Eczema Area and Severity Index (EASI)

DESCRIPTION:
The Eczema Area and Severity Index is a widely used tool to assess severity of atopic dermatitis (eczema). The EASI evaluation involves assessing 4 body regions—head, trunk, and upper and lower extremities—across 2 domains of disease activity, percent of body surface affected, and the intensity of lesional skin into one composite score. Percent of body surface affected is based on a
7-point scale and intensity/severity is based on a 4-point scale consisting of values assigned to erythema, edema/papulation, excoriation, and lichenification.^1-3

DISEASE STATES: 
Atopic dermatitis

VALIDATED USES: 
Assessment, screening, treatment monitoring

ADMINISTRATION METHOD:
Clinician

COMMONLY USED IN:
Clinical trials, research, clinical practice

DETAILED DESCRIPTION:
Originally created in 1998 and subsequently validated, the EASI assessment tool was developed to meet the needs of researchers who required a standardized evaluation tool for assessing the severity of atopic dermatitis in clinical studies.^1,2 The EASI was designed by modifying the existing Psoriasis Area and Severity Index scoring system.² After an extensive review of more than 16 instruments, the Harmonising Outcome Measures for Eczema (HOME) initiative identified the EASI as the recommended core instrument for measuring signs in all AD clinical trials.^3,4

EASI quantifies disease severity as one easy-to-use composite score that may range from 0.0 (no disease activity) to 72.0 (the most severe disease).^1-3 Because there is one value for disease severity, clinical trials often compare baseline EASI scores with clinical endpoint EASI scores. These clinical trial endpoints are typically represented as a proportion of patients who achieve a predetermined reduction in EASI score, or disease severity:

• EASI 100: Proportion of subjects achieving 100% reduction in EASI score 
• EASI 90: Proportion of subjects achieving ≥90% reduction in EASI score 
• EASI 75: Proportion of subjects achieving ≥75% reduction in EASI score

The EASI evaluation involves assessing the percentage of body surface area affected by atopic dermatitis (eczema) and assigning a score for each body region based on intensity of lesions. The score for each region is then multiplied by the percentage of body surface area affected, and the scores for all regions are added together to give the final EASI score. The 4 main body areas are: head (h), trunk (t), upper extremities (u), and lower extremities (l).^1-3

The EASI score for each body region is obtained by multiplying the sum of the severity scores by the area score, then multiplying the result by the constant weighted value assigned to that body region.

PASI score is calculated using the formula:^1-3*

EASI = 0.1(Eh + EPh + EXh+ Lh)Ah + 0.2(Eu + EPu + EXu+ Lu)Au + 0.3(Et + EPt + EXt+ Lt)At + 0.4(El + EPl + EXl+ Ll)Al

E = erythema; EP = edema/papulation; EX = excoriation; L = lichenification.

*Other specific body parts assignments are: neck = head domain; buttocks = lower extremities; axillae and genitals = trunk; the inguinal canal separates the trunk and legs anteriorly.

EASI SCORING

Note: Half points may be used between points 1 and 3 (e.g., 1.5 and 2.5 but not 0.5).

*For patients ≤7, weighting factor for head = 20% (0.2) and lower limbs = 30% (0.3).

EASI INTERPRETATION

VALIDITY:
The validity of EASI has been investigated across multiple studies and in thousands of participants.^2,5 Hanifin et al. 2001 found that EASI demonstrated good to excellent intra-evaluator and inter-evaluator reliability in assessing AD.² Schmitt et al. 2013 also determined that EASI is among one of the best instruments available to measure clinical signs of AD, having high content validity, construct validity, internal consistency, and sensitivity to change.

LIMITATIONS:
Interrater and intrarater reliability may vary and some studies suggest the same investigator should perform the EASI throughout a trial whenever possible.^4,5 Pigmented skin assessments may be challenging, especially when measuring erythema.⁶

This resource is intended for educational purposes only and is intended for US healthcare professionals. Healthcare professionals should use independent medical judgment. All decisions regarding patient care must be handled by a healthcare professional and be made based on the unique needs of each patient.

References: 1. Tofte S, Graeber M, Cherill R, Omoto M, Thurston M, Hanifin J. Eczema area and severity index (EASI): a new tool to evaluate atopic dermatitis. J Eur Acad Dermatol Venereol.1998;11:S197. doi:10.1016/S0926-9959(98)95291-6 2. Hanifin JM, Thurston M, Omoto M, Cherill R, Tofte SJ, Graeber M. The eczema area and severity index (EASI): assessment of reliability in atopic dermatitis. EASI Evaluator Group. Exp Dermatol. 2001;10(1):11-8. doi:10.1034/j.1600-0625.2001.100102.x 3. Hanifin JM, Baghoomian W, Grinich E, Leshem YA, Jacobson M, Simpson EL. The Eczema Area and Severity Index-a practical guide. Dermatitis. 2022;33(3):187-192. doi:10.1097/DER.0000000000000895 4. Schmitt J, Spuls PI, Thomas KS, et al. The Harmonising Outcome Measures for Eczema (HOME) statement to assess clinical signs of atopic eczema in trials. J Allergy Clin Immunol. 2014;134(4):800-807. doi:10.1016/j.jaci.2014.07.043 5. Schmitt J, Langan S, Deckert S, et al. Assessment of clinical signs of atopic dermatitis: a systematic review and recommendation. J Allergy Clin Immunol. 2013;132(6):1337-1347. doi:10.1016/j.jaci.2013.07.008 6. Ben-Gashir MA, Hay RJ. Reliance on erythema scores may mask severe atopic dermatitis in black children compared with their white counterparts. Br J Dermatol. 2002;147(5):920-925. doi:10.1046/j.1365-2133.2002.04965.x