The Scarbase Duo®: Intra-rater and inter-rater reliability and validity of a compact dual scar assessment tool

• The Scarbase Duo® measures two scar properties: trans-epidermal water loss and colorimetry.
• Intra- and inter-rater reliability was good-to-excellent for TEWL and colorimetry on scars.
• The Scarbase Duo® was validated against other established tools of TEWL and colorimetry assessment.
• The Scarbase Duo® was easy to use and compact, but required link-up to a laptop computer.
• The Scarbase Duo® is a reliable scar assessment tool however clinical use requires standardised conditions.

Objective scar assessment tools were designed to help identify problematic scars and direct clinical management. Their use has been restricted by their measurement of a single scar property and the bulky size of equipment. The Scarbase Duo® was designed to assess both trans-epidermal water loss (TEWL) and colour of a burn scar whilst being compact and easy to use.Twenty patients with a burn scar were recruited and measurements taken using the Scarbase Duo® by two observers. The Scarbase Duo® measures TEWL via an open-chamber system and undertakes colorimetry via narrow-band spectrophotometry, producing values for relative erythema and melanin pigmentation. Validity was assessed by comparing the Scarbase Duo® against the Dermalab® and the Minolta Chromameter® respectively for TEWL and colorimetry measurements.The intra-class correlation coefficient (ICC) was used to assess reliability with standard error of measurement (SEM) used to assess reproducibility of measurements. The Pearson correlation coefficient (r) was used to assess the convergent validity.The Scarbase Duo® TEWL mode had excellent reliability when used on scars for both intra- (ICC = 0.95) and inter-rater (ICC = 0.96) measurements with moderate SEM values. The erythema component of the colorimetry mode showed good reliability for use on scars for both intra-(ICC = 0.81) and inter-rater (ICC = 0.83) measurements with low SEM values. Pigmentation values showed excellent reliability on scar tissue for both intra- (ICC = 0.97) and inter-rater (ICC = 0.97) with moderate SEM values.The Scarbase Duo® TEWL function had excellent correlation with the Dermalab® (r = 0.93) whilst the colorimetry erythema value had moderate correlation with the Minolta Chromameter (r = 0.72).The Scarbase Duo® is a reliable and objective scar assessment tool, which is specifically designed for burn scars. However, for clinical use, standardised measurement conditions are recommended.