Shape-based evaluation of acne scars is subjective and does not produce strong agreement, according to a non-interventional study involving dermatologist assessments.

Researchers used the Jacob clinical classification system to define 3 primary shapes of scars. Independent technicians looked at the investigators' markings on digital images to determine agreement. Raters assessed scars on the same patients in the morning and afternoon. Among the results:

• ~50% of scars were identified by all raters.

• ~75% of scars were identified by at least 2 of 3 raters, considered weak agreement.

• Shape classifications of icepick, boxcar, and rolling scars differed significantly between raters, as well as for the same raters at consecutive sessions.

• Only two-thirds of scars were identified identically in consecutive sessions by the same rater.

• There was poor agreement among investigators for very small scars.

• Repeatability of identification of scars ≥2.0 mm was acceptable.

Citation: Kang S, Lozada V, Bettoli V, et al. New atrophic acne scar classification: Reliability of assessments based on size, shape, and number. J Drugs Dermatol. 2016;15(6):693-702.