ISTANBUL, TURKEY – Patients with hidradenitis suppurativa have a sharply increased prevalence of the metabolic syndrome, according to the first case-control study to examine the relationship.
Metabolic syndrome is known to be associated with increased cardiovascular risk, which may be particularly high in patients with hidradenitis suppurativa (HS), a dermatologic disease with an estimated prevalence of 1%-4%, because they develop metabolic syndrome at a much younger age than do individuals without the dermatologic disease, Dr. Wolfram Sterry said at the annual congress of the European Academy of Dermatology and Venereology.
He presented highlights from a single-center, case-control study that comprised 80 patients with HS with a mean 12-year disease duration and 100 age- and gender-matched controls. Patients’ mean age was 40 years (PLoS One 2012 [doi:10.1371/journal.pone.0031810]).
Dr. Wolfram Sterry
The prevalence of metabolic syndrome was 40% in the HS group and 13% in controls, for an adjusted 4.5-fold increased likelihood, reported Dr. Sterry, professor and chairman of the department of dermatology at Charité University Hospital, Berlin.
Of the five metabolic derangements used in defining the metabolic syndrome, four were significantly more prevalent in subjects with HS. They were 5.9-fold more likely than were matched controls to have central obesity, 4.1-fold more likely to have hyperglycemia, 4.6-fold more likely to have low HDL cholesterol, and 2.2-fold more likely to be hypertriglyceridemic. Hypertension was present in 48% of HS patients and 35% of controls, a difference that did not achieve statistical significance.
Of note, HS patients with metabolic syndrome had more pronounced metabolic abnormalities than did controls with metabolic syndrome. While the definition of metabolic syndrome requires the presence of at least three of five metabolic alterations, half of all HS patients with metabolic syndrome met four or more of the criteria, compared with 39% of controls.
Moreover, metabolic syndrome occurred at a much younger age in subjects with HS than is typical in the general population or than was seen in controls. Indeed, 40% of HS patients under age 35 had metabolic syndrome, compared with none of the matched controls. Thus, the odds ratio for metabolic syndrome in HS patients aged 34 years or less was increased more than 20-fold compared with controls, while in the 35- to 44-year-old age group it was increased 6.2-fold, and in HS patients aged 45 and older it was 2-fold higher.
An increased prevalence of metabolic syndrome also has been documented in patients with psoriasis. But the prevalence of metabolic syndrome appears to be higher in HS patients and the metabolic disorder occurs at an earlier age than in psoriasis.
There was no correlation between duration or severity of HS and the prevalence of metabolic syndrome, according to Dr. Sterry. That’s an important message for physicians who see patients with the skin disease because it means such patients should be evaluated for metabolic syndrome early on, even if they have only moderate skin disease. After all, the elements of the metabolic syndrome are modifiable cardiovascular risk factors.
The lack of correlation between HS severity or duration and metabolic syndrome prevalence also has implications for the mechanism underlying the increased risk of metabolic syndrome in HS. When Dr. Sterry and coworkers compared the levels of metabolic syndrome parameters in the 42 patients with prior surgical treatment of their HS to the 38 patients who had not undergone surgery, they found no significant differences even though the surgical patients presumably had less inflammatory load. This led them to speculate that chronic inflammation may not be the major driver of the metabolic abnormalities in HS patients.
"It must be that a genetic predisposition for metabolic syndrome then induces the development of acne inversa [hidradenitis suppurativa] in predisposed individuals," Dr. Sterry said.
The proposed mechanism involves metabolic syndrome–induced poor blood circulation in the intertriginous axillary, perianal, and inguinal skin where HS most often occurs, with resultant increased interleukin-10 production by CD4-positive T cells. Interleukin-10, in turn, inhibits keratinocyte production of interleukins-20 and -22, which induce antimicrobial proteins in the skin. This would set the stage for HS, which is characterized by bacterial persistence in obstructed hair follicles, nodules, and fistulating sinuses.
Of course, this is speculation, Dr. Sterry was quick to acknowledge.
"Acne inversa is also known as hidradenitis suppurativa, apocrine acne, pyoderma fistulans significa ... If a disease has that many names, that’s always a sign that we don’t know too much about it," the dermatologist observed.
In a separate study presented at the EADV, investigators found that the most common comorbid conditions in a cohort of 154 patients with HS enrolled in a clinical trial of adalimumab (Humira) therapy were depression as defined by a score of 10 or more on the Patient Health Questionnaire–9, which had a prevalence of 42%; severe obesity marked by a body mass index of at least 40 kg/m2, present in 28% of patients; and uncontrolled hypertension, which was present in 27%. However, the investigators did not look at metabolic syndrome.