Development and validation of a Scale for Acne Scar Severity (SCAR-S) of the face and trunk.

Background: scarring is an important component of overall acne severity, but there are no global scales for its evaluation inclusive of the face and trunk.
Objective: our objective was to develop a global scale for acne scar severity inclusive of the trunk and the face.
Methods: a six-category global severity scale (SCAR-S) was developed for assessment of acne scarring at each of the face, chest, and back. We evaluated SCAR-S against acne severity and patient-reported scar severity.
Results: of 973 subjects, 73% reported acne scarring. Self-assessment of scarring was associated with facial SCAR-S and overall SCAR-S scores (p < .001, r = .31 and .30, respectively). Acne scarring was observed at the face in 87%, the back in 51%, and the chest in 38%. Clinically relevant scarring (mild or greater) at each of these regions was 55%, 24%, and 14%, respectively. Acne severity correlated with SCAR-S (p < .001) for the back (r = .612), the chest (r = .548), and the face (r = .514). Acne duration correlated with patient-reported severity of scarring (r = .244) and overall SCAR-S scores (r = .152). Clinically relevant scarring increased with acne duration.
Conclusion: SCAR-S is a practical, validated, global system for acne scar evaluation and is clinically relevant in overall severity grading of acne.