<scp>SALT</scp> Score Cards: Facilitating <scp>SALT</scp> Score Calculation in Alopecia Areata

The severity of alopecia tool (SALT) was developed to quantify severity of alopecia areata (AA) scalp involvement, facilitating assessment of response to treatment in both clinical trials and in clinical practise [1]. At present, a visual aid to assist calculation is available, which uses multiple diagrams of the scalp with their percentage area of the total scalp and suggests the evaluator graph the area of alopecia in order to evaluate the total percentage hair loss. SALT score calculation can be challenging despite this visual aid, due to hair length discrepancy, smaller involved patches individually not scoring a whole number, and incomplete regrowth within patches. We sought to develop a handheld SALT score card to assist with SALT score calculation in both the clinical and research settings. The median head circumference for adult males and females using normative values from growth reference charts is 57 and 55 cm, respectively [2]. The total hair bearing surface area of a scalp of diameter of 57 cm was determined as 630 cm2. Using the calculation (area) A = π r 2 $$ A=\pi {r}^2 $$ , 1% of the total scalp area, that is, 6.3 cm2 equates to a circle of radius 2.83 cm. A transparent business card (Figure 1) was developed with marked circles representing SALT score one (radius 2.83 cm), SALT score two (radius 4 cm), SALT score three (radius 5 cm) and the total card area equalled SALT score 7. Given that the median head circumference for women is two centimetres smaller than that of men, approximation of SALT scores for women using this card differs by −3.5%. The SALT score is calculated by applying the card against each patch of AA, and estimating the area of absent hair against the guides marked on the card (Figures 2 and 3). This is repeated and the total SALT score calculated from the sum of the score from individual patches. Limitations of this study include that validation of this tool against the current standard of practise using visual SALT score calculation has not yet been completed and is required. The SALT score card is currently being used for SALT score calculation in clinical practice and markedly expedites time to estimating the SALT score. In particular it facilitates SALT calculation in individuals with small patches that individually score a low SALT number and would otherwise be difficult to plot on the previously available visual aid. The SALT score card can be easily replicated via manufacturers of transparent business cards for use in Dermatology practises managing AA and in AA clinical trial centres. The authors are happy to distribute technical measurements of the produced card to interested readers for local production. The authors have nothing to report. The authors have nothing to report. R.S.: professional services to Aerotech, AbbVie, AstraZeneca, Akesobio, Amgen, Arcutis, Arena, Ascend, Bayer, Bristol Myers Squibb, Boehringer Ingelheim, Celgene, Coherus Biosciences, Connect, Cutanea, Demira, Eli Lilly, Galderma, GSK, Janssen, LEO Pharma, MedImmune, Merck, MSD, Novartis, Oncobiologics, Pfzer, Regeneron, Reistone, Roche, Samson Clinical, Sanof, Sun Pharma and UCB. The other authors declare no conflict of intrest. The data that support the findings of this study are available from the corresponding author upon reasonable request.