their perspective. The SCAR-Q represents a rigorously developed, internationally applicable patient-reported outcome measure that can be used to evaluate scars in research, clinical care, and quality improvement initiatives.