📊 IHS4 Calculator

International Hidradenitis Suppurativa Severity Score System — Zouboulis et al., 2017

Purpose
Dynamic severity scoring of hidradenitis suppurativa using weighted counts of three lesion types.
Population
Adults and adolescents with HS. Applicable at all body sites, all Hurley stages.
Formula
IHS4 = (1 × IN) + (2 × AB) + (4 × DT)
Severity thresholds
Mild ≤ 3 · Moderate 4–10 · Severe ≥ 11
🔢 Lesion Count

Count all active lesions across all affected body sites.

Inflammatory nodules
Weight × 1
0
Abscesses
Weight × 2
0
Draining tunnels / fistulas
Weight × 4
0
📋 Classic Hurley Staging — Reference

Static anatomical classification. Use IHS4 to quantify severity within each stage.

Stage I
I
Abscess formation
Single or multiple abscesses. No sinus tracts, no cicatrization.
Stage II
II
Recurrent abscesses
Recurrent abscesses with sinus tract formation and cicatrization. Single or multiple, widely separated lesions.
Stage III
III
Diffuse involvement
Diffuse or near-diffuse involvement, or multiple interconnected sinus tracts and abscesses across the entire area.
📚 References
  1. Zouboulis CC, Tzellos T, Kyrgidis A, et al. Development and validation of the International Hidradenitis Suppurativa Severity Score System (IHS4), a novel dynamic scoring system to assess HS severity. Br J Dermatol. 2017;177(5):1401–9.
  2. Zouboulis CC, Prens EP, Sayed CJ, et al. International Hidradenitis Suppurativa Severity Scoring System (IHS4) as a holistic measure of hidradenitis suppurativa disease severity compared with Hurley staging. J Eur Acad Dermatol Venereol. 2024;38:e496–e499.
  3. Hurley H. Axillary hyperhidrosis, apocrine bromhidrosis, hidradenitis suppurativa, and familial benign pemphigus: surgical approach. In: Roenigh RK, Roenigh HH, eds. Dermatologic Surgery. New York: Marcel Dekker; 1989. p. 729–39.
  4. Zouboulis CC, et al. S2k guidelines for the treatment of hidradenitis suppurativa/acne inversa. J Dtsch Dermatol Ges. 2024.
Clinical decision support only. This tool is intended to assist clinical assessment and does not replace professional judgment. Always interpret results in the context of the individual patient.