Hidradenitis Suppurativa Review

Group-Specific Prevalence Rates of Hidradenitis Suppurativa
Hidradenitis suppurativa (HS) in the United States is uncommon, but not rare, according to a recent study by Garg and colleagues published online in JAMA Dermatology.

Researchers conducted a retrospective analysis of more than 48 million patients to establish standardized overall and group-specific prevalence estimates for HS. Of the demographically heterogeneous population-based sample, researchers identified 47,690 patients with HS by October 27, 2016 using electronic health record data. Patients’ sex, age, and race were evaluated to determine the standardized overall point prevalence for HS.

The study found the overall prevalence of HS to be 0.10%, or 98 of 100,000 persons. Of the 47,690 patients identified with the disease, 26.2% were male and 73.8% were female. The prevalence of HS in women was more than twice the size of men, with 137 of 100,000 persons having HS compared with 58 of 100,000 persons. Patients aged 30 to 39 years had the highest prevalence of HS compared with all other age groups (172 per 100,000 persons).

Further examination found that among African Americans, HS was prevalent in 296 of 100,000 persons and in 218 of 100,000 biracial persons, while HS prevalence in white patients was 95 of 100,000 persons.

Though not common in the United States, HS disproportionally affects women, young adults, African Americans, and biracial patients, concluded the researchers. 

—Nina Farrell

Garg A, Kirby JS, Lavian J, Lin G, Strunk A. Sex- and age-adjusted population analysis of prevalence estimates for hidradenitis suppurativa in the United States [published online May 10, 2017]. JAMA Dermatol. doi:10.1001/jamadermatol.2017.0201

Pruritus Related to HS   
Pruritus is a frequent but underreported symptom in patients with HS, according to a recent study by Vossen and colleagues, published in The American Journal of Clinical Dermatology.

The researchers sought to determine the prevalence of pruritus and explore the characteristics of pruritus in a cohort of patients with HS. The academic, hospital-based, cross-sectional study was conducted in The Netherlands. The researchers used a numerical rating scale (NRS, 0-10) to determine the prevalence of HS-related itch (NRS score ≥3). Candidate predictors for pruritus were ascertained using logistic regression models, and the impact of pruritus was assessed using a modified 5-dimensional (5-D) itch scale.

The study demonstrated 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. The occurrence of a pruritus NRS score ≥3 was associated with Hurley III disease and pain. Pruritus affected sleep and activities of daily living 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.

Histologic examination revealed eosinophilic granulocytes were present in 25% (2/8) of the perilesional skin and 63% (10/16) of the lesional skin. A perineural infiltrate was found in 25% (2/8) and 69% (11/16) of the perilesional and lesional skin, respectively.

Pruritus, although frequently underreported as an HS symptom, can occur with moderate to severe intensity and has a significant impact on daily activities. It has great potential to impair patients’ quality of life, the researchers concluded.

Vossen ARJV, Schoenmakers A, van Straalen KR, Prens EP, van der Zee HH. Assessing pruritus in hidradenitis suppurativa: a cross-sectional study [published online April 20, 2017]. Am J Clin Dermatol. doi:10.1007/s40257-017-0280-2

Mechanical Stress Plays Role in Obese Patients With HS
The Koebner phenomenon (KP) may help to explain the distribution of some HS, according to a recent study published in Dermatology. The removal of external stress factors that could lead to KP should be implemented as part of HS treatment, especially in obese patients.

In order to determine if environmental factors including friction and pressure could play a role in HS, researchers examined data from 14 patients with typical HS and additional HS lesions in previously uninvolved areas exposed to mechanical stress. The participants were all obese with a mean body mass index of 35.8, and all developed lesions at sites of friction that were clinically similar to HS.

“Mechanical stress factors or trauma play a role in obese patients with HS. It is suggested that these new induced lesions fit the concept of the KP. This phenomenon seems to occur in the so-called frictional furunculoid type of HS and may explain the unique distribution at certain localizations on the body of this follicular cutaneous eruption,” the researchers concluded. “Removal in an early stage of HS of external stress factors that can lead to the KP should be part of the treatment, especially in obese patients.”

—Michael Potts

Boer J. Should hidradenitis suppurativa be included in dermatoses showing Koebnerization? Is it friction or fiction [published online May 16, 2017]? Dermatology. doi:10.1159/000472252

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