The Global Hidradenitis Suppurativa Atlas Methodology: Combining Global Proportions in a Pooled Analysis.

INTRODUCTION: Data concerning the global burden of hidradenitis suppurativa (HS) are limited. Reported prevalence estimates vary between 0.0003% and 4.1%, and data from various geographical regions are still to be collected. Previously reported prevalences have been limited by the methodological approach and source of data. This has resulted in great heterogeneity as prevalence data from physician-diagnosed cases poorly match those of self-reported apparent HS disease. METHODS: The Global Hidradenitis Suppurativa Atlas (GHiSA) introduces an innovative approach to determine the global prevalence of HS. This approach involves using a previously validated questionnaire to screen apparently healthy adults accompanying a patient to a non-dermatological outpatient clinic visit in a hospital or a private/family medicine clinic. The screening questionnaire (i.e., the index test) is combined with a subsequent physician-based in-person validation (i.e., the reference standard) of the participants who screen positive. Approximately ten percent of the screen-negative participants are also clinically assessed to verify the diagnostic precision of the test. The local prevalence (pi) will be estimated from each country that submits the number of patients who are HS positive according to the index test and clinical examination (n), and the corresponding total number of observations (N). CONCLUSION: The GHiSA Global Prevalence studies are currently running simultaneously in 58 countries across six continents (Africa, Europe, Australia, North America, South America, and Asia). The goal of the combined global proportion is the generation of a single summary (i.e., proportional meta-analysis), which will be done after a logit transformation and synthesized using a random-effects model. The novel standardization of the Global Prevalence Studies conducted through GHiSA enables direct international comparisons, which were previously not possible due to substantial heterogeneity in past HS prevalence studies.

Prevalence of Hidradenitis Suppurativa in an African Population: Validation of a Screening Questionnaire in Lagos, Nigeria.

BACKGROUND: Epidemiologic hidradenitis suppurativa (HS) studies from Africa are lacking. This study aimed at uncovering the prevalence of HS in Lagos, Nigeria, to validate an HS screening questionnaire, and to contribute to the Global Hidradenitis Suppurativa Atlas (GHiSA). METHODS: This was a cross-sectional study of 802 healthy adults accompanying their relations to the outpatient clinic of Family Medicine and Ophthalmology at the Lagos State University Teaching Hospital in Lagos, Nigeria, following ethical approval. Verbal and written consents were obtained prior to inclusion of study participants. The study was conducted using a validated screening questionnaire. Screen-positive and randomly selected screen-negative participants were clinically examined. Severity was categorized using the Hurley score. RESULTS: The prevalence of HS in the sample was 2.2% (18/802; 95% CI: 1.4-3.5%) with no gender predominance. The mean age in the HS group was 34 years (IQR 28-42) and the median body mass index (BMI) of the HS patients was 27.0 (IQR 21.4-28.6). There was no significant difference in BMI between the HS and control group. The screening questionnaire had a sensitivity of 1 (18/18), specificity of 0.8 (20/25), positive predictive value of 0.8 (18/23), and a negative predictive value of 1 (20/20). The axilla was the predominant site of affection (66.7%), and all HS patients were classified as mild disease (Hurley score 1). CONCLUSION: The prevalence of HS in Lagos, Nigeria, was 2.2% and, in this population, BMI did not appear to be a risk factor. The axilla was the most affected site, and all patients had a mild disease severity (Hurley score 1). Finally, the HS screening questionnaire is a suitable tool in population surveys.

Long-Term Follow-Up after Radiotherapy of Hidradenitis Suppurativa.

BACKGROUND: Patients with hidradenitis suppurativa (HS) are still often disappointed with the current treatments offered and there is a clear demand for more effective options. Since the late 1990s there has been a revival in the use of radiotherapy (RT) for different benign diseases, including HS. During the past 20 years one case series and some scattered case reports have described promising results of RT. OBJECTIVES: To evaluate the long-term efficacy of RT in early-stage HS. METHODS: A postal survey-based long-term follow-up with simple factual questions of partly retrospective and partly contemporary characteristics was performed. Sixty-four patients (96 axillae), diagnosed with mild to moderate HS were irradiated with a orthovoltage unit with 100 kV, 3 mm Al or 200 kV, 0.5 Cu filtering, respectively. Four to six biweekly fractional doses ranging from 0.75 to 1 Gy up to a total dose of 6 Gy in one series, and in chronic cases followed by four daily fractions of 2 Gy up to a total dose of 14 Gy, were given. Late treatment toxicity and the rate of remission of the disease were evaluated. RESULTS: The overall response rate of the survey was 64.1% with 40.6% (26/64) valid, complete questionnaires. In total, 40 axillae were irradiated in these 26 patients. After a median follow-up of 40 years (range 32-52) complete remission of the lesions occurred in 34 of the 40 sites (85%). None of the 26 patients with 40 irradiated sites reported adverse effects at the time of the survey. CONCLUSIONS: RT appears to be an effective treatment for early and mild HS in the majority of patients. In this case series, no side effects were reported after a median follow-up period of 40 years.

Mechanical forces and Hidradenitis Suppurativa.

The mechanism by which inflammatory skin disease forms localized patterns of lesions is poorly understood. Hidradenitis suppurtiva (HS) is strikingly located to intertriginous areas. These areas are subject to considerable mechanical stress (friction, pressure and shear forces). Koebner phenomenon (KP) describes the appearance of typical skin lesions of a pre-existing dermatosis on previously clear skin following trauma, such as friction, pressure and more often penetrating injury with subsequent scarring. Striae distensae (SD) are a form of dermal scarring and can be considered as a form of inflammation-driven dermal disarray. Ectopic HS lesions may occur as KP due to trauma and locally increased susceptibility consisting of either altered mechanical qualities or inflammation. SD and mechanical stress may thus provide a model for the development of lesions. In the absence of an (animal) model or experiment, two patients are described who show HS (-like) lesions along co-localized with SD. The suggested two-hits model may be necessary for the development of KP in HS, that is that the general susceptibility, conferred by obesity, requires a local susceptibility factor to result in ectopic lesions. Ultimately, if ectopic HS lesions are considered true HS lesions it may be speculated that similar interaction occurs in the naturally stressed skin areas offering a possible explanation of the localized pattern of the disease.

Inflammatory bowel disease is associated with hidradenitis suppurativa: Results from a multicenter cross-sectional study.

BACKGROUND: Hidradenitis suppurativa (HS) is often associated with inflammatory bowel disease (IBD; Crohn's disease or ulcerative colitis). However, the prevalence of IBD in HS patients is unknown. OBJECTIVE: To determine the prevalence of IBD in HS patients, and determine if patients with HS and IBD have a distinct HS phenotype. METHODS: For this multicenter, cross-sectional study, HS patients were asked during their first consultation if they had IBD. The diagnosis of IBD was checked in the medical files, and clinical characteristics were collected. RESULTS: IBD had a prevalence of 3.3% (95% CI 2.3-4.4) in 1076 HS patients. The prevalence of Crohn's disease was 2.5% (95% CI 1.6-3.4) and the prevalence of ulcerative colitis was 0.8% (95% CI 0.3-1.4). HS-IBD patients were less frequently obese (13.9% vs 31.2%, P = .04) than HS-only patients, but there were no differences in gender, family history of HS, disease severity, body areas affected by HS, or smoking status. LIMITATIONS: The prevalence might be underestimated since HS patients might still develop IBD. CONCLUSION: The prevalence of IBD in HS patients (3.3%) is 4-8 times higher than the prevalence in the general northern European population (0.41%-0.74%), however HS-IBD patients do not have a distinct HS phenotype.

Should Hidradenitis Suppurativa Be Included in Dermatoses Showing Koebnerization? Is It Friction or Fiction?

BACKGROUND: The etiology of hidradenitis suppurativa (HS) involves genetic and environmental factors. Well-established associated systemic factors are obesity, smoking, inflammation, and bacteria. Whether localized environmental factors such as friction and pressure may also play a causative role is still unclear. OBJECTIVE: To describe the possible Koebner phenomenon (KP) in HS. METHODS: The case notes on 14 patients with typical HS and additional HS lesions in previously uninvolved skin areas exposed to mechanical stress, e.g., on the abdomen at the level of the waistband, were reviewed with regard to the clinical characteristics of the cohort. RESULTS: All 14 patients (7 females) were obese with a mean BMI of 35.8 (range 30.1-45.0). All patients developed additional ectopic HS lesions at the sites of friction on the convex abdomen. The ectopic lesions were clinically and histopathologically similar to HS. CONCLUSION: 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. 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.

Hidradenitis suppurativa (HS) is associated with low socioeconomic status (SES): A cross-sectional reference study.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic debilitating disease, whereby school attendance and employment can be disturbed. OBJECTIVE: We sought to determine the socioeconomic status (SES) in patients with HS relative to other dermatologic patients, and whether specific clinical HS characteristics correlate with SES. METHODS: For this multicenter cross-sectional reference study, data were collected from patients with HS and sex- and age-matched dermatologic patients in a 1:2 ratio. SES was derived from the mean household income and real estate value on a neighborhood level. RESULTS: The SES distribution among 1018 patients with HS was significantly lower than among 2039 age- and sex-matched dermatologic control patients (P < .001). In patients with HS a low SES was associated with axillary involvement (odds ratio 1.42, P = .04), high body mass index (odds ratio 1.03, P = .003), and lower age at inclusion (odds ratio 0.98, P = .001), but not with disease severity or age of disease onset. LIMITATIONS: SES was based on postal code level and causality cannot be determined. CONCLUSION: In the general population, low SES is associated with an unhealthy lifestyle such as smoking and obesity. Therefore, low SES might be a risk factor for developing HS.

Intralesional triamcinolone for flares of hidradenitis suppurativa (HS): A case series.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the hair follicle. Standard practice of managing acute flares with corticosteroid injection lacks scientific evidence. OBJECTIVE: We sought to assess the outcomes of routine treatment using intralesional triamcinolone (triamcinolone acetonide 10 mg/mL) in the management of acute flares in HS. METHODS: This was a prospective case series evaluating the effect of intralesional corticosteroids for alleviation of acute flares in HS. Physician- and patient-reported outcomes were noted. RESULTS: Significant reductions in physician-assessed erythema (median score from 2-1, P < .0001), edema (median score from 2-1, P < .0001), suppuration (median score from 2-1, P < .0001), and size (median score from 3-1, P < .0001) was demonstrated at follow-up. A significant difference in patient-reported pain visual analog scale scores occurred after 1 day (from 5.5-2.3, P < .005) and from day 1 to day 2 (from 2.3-1.4, P < .002). LIMITATIONS: Small study size, open single-arm design, and short follow-up time are the limitations of this study. CONCLUSION: Intralesional injection of corticosteroids is perceived as beneficial by physicians and patients in the management of HS flares by reducing pain after 1 day and signs of inflammation approximately 7 days later.

The ABC of Hidradenitis Suppurativa: A Validated Glossary on how to Name Lesions.

BACKGROUND: The precise clinical description of skin lesions observed in some patients with hidradenitis suppurativa (HS) can be extremely difficult. OBJECTIVE: Establishing a validated glossary of terms allowing the best possible description of lesions observed in HS patients. MATERIAL AND METHODS: Five international experts of HS were to assess a series of 25 photos representing typical lesions of this disorder. For each photo, the experts were asked whether naming of the lesions was possible or not and, if yes, by using which noun. Agreement of their responses was calculated using Fleiss's kappa index. Using a Delphi strategy, photos with disagreement were discussed, and photos were reevaluated on the next day. In case of agreement on the impossibility of naming some clinical situations, new terms, to be included into the glossary, were agreed upon. RESULTS: After the first round of photos, agreement between the experts was poor with a kappa index of only 0.33 (95% CI 0.22-0.46). After extensive discussion of cases with disagreement, the kappa index increased on day 2 to 0.75 (95% CI 0.60-0.87), allowing to conclude on good interobserver agreement on terminology. Furthermore, a few clinical situations were identified in which naming with established semantics is so far not possible. For these situations, the terms 'multicord', 'multipore', 'multitunnel' and 'retraction' were defined. DISCUSSION: This is the first validation of clinical terms used to describe lesions in patients with HS. This should be helpful in better defining the clinical phenotypes observed in this disorder.

New and traditional surgical approaches to hidradenitis suppurativa.

When the prevention of new lesions fails and when medical therapy of established and growing lesions is ineffective, surgery is the accepted method of dealing with hidradenitis suppurativa/acne inversa. The rationale and preferred techniques of mini-unroofing using a biopsy punch, deroofing using scissors, electrosurgery or laser, and classical wide excision and closure are discussed. The situation in which incision and drainage is considered for temporary pain relief would be best considered an opportunity for deroofing, as illustrated in the accompanying online videos.

Correlation of early-onset hidradenitis suppurativa with stronger genetic susceptibility and more widespread involvement.

BACKGROUND: The reported mean age of onset of hidradenitis suppurativa (HS) is between 20 and 24 years. Prepubertal onset is thought to be rare. OBJECTIVE: We sought to determine the prevalence of early-onset HS and to compare clinical characteristics between early-onset and normal-onset HS in a retrospective study. METHODS: Data were collected from 855 patients with HS. Early-onset HS was defined as onset before the thirteenth birthday. Clinical characteristics were analyzed in relation to the age of onset. RESULTS: In all, 66 patients (7.7%) reported early-onset HS. A family history for HS was significantly higher in early-onset patients (55.6% vs 34.2%; odds ratio 2.1, 95% confidence interval 1.2-3.6, P = .006). They developed inflammatory lesions at more body sites than patients with normal-onset HS (odds ratio 3.0, 95% confidence interval 1.8-4.9, P < .001). Distribution of the Hurley stages of severity showed no differences between the 2 groups (odds ratio 1.1, 95% confidence interval 0.7-1.8, P = .72). LIMITATIONS: Some data were based on patient-reported information. CONCLUSION: Early-onset HS occurs more frequently than previously believed. Patients with early-onset HS often report a family history for HS and develop lesions at more body sites.

Hidradenitis suppurativa: a retrospective study of 846 Dutch patients to identify factors associated with disease severity.

BACKGROUND: Few comprehensive studies exist on the epidemiology of hidradenitis suppurativa, a very distressing skin disease. OBJECTIVE: We sought to identify disease-related factors associated with severity, sex, and family history. METHODS: Ordinal logistic regression was used in 846 consecutive Dutch patients with hidradenitis suppurativa to calculate odds ratios (ORs) for severity according to Hurley. Sex and family history were compared using Student t test and χ(2) test. RESULTS: In total, 45.5% of the patients had Hurley I, 41.5% had Hurley II, and 13.0% had Hurley III. Severity was associated with male sex (OR 2.11; P < .001), disease duration (OR 1.03; P < .001), body mass index (OR 1.03; P = .01), smoking pack-years (OR 1.02; P = .001), and axillary (OR 2.24; P < .001), perianal (OR 1.92; P < .001), and mammary lesions (OR 1.48; P = .03). Women had earlier onset, more inguinal and mammary lesions, and more frequent family history for hidradenitis suppurativa. Men more commonly had gluteal, perianal, and atypical lesions, and a history of severe acne. Patients with a family history had earlier onset, longer disease duration, a history of severe acne, more extensive disease, and were more often smokers. LIMITATIONS: Some parameters were patient-reported. CONCLUSION: The severity risk factors identified in this study could help physicians to select patients who need close monitoring and who would benefit from early, aggressive therapy.

Hidradenitis suppurativa: viewpoint on clinical phenotyping, pathogenesis and novel treatments.

Hidradenitis suppurativa (HS) is an inflammatory, debilitating follicular skin disease with recurring flare-ups. The painful, deep-seated, inflamed lesions in the inverse areas of the body cause severe discomfort, and hence, serious psycho-social and economic costs. HS is common, but often misdiagnosed and mechanistically poorly understood. Furthermore, HS is notoriously difficult to treat resulting in a high unmet medical need. To provoke debate, rational experimentation and initiate strategic studies, we here present a concise viewpoint on seven topics: the diagnosis of HS, the role of mechanical friction, the critical importance of accurate clinical subgrouping, smoking and obesity, the role of bacteria, and our comprehensive view on HS pathogenesis with a central role for keratin clearance, and novel treatment approaches.