How EASI is calculated
For each region, add the four severity signs, multiply by the area score, then multiply by that region’s share of body surface area. The four regional results are summed.
EASI = Σ (E + I + Ex + L) × area score × region multiplier
The four signs
Erythema, induration/papulation, excoriation and lichenification, each graded 0 (none), 1 (mild), 2 (moderate) or 3 (severe).
Half steps of 1.5 and 2.5 are available on the smaller buttons between the whole numbers; there is no 0.5. Note the published instrument uses whole numbers, so a score recorded with half steps is not strictly EASI as validated.
Region multipliers
The weighting changes for children under 8, because the head is proportionally larger and the legs smaller.
| Region | Adult and child 8+ | Under 8 years |
|---|
| Head and neck | 0.1 | 0.2 |
| Trunk | 0.3 | 0.3 |
| Upper extremities | 0.2 | 0.2 |
| Lower extremities | 0.4 | 0.3 |
Area score
The percentage of each region involved converts to a 0–6 score.
| Involvement | Area score |
|---|
| 0% | 0 |
| 1–9% | 1 |
| 10–29% | 2 |
| 30–49% | 3 |
| 50–69% | 4 |
| 70–89% | 5 |
| 90–100% | 6 |
Interpreting the total
The bands below follow Leshem and colleagues (2015), who anchored EASI against the Investigator’s Global Assessment.
| EASI | Severity |
|---|
| 0 | Clear |
| 0.1 – 1.0 | Almost clear |
| 1.1 – 7.0 | Mild |
| 7.1 – 21.0 | Moderate |
| 21.1 – 50.0 | Severe |
| 50.1 – 72.0 | Very severe |
What counts where
The neck is scored with the head. The axillae and groin are scored with the trunk. The buttocks are scored with the lower extremities. Hands belong to the upper extremities and feet to the lower extremities.
References
Hanifin JM, Thurston M, Omoto M, et al. The eczema area and severity index (EASI): assessment of reliability in atopic dermatitis. Exp Dermatol 2001;10:11–18.
Leshem YA, Hajar T, Hanifin JM, Simpson EL. What the Eczema Area and Severity Index score tells us about the severity of atopic dermatitis. Br J Dermatol 2015;172:1353–1357.
