There are 3 main methods of classification for disease severity, these are Hurley staging, the Sartorious score, and the Physician Global Assessment (PGA). These are discussed below;

Hurley Staging

The 3 stage Hurleys classification the disease is the most commonly used staging tool:

  • Stage 1 – Abscess formation, single or a few isolated abscesses without scarring or sinus tracts.

  • Stage 2 – Recurrent abscesses in more than one area and the beginning of the formation of sinus tracts.

  • Stage 3 – Widespread abscesses with many interconnected sinus tracts under the skin. There may be severe scarring and continuous leaking.

Stage 1 is the most common in patients with approx 68% falling into this category, while stage 2 affects approx 28%. 4% of patients will continue to stage 3. Not all people with HS progress to stage 3 - the disease may be controlled so it doesn't progress beyond stage 1 if diagnosed early enough.

Sartorious Score

The Sartorius Hidradenitis Suppurativa Score is made by counting involved regions, nodules and sinus tracts as follows;

  • Region involved (axilla, groin, genital, gluteal, or other inflammatory region left and/or right): 3 points per region involved

  • Number and scores of lesions (abscesses, nodules, fistulas, scars): 2 points for each nodule, 4 points for each fistula, 1 point for each scar, 1 point each for "other"

  • Longest distance between 2 relevant lesions (ie, nodules and fistulas, in each region, or size if only 1 lesion): Less than 5 cm, 2 points; less than 10 cm, 4 points; more than 10 cm, 8 points

  • Lesions clearly separated by normal skin in each region: If yes, 0 points; if no, 6 points

The PGA Score

The six-point hidradenitis suppurativa Physician Global Assessment (PGA) ranges from clear to very severe. It is used in clinical trials to measure clinical improvement in inflammatory nodules, abscesses and draining fistulae. The 6 stages are as follows;

  1. Clear: No inflammatory or non-inflammatory nodules

  2. Minimal: Only the presence of non-inflammatory nodules

  3. Mild: Less than 5 inflammatory nodules or 1 abscess or draining fistula and no inflammatory nodules

  4. Moderate: Less than 5 inflammatory nodules, or 1 abscess or draining fistula and 1 or more inflammatory nodules, or 2-5 abscesses or draining fistulas and less than 10 inflammatory nodules

  5. Severe: 2-5 abscesses or draining fistulas and 10 or more inflammatory nodules

  6. Very severe: More than 5 abscesses or draining fistulas