Table 1.

Main tools commonly used in the assessment of HS severity and disease burden.

Clinical and Research Settings
International Hidradenitis Suppurativa Severity Score System (IHS4)
IHS4 (point) = -Number of nodules × 1 -Number of abscesses × 2 -Number of draining tunnels (fistulae/sinuses) × 4
Mild HS: ≤3 points Moderate HS: 4–10 points Severe HS: ≥11 points
Advantages		Limitation
-It is a dynamic HS score. -It is simple to calculate. -Early identification of patients with moderate and severe disease, based on the presence of a draining tunnel (fistula/sinus) which is sufficient to classify an HS patient as at least moderate case.		-It is exclusively physician-based.
Hurley Staging System
Stage	I	II	III
Abscess	Single or multiple	Single or multiple, widely separated, recurrent	Diffuse or near-diffuse involvement
Sinus tract	–	+	Multiple interconnected
Cicatrization	–	+	+
Area			Entire area
Advantages		Limitation
-It was originally designed for selection of the appropriate treatment modality in a specific body location (medical therapy for Hurley stage I, local surgery for Hurley stage II, and wide surgical excision for Hurley stage III). -It is reliable for rapid assessment of HS, and it is best for assessing Hurley stage III, meaning whether a patient should be candidate for surgery.		-It is static and it was not designed as a dynamic score for an accurate assessment of the extent of inflammation within each stage.
Hidradenitis Suppurativa Clinical Response—HiSCR
HiSCR is defined by the status of three types of criteria lesions, considering abscesses (fluctuant, with or without drainage, tender or painful), inflammatory nodules (tender, erythematous, pyogenic granuloma lesion), and draining fistulas (sinus tracts, with communications to skin surface, draining purulent fluid). The proposed definition of responders to treatment (HiSCR achievers) is: At least a 50% reduction in ANs; No increase in the number of abscesses; No increase in the number of draining fistulas from baseline.
Advantages		Limitation
-It is the most validated dynamic physical measure for assessing treatment response in RCTs.		-It has lower utility in the clinical setting.
Hidradenitis Suppurativa Physician’s Global Assessment (HS-PGA)
HS-PGA
Clear (score = 0)		0 abscesses, 0 draining fistulas, 0 inflammatory nodules, and 0 non-inflammatory nodules
Minimal (score = 1)		0 abscesses, 0 draining fistulas, 0 inflammatory nodules, and presence of non-inflammatory nodules
Mild (score = 2)		0 abscesses, 0 draining fistulas, and 1–4 inflammatory nodules; or 1 abscess or draining fistula and 0 inflammatory nodules
Moderate (score = 3)		0 abscesses, 0 draining fistulas, and 1 ≥ 5 inflammatory nodules; or 1 abscess or draining fistula and ≥1 inflammatory nodule; or 2–5 abscesses or draining fistulas and <10 inflammatory nodules
Severe (score = 4)		2–5 abscesses or draining fistulas, and ≥10 inflammatory nodules;
Advantages		Limitation
-It is a dynamic HS score. -It is simple to calculate.		-It is lower utility in the clinical setting compared to RCTs.
Patient-Reported Outcomes
Dermatology Life Quality Index (DLQI Score)
DLQI Total score
0–1		No effect on patient’s life
2–5		Small effect on patient’s life
6–10		Moderate effect on patient’s life
11–20		Very large effect on patient’s life
21–30		Extremely large effect on patient’s life
Advantages		Limitation
-It is a valuable adjunct and straightforward to perform in clinical settings.		-It is a skin-specific questionnaire that poorly considers the pain/discomfort dimension, which is dominant in HS.
Pain Visual Analog Scale (Pain VAS) and Numeric Rating Scale (NRAS) for Pain
The pain VAS is a continuous scale comprised of a horizontal (HVAS) or vertical (VVAS) line, usually 10 cm in length, anchored by 2 verbal descriptors, one for each symptom extreme. The NRAS for pain is a single 11-point numeric scale, which can be administered verbally or graphically. Response options/scale. For pain intensity, both scales are most commonly anchored by “no pain” (score of 0) and “pain as bad as it could be” or “worst imaginable pain” (score of 10).
Advantages		Limitation
-VAS and NRAS are valuable adjuncts and straightforward to perform in clinical settings. -VAS and NRAS can be used to measure worst, least, or average pain over the last 24 h, or during the last week.		-While the VAS can be quick to use, it is not as practical as the Numerical Rating Scale (NRS) as it requires clear vision, dexterity, paper, and pen.