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IHS4

IHS4: International HS Severity Score System for bedside clinical grading.

Nodules

0
Weight: 1 Point

Abscesses

0
Weight: 2 Points

Tunnels

0
Weight: 4 Points

Awaiting Data

Enter the count of inflammatory nodules, abscesses, and draining tunnels to compute the global IHS4 score.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

When to Use

Quantifying the dynamic severity of Hidradenitis Suppurativa (HS) at baseline and during follow-up.
Evaluating clinical response to systemic or biologic therapies.
Superior to Hurley staging for monitoring continuous treatment response, as Hurley is static and largely defined by irreversible scarring.

How it Works

Scoring Algorithm

Nodules (inflammatory): 1 point each
Abscesses: 2 points each
Draining fistulas (tunnels/sinuses): 4 points each
IHS4 Score = (Number of Nodules × 1) + (Number of Abscesses × 2) + (Number of Draining Fistulas × 4)

Clinical Pearls

Severity Categories

≤ 3: Mild
4 - 10: Moderate
≥ 11: Severe

Clinical Pearls

IHS4 specifically heavily weights draining fistulas (4 points), acknowledging their disproportionate impact on patient morbidity and quality of life compared to nodules.
Non-inflammatory lesions (like inactive scars or comedones) are intentionally excluded from the score.
A clinically meaningful response in trials is often defined as an IHS4-50 (a 50% reduction in the total score from baseline).

Next Steps

Management Shift

01
Mild (≤3): First-line therapy includes topical clindamycin, resorcinol, or limited courses of oral tetracyclines.
02
Moderate (4-10): Escalate to combination oral antibiotics (clindamycin/rifampin) or consider systemic biologics (Adalimumab).
03
Severe (≥11): Strongly indicates the need for systemic biologics (e.g., Adalimumab, Secukinumab, Bimekizumab) and multidisciplinary surgical planning for extensive fistulizing disease.

The Evidence

Primary Reference

Development and validation of the International Hidradenitis Suppurativa Severity Score System (IHS4), a novel dynamic scoring system to assess HS severity.

Zouboulis CC et al. • Br J Dermatol.. 2017;177(5):1401-1409. Derived and validated the score to bridge the gap between static staging (Hurley) and clinical trial endpoints.

View Source

External Links

Origins & History

Dr. Christos C. Zouboulis and the European Hidradenitis Suppurativa Foundation (EHSF) developed IHS4 to provide clinicians with a simple, continuous severity metric that captures dynamic disease activity.

Last Comprehensive Review: 2026-07-17

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