IGA Score: Atopic Dermatitis, Eczema, Psoriasis, Acne, Prurigo Nodularis, Seborrheic Dermatitis

IGA Score Dermatology:

• What is IGA Score Dermatology?
• Atopic Dermatitis
• Eczema
• Psoriasis
• Acne
• Prurigo Nodularis
• Seborrheic Dermatitis

What is IGA Score Dermatology?

The Investigator’s Global Assessment (IGA) score is a standardized dermatology rating scale used to evaluate the severity of skin diseases. It is widely applied in clinical practice and research to measure treatment response and disease progression. The IGA score typically ranges from 0 to 4 or 0 to 5, depending on the version used. A score of 0 represents clear skin, while higher values represent increasing severity. The scale assesses visual signs such as erythema, scaling, papules, induration, and overall lesion extent.

The IGA score is popular because it is simple, reproducible, and easy to apply across different dermatologic conditions. It provides clinicians with an objective framework to determine whether a treatment is effective and helps in making therapeutic decisions. In clinical trials, the IGA score is often used as a primary endpoint, making it essential for evaluating new therapies for chronic inflammatory skin disorders.

Atopic Dermatitis

The IGA score is most commonly used for atopic dermatitis (AD)

Atopic dermatitis patients with moderate-to-severe symptoms often undergo biologic therapy, topical steroids, or systemic immunomodulators. The IGA score assists in determining treatment escalation or tapering. For example, biologics like dupilumab often use IGA improvement as a clinical endpoint. The consistency of the scoring system ensures reliable assessment, even when different clinicians evaluate the same patient.

Eczema

In general eczema, including nummular eczema and irritant dermatitis, the IGA score helps clinicians quantify flare severity. Since eczema can vary widely in presentation, the IGA score focuses on universal signs such as dryness, redness, crusting, and lichenification. Mild eczema usually scores 1–2, whereas significantly inflamed, thickened, or weepy lesions score 3–4.

Using IGA scoring helps track response to treatments such as topical corticosteroids, moisturizers, calcineurin inhibitors, and phototherapy. It also allows for documenting improvement during follow-up visits or comparing treatment modalities. Eczema patients often experience fluctuating severity, making a standardized scoring system like IGA valuable for long-term management.

Psoriasis

For psoriasis, the IGA score assesses plaque features such as erythema, thickness, and scaling. While PASI (Psoriasis Area and Severity Index) is more detailed, IGA remains valuable in clinical practice for its simplicity. A typical psoriasis IGA scale ranges from 0 (clear) to 5 (very severe). Mild plaques may score 1–2, while thick, scaly, and widespread lesions score 4–5.

The IGA is frequently used in biologic therapy studies, where endpoints such as IGA 0/1 are needed to meet FDA and EMA standards for improvement. This allows easier comparison of drugs like TNF-alpha inhibitors, IL-17 inhibitors, and IL-23 inhibitors. In clinical visits, IGA is helpful for quick assessment and treatment planning without calculating body surface area or plaque thickness manually.

Acne

The IGA score for acne helps classify the severity of comedones, papules, pustules, and nodules. Acne-specific IGA scales often range from 0–4, where 0 means “clear,” 1 means “almost clear,” 2 represents mild acne, 3 moderate, and 4 severe. This scoring method provides a fast overview of acne severity without needing lesion counts.

The acne IGA is particularly useful in clinical trials evaluating topical retinoids, benzoyl peroxide combinations, antibiotics, and isotretinoin. It helps dermatologists decide whether to escalate therapy or maintain current regimens. Because acne can vary in appearance across the face, chest, and back, the IGA score offers a simplified yet reliable way to measure overall improvement.

Prurigo Nodularis

Prurigo nodularis (PN) IGA scoring is used to evaluate nodule thickness, excoriations, hyperkeratosis, and inflammation. PN-specific IGA scales usually rate disease severity from 0 (no active nodules) to 4 (severe nodules with intense itching and inflammation). Given the chronic and highly pruritic nature of PN, IGA provides an important standardized measure for monitoring disease activity.

In newer PN treatments—including biologics such as dupilumab or nemolizumab—IGA improvement is a primary endpoint. Because PN often involves multiple nodules across the arms, legs, and trunk, a simple severity scoring scale like IGA helps clinicians track response and adjust therapy. It is also helpful when documenting baseline severity before initiating long-term treatments.

Seborrheic Dermatitis

For seborrheic dermatitis, the IGA score focuses on redness, scaling, and distribution in areas such as the scalp, eyebrows, nasolabial folds, ears, and chest. Severity levels range from clear (0) to severe (4), depending on how much erythema, flaking, and irritation are present. Mild seborrheic dermatitis may present with light scaling, while severe cases involve thick plaques, inflammation, and discomfort.

The IGA score is used in studies evaluating antifungal treatments like ketoconazole, ciclopirox, and zinc pyrithione, as well as anti-inflammatory agents. Clinically, it helps determine whether a patient needs topical therapy, combination therapy, or maintenance treatment. Seborrheic dermatitis tends to be chronic and relapsing, so consistent scoring improves long-term management and follow-up documentation.