Background: Pruritus is still a forgotten aspect of hidradenitis suppurativa (HS) and, to date, has never been adequately studied.
Objective: The aim of this study was to determine the prevalence, and explore the characteristics, of pruritus in a well-defined cohort of HS patients.
Setting: An academic hospital-based cross-sectional study in The Netherlands.
Methods: A numerical rating scale (NRS, 0-10) was used to determine the prevalence of HS-related itch (NRS score ≥3). Candidate predictors for pruritus were subsequently determined using logistic regression models, and the impact of pruritus was assessed using a modified five-dimensional (5-D) itch scale. Associated serological and histological markers of pruritus were (semi-)quantitatively investigated in a subpopulation.
Results: The prevalence rate of pruritus in 211 HS patients was 57.3%, with a mean NRS score of 6.1 ± 2.0. Patients with a pruritus NRS score ≥3 had more HS-affected body sites than patients with a score <3 (p < 0.001). The occurrence of a pruritus NRS score ≥3 was associated with Hurley III disease (odds ratio [OR] 7.73; p = 0.003) and pain (OR 1.34; p < 0.001). Pruritus affected sleep and activities of daily living (ADL) in the majority of cases, with an associated modified 5-D itch score of 13.7 ± 3.6 (on a scale from 5 to 25) in 52 HS patients. Histological examination showed eosinophilic granulocytes were present in 25% (2/8) of the perilesional skin and 63% (10/16) of the lesional skin, while a perineural infiltrate was found in 25% (2/8) and 69% (11/16) of the perilesional and lesional skin, respectively.
Conclusion: Pruritus is a frequent but underreported symptom in patients with HS. Its moderate to severe intensity and significant impact on daily activities have great potential to impair patients' quality of life.
Keywords: Atopic Dermatitis; Chronic Urticaria; Hidradenitis Suppurativa; Minimal Clinically Important Difference; Numerical Rating Scale.