Global consensus process to establish a core dataset for hidradenitis suppurativa registries.

BACKGROUND: Several registries for hidradenitis suppurativa (HS) already exist in Europe and the USA. There is currently no global consensus on a core dataset (CDS) for these registries. Creating a global HS registry is challenging, owing to logistical and regulatory constraints, which could limit opportunities for global collaboration as a result of differences in the dataset collected. The solution is to encourage all HS registries to collect the same CDS of information, allowing registries to collaborate. OBJECTIVES: To establish a core set of items to be collected by all HS registries globally. The core set will cover demographic details, comorbidities, clinical examination findings, patient-reported outcome measures and treatments. METHODS: Beginning in September 2022, 20 participants - including both clinicians with expertise in HS and patient advocates - from eight countries across three continents participated in a Delphi process consisting of four rounds of voting, with all participants completing each round. A list of potential items for inclusion in the core set was generated from the relevant published literature, including systematic reviews of comorbidities in HS, clinical and examination findings, and epidemiology. For disease severity and progression items, the Hidradenitis SuppuraTiva Core outcome set International Collaboration (HiSTORIC) core set and other relevant instruments were considered for inclusion. This resulted in 47 initial items. Participants were invited to suggest additional items to include during the first round. Anonymous feedback was provided to inform each subsequent round of voting to encourage consensus. RESULTS: The eDelphi process established a CDS of 48 items recommended for inclusion in all HS registries globally. CONCLUSIONS: The routine adoption of this CDS in current and future HS registries should allow registries in different parts of the world to collaborate, enabling research requiring large numbers of participants.

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.

Hidradenitis suppurativa tarda: defining an understudied elderly population.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic, devastating, multifactorial skin disease. Patients generally develop HS after puberty and the prevalence of the disease is assumed to decrease with higher age. Data outside the usual age range are limited, especially for elderly patients. OBJECTIVES: To investigate the prevalence, clinical characteristics and associated comorbidities among the elderly HS population. METHODS: Data were collected through a population-wide survey-based study within the Lifelines Cohort Study in the Netherlands. The clinical characteristics of elderly patients with HS (≥ 60 years) were compared with an adult population (< 60 years) with HS. The comorbidities in elderly patients with HS were compared with those of a non-HS sex- and age-matched elderly population in a 1 : 4 ratio. HS in the elderly was defined as active HS in patients aged 60 years and older. Within the HS elderly group, two subgroups were defined, late-onset HS (HS developed after 60 years of age) and persistent HS (HS developed from a younger age but continuing after 60 years of age). RESULTS: Within the Lifelines cohort 209 elderly patients with HS were identified as well as an adult (< 60 years) group with HS (n = 793) and a non-HS sex- and age-matched control elderly group (n = 810). The prevalence of HS among the elderly bootstrap analysis population was 0.8% [95% confidence interval (CI) 0.4-1.2]. A significantly higher age of HS symptom onset was found compared with the adult HS group: respectively, 40 vs. 23 years (odds ratio 1.056, 95% CI 1.05-1.07). Among the elderly HS cohort (in the Discussion, the HS tarda cohort) a female : male ratio of 1.7 : 1.0 and a higher family history for HS were found. Moreover, elderly patients with HS had a significantly higher risk of having HS-associated comorbidities compared with the sex- and age-matched controls. CONCLUSIONS: The prevalence of HS in the elderly is not rare. Among the elderly a shift from female predominance towards a lower female : male ratio in HS is observed. In addition, HS in the elderly showed significant variation in age of onset and involved body areas. Moreover, elderly patients with HS were more susceptible to multimorbidity. Finally, we propose defining HS in the elderly as 'HS tarda' and subdividing it as late-onset and persistent HS tarda.

Guselkumab for hidradenitis suppurativa: a phase II, open-label, mode-of-action study.

BACKGROUND: The effectiveness of available biologics for the treatment of hidradenitis suppurativa (HS) is limited. Additional therapeutic options are needed. OBJECTIVES: To investigate the efficacy and mode of action of guselkumab [an anti-interleukin (IL)-23p19 monoclonal antibody] 200 mg subcutaneously every 4 weeks for 16 weeks in patients with HS. METHODS: An open-label, multicentre, phase IIa trial in patients with moderate-to-severe HS was carried out (NCT04061395). The pharmacodynamic response in skin and blood was measured after 16 weeks of treatment. Clinical efficacy was assessed using the Hidradenitis Suppurativa Clinical Response (HiSCR), the International Hidradenitis Suppurativa Severity Score System (IHS4), and the abscess and inflammatory nodule (AN) count. The protocol was reviewed and approved by the local institutional review board (METC 2018/694), and the study was conducted in accordance with good clinical practice guidelines and applicable regulatory requirements. RESULTS: Thirteen of 20 patients (65%) achieved HiSCR with a statistically significant decrease in median IHS4 score (from 8.5 to 5.0; P = 0.002) and median AN count (from 6.5 to 4.0; P = 0.002). The overall patient-reported outcomes did not show a similar trend. One serious adverse event, likely to be unrelated to guselkumab treatment, was observed. In lesional skin, transcriptomic analysis revealed the upregulation of various genes associated with inflammation, including immunoglobulins, S100, matrix metalloproteinases, keratin, B-cell and complement genes, which decreased in clinical responders after treatment. Immunohistochemistry revealed a marked decrease in inflammatory markers in clinical responders at week 16. CONCLUSIONS: Sixty-five per cent of patients with moderate-to-severe HS achieved HiSCR after 16 weeks of treatment with guselkumab. We could not demonstrate a consistent correlation between gene and protein expression and clinical responses. The main limitations of this study were the small sample size and absence of a placebo arm. The large placebo-controlled phase IIb NOVA trial for guselkumab in patients with HS reported a lower HiSCR response of 45.0-50.8% in the treatment group and 38.7% in the placebo group. Guselkumab seems only to be of benefit in a subgroup of patients with HS, indicating that the IL-23/T helper 17 axis is not central to the pathophysiology of HS.

Adalimumab in conjunction with surgery compared with adalimumab monotherapy for hidradenitis suppurativa: A Randomized Controlled Trial in a real-world setting.

BACKGROUND: Adalimumab, the only biologic registered for hidradenitis suppurativa, shows clinical response in up to 60% of patients, leaving many patients in need for other treatment options such as surgery. OBJECTIVE: To compare the clinical effectiveness of adalimumab combined with surgery vs adalimumab monotherapy in patients with moderate to severe hidradenitis suppurativa. METHODS: A pragmatic Randomized Controlled Trial was performed from August 2018 to July 2022. Primary outcome was the difference in mean International Hidradenitis Suppurativa Severity Score System reduction after 12 months of treatment with the difference in mean Dermatology Life Quality Index reduction as a key secondary outcome. RESULTS: Thirty-one patients were included per arm. The mean International Hidradenitis Suppurativa Severity Score System at baseline was 23.9 ± 10.7 in the surgery group and 20.9 ± 16.4, in the monotherapy group. After 12 months of treatment the surgery group had a significantly greater reduction in International Hidradenitis Suppurativa Severity Score System compared with the monotherapy group (-19.1 ± 11.3 vs -7.8 ± 11.8, P < .001). Moreover, the surgery group showed a greater reduction in Dermatology Life Quality Index after treatment compared with the monotherapy group (-8.2 ± 6.2 vs -4 ± 7.7, P = .02). LIMITATIONS: The study follow-up was too short to assess surgical recurrence rates. DISCUSSION: Combining adalimumab with surgery resulted in greater clinical effectiveness and improved quality of life after 12 months in patients with moderate to severe hidradenitis suppurativa.

Clindamycin-Benzoyl Peroxide Gel Compared with Clindamycin Lotion for Hidradenitis Suppurativa: A Randomized Controlled Assessor-Blinded Intra-Patient Pilot Study.

BACKGROUND: Antibiotic resistance is a major concern, especially in hidradenitis suppurativa (HS). However, antibiotics form a cornerstone in its treatment. Topical clindamycin is known to cause bacterial resistance but is still advised as monotherapy for the treatment of mild to moderate HS. METHODS: This is a randomized, controlled, assessor-blinded, intra-patient pilot trial to compare the clinical efficacy of clindamycin-benzoyl peroxide gel with clindamycin lotion in patients with mild to moderate HS. Two contralateral body sites were randomized for treatment in each patient. The primary outcome was the difference in the International Hidradenitis Suppurativa Severity Score (IHS4) between the two groups after 12 weeks. Secondary objectives were feasibility of the intra-patient design, efficacy within treatment groups, effect on HS pain, HS itch, patient satisfaction, antibiotic resistance, and the prolonged efficacy after 16 weeks. RESULTS: Ten patients were included, resulting in two groups of 10 treated body sites. No significant differences were found between the two groups for all measurements after 12 or 16 weeks, while both therapies led to an improvement in the IHS4, pain, and itch scores. A significant decrease was observed in the IHS4 for both the clindamycin lotion (-1.5; p < 0.05) and the clindamycin-benzoyl peroxide gel (-2; p < 0.01) after 16 weeks, and the pain scores were reduced from 7 to 2.5, p < 0.01 and 6.5 to 3, p = 0.03, respectively. Using the IHS4-55, we identified 50% of patients as responders in both groups after 12 weeks. The intra-patient design, however, unexpectedly appeared to hinder the inclusion of patients. CONCLUSION: Clindamycin-benzoyl peroxide gel showed favorable clinical efficacy results, similar to clindamycin lotion, suggesting that it could replace clindamycin lotion in the treatment of mild to moderate HS and to prevent antibiotic resistance. A larger controlled trial is needed to validate these results.

Validity and Reliability of Two Digital Wound Measurement Tools after Surgery in Patients with Hidradenitis Suppurativa.

BACKGROUND: After excision surgery in patients with hidradenitis suppurativa (HS), wounds are usually left open for secondary intention healing. To evaluate wound healing, reliable wound measurement is important. However, digital wound measurement tools for measuring the surface area are validated for small wounds located on flat or mildly convex body surfaces in studies, often powered inadequately. Up until now, a validated digital measurement tool to accurately measure wounds on all body surfaces, including the intertriginous areas, was not available. OBJECTIVES: The aim of this study was to validate two digital wound measurement tools for the measurement of the surface area of larger and concave wounds, using surgical wounds in patients with HS. METHODS: This prospective observational validation study included consecutive patients with HS undergoing excision surgery in the Department of Dermatology of the Erasmus University Medical Center, Rotterdam. Wound measurements using a ruler, the tracing method, the inSight® 3-dimensional (3D) device, and the ImitoWound app were performed by three investigators. The intraclass correlation coefficients (ICCs) for concurrent validity and the intra- and inter-rater reliability were analyzed. The standard error of measurement (SEm) and minimal detectable change were calculated, and Bland-Altman plots were constructed to determine the limits of agreement. RESULTS: Twenty patients with a total of 52 wounds were included. The wounds had a mean surface of 18.7 cm2. The inSight® 3D device showed an ICC of 0.987 for concurrent validity, 0.998 for intra-rater reliability, and 0.997 for inter-rater reliability. The ICCs from the ImitoWound application were 0.974, 0.978, and 0.964 for concurrent validity, intra-rater reliability, and inter-rater reliability, respectively. The SEms for intra- and inter-rater reliability were 0.95 cm2 and 1.11 cm2 for the inSight® 3D device and 3.33 cm2 and 3.51 cm2 for the ImitoWound app, respectively. CONCLUSION: Both the inSight® 3D device and the ImitoWound app demonstrated excellent concurrent validity and reliability for the surface measurements of concave wound, enabling these tools to be used reliably in clinical research and daily practice. Furthermore, it paves the way for broader application, such as telemonitoring of wound care at home.

External Validation of the IHS4-55 in a European Antibiotic-Treated Hidradenitis Suppurativa Cohort.

BACKGROUND: Previously, a new dichotomous outcome was developed, calculated as 55% reduction in the International Hidradenitis Suppurativa 4 (IHS4-55) score. It was validated in datasets of adalimumab and placebo-treated HS patients. External validation is an important aspect of clinical outcomes. OBJECTIVES: We aimed to externally validate the novel dichotomous IHS4-55 in a non-biologic treated dataset of HS patients. METHODS: Data from a previously published European-wide prospective clinical study of antibiotic treatment of HS patients were used to assess the association of IHS4-55 achievement with individual reduction in inflammatory nodules, abscesses, and draining tunnels. Moreover, the associations between IHS4-55 positivity and achievement of the minimal clinically important differences (MCIDs) for Dermatology Life Quality Index (DLQI), Numerical Rating Scale (NRS) Pain, and NRS Pruritus were analyzed. RESULTS: Data were obtained from 283 individual patients, of which 36.4% (103/283) were treated with clindamycin and rifampicin and 63.6% (180/283) with tetracyclines for 12 weeks. Achievers of the IHS4-55 demonstrated a significant reduction the counts of inflammatory nodules, abscesses, and draining tunnels (all p < 0.001). Additionally, IHS4-55 achievers had an odds ratio for achieving the MCID of DLQI, NRS Pain, and NRS Pruritus of 2.16 (95% CI 1.28-3.65, p < 0.01), 1.79 (95% CI 1.10-2.91, p < 0.05), and 1.95 (95% CI 1.18-3.22, p < 0.01), respectively. CONCLUSIONS: This study shows the external validity of the novel IHS4-55 by demonstrating a significant association between IHS4-55 achievement and a reduction in inflammatory lesion counts as well as achievement of MCIDs for DLQI, NRS Pain, and NRS Pruritus in an antibiotic-treated cohort. These findings support the use of the IHS4-55 as a novel primary outcome measure in clinical trials.

Development and validation of IHS4-55, an IHS4 dichotomous outcome to assess treatment effect for hidradenitis suppurativa.

BACKGROUND: Validated, inclusive and easy-to-use outcomes for hidradenitis suppurativa are essential both in the clinical trial setting and clinical practice. The continuous IHS4 is a validated tool that dynamically assesses nodules/abscesses/draining tunnels and classifies disease severity as mild/moderate/severe. However, dichotomous outcomes are often required for clinical trials reporting. OBJECTIVE: To develop and validate a dichotomous outcome based on IHS4 that can be used in clinical trial settings and day-to-day clinical practice. METHODS: De-identified data from the PIONEER-I and -II studies were accessed through Vivli. Potential IHS4 thresholds were analysed using baseline to Week 12 data from adalimumab- and placebo-treated hidradenitis suppurativa patients in the PIONEER-I trial. The final threshold was chosen based on its ability to discriminate between patients treated with adalimumab or placebo and its association with reduction in inflammatory lesions. The final threshold was validated using data from baseline to Week 12 from adalimumab- and placebo-treated hidradenitis suppurativa patients in both the PIONEER-II and the combined PIONEER-I and -II studies. RESULTS: The best performing cut-off for the IHS4 was a 55% reduction of the IHS4 score (IHS4-55). Patients who achieved the IHS4-55 had an odd's ratio of 2.00 [95%-CI 1.26-3.18, p = 0.003], 2.79 (95%-CI 1.76-4.43, p < 0.001) and 2.16 (95%-CI 1.43-3.29, p < 0.001) for being treated with adalimumab rather than placebo in PIONEER-I, PIONEER-II and the combined dataset, respectively. Additionally, the achievement of the IHS4-55 was associated with a significant reduction in inflammatory nodules, abscesses and draining tunnels in all analysed datasets. CONCLUSIONS: IHS4-55, a novel dichotomous IHS4 version, based on a 55% reduction of the total score was developed. The IHS4-55 performs similarly to the HiSCR in discriminating between adalimumab- and placebo-treated hidradenitis suppurativa patients and shows significant associations with reductions in lesion counts. Moreover, the IHS4-55 addresses some of the HiSCR drawbacks by dynamically including draining tunnels in a validated manner. By allowing the analysis of hidradenitis suppurativa patients with an abscess and nodule count below 3 but many draining tunnels, this outcome measure will improve inclusivity in clinical trials.

Factors associated with treatment satisfaction in patients with hidradenitis suppurativa: results from the Global VOICE project.

BACKGROUND: Nearly half of patients with hidradenitis suppurativa (HS) report dissatisfaction with their treatment. However, factors related to treatment satisfaction have not been explored. OBJECTIVES: To measure associations between treatment satisfaction and clinical and treatment-related characteristics among patients with HS. METHODS: Treatment satisfaction was evaluated utilizing data from a cross-sectional global survey of patients with HS recruited from 27 institutions, mainly HS referral centres, in 14 different countries from October 2017 to July 2018. The primary outcome was patients' self-reported overall satisfaction with their current treatments for HS, rated on a five-point scale from 'very dissatisfied' to 'very satisfied'. RESULTS: The final analysis cohort comprised 1418 patients with HS, most of whom were European (55%, 780 of 1418) or North American (38%, 542 of 1418), and female (85%, 1210 of 1418). Overall, 45% (640 of 1418) of participants were either dissatisfied or very dissatisfied with their current medical treatment. In adjusted analysis, patients primarily treated by a dermatologist for HS had 1·99 [95% confidence interval (CI) 1·62-2·44, P < 0·001] times the odds of being satisfied with current treatment than participants not primarily treated by a dermatologist. Treatment with biologics was associated with higher satisfaction [odds ratio (OR) 2·36, 95% CI 1·74-3·19, P < 0·001] relative to treatment with nonbiologic systemic medications. Factors associated with lower treatment satisfaction included smoking (OR 0·78, 95% CI 0·62-0·99; active vs. never), depression (OR 0·69, 95% CI 0·54-0·87), increasing number of comorbidities (OR 0·88 per comorbidity, 95% CI 0·81-0·96) and increasing flare frequency. CONCLUSIONS: There are several factors that appear to positively influence satisfaction with treatment among patients with HS, including treatment by a dermatologist and treatment with a biologic medication. Factors that appear to lower treatment satisfaction include active smoking, depression, accumulation of comorbid conditions and increasing flare frequency. Awareness of these factors may support partnered decision making with the goal of improving treatment outcomes. What is already known about this topic? Nearly half of patients with hidradenitis suppurativa report dissatisfaction with their treatments. What does this study add? Satisfaction with treatment is increased by receiving care from a dermatologist and treatment with biologics. Satisfaction with treatment is decreased by tobacco smoking, accumulation of comorbid conditions including depression, and higher flare frequency. What are the clinical implications of this work? Awareness of the identified factors associated with poor treatment satisfaction may support partnered decision making and improve treatment outcomes.

The efficacy and tolerability of tetracyclines and clindamycin plus rifampicin for the treatment of hidradenitis suppurativa: Results of a prospective European cohort study.

BACKGROUND: Tetracyclines and clindamycin plus rifampicin combination therapy are both considered first-line therapy in current hidradenitis suppurativa guidelines. However, evidence for their efficacy is drawn from small studies, often without validated outcomes. OBJECTIVE: To assess the 12-week efficacy of oral tetracyclines and a combination of clindamycin and rifampicin. METHODS: A prospective, international cohort study performed between October 2018 and August 2019. RESULTS: In total, 63.6% of the included 283 patients received oral tetracyclines, and 36.4% were treated with clindamycin and rifampicin. Both groups showed a significant decrease in International Hidradenitis Suppurativa Severity Score System from baseline (both P < .001). The Hidradenitis Suppurativa Clinical Response (HiSCR) was achieved in 40.1% and 48.2% of patients, respectively (P = .26). Patient characteristics or disease severity were not associated with the attainment of HiSCR or the minimal clinically important differences for the Dermatology Life Quality Index and pain. LIMITATIONS: Cohort study. Respectively, 23.9% and 19.4% of patients had to be excluded from the HiSCR analysis for the tetracycline and combination therapy group because of a low abscess and nodule count at baseline. CONCLUSION: This study shows significant efficacy of both tetracycline treatment and clindamycin and rifampicin combination therapy after 12 weeks in patients with hidradenitis suppurativa. No significant differences in efficacy were observed between the 2 treatments, regardless of disease severity.

What causes hidradenitis suppurativa ?-15 years after.

The 14 authors of the first review article on hidradenitis suppurativa (HS) pathogenesis published 2008 in EXPERIMENTAL DERMATOLOGY cumulating from the 1st International Hidradenitis Suppurativa Research Symposium held March 30-April 2, 2006 in Dessau, Germany with 33 participants were prophetic when they wrote "Hopefully, this heralds a welcome new tradition: to get to the molecular heart of HS pathogenesis, which can only be achieved by a renaissance of solid basic HS research, as the key to developing more effective HS therapy." (Kurzen et al. What causes hidradenitis suppurativa? Exp Dermatol 2008;17:455). Fifteen years later, there is no doubt that the desired renaissance of solid basic HS research is progressing with rapid steps and that HS has developed deep roots among inflammatory diseases in Dermatology and beyond, recognized as "the only inflammatory skin disease than can be healed". This anniversary article of 43 research-performing authors from all around the globe in the official journal of the European Hidradenitis Suppurativa Foundation e.V. (EHSF e.V.) and the Hidradenitis Suppurativa Foundation, Inc (HSF USA) summarizes the evidence of the intense HS clinical and experimental research during the last 15 years in all aspects of the disease and provides information of the developments to come in the near future.

Apremilast for moderate hidradenitis suppurativa: Results of a randomized controlled trial.

BACKGROUND: Effective anti-inflammatory treatments for hidradenitis suppurativa (HS) are limited. OBJECTIVE: To evaluate the efficacy and short-term safety of apremilast in patients with moderate HS. METHODS: A total of 20 patients with moderate HS were randomized in a 3:1 ratio to receive blinded treatment with apremilast, 30 mg twice daily, or placebo for 16 weeks. The primary outcome was the Hidradenitis Suppurativa Clinical Response at week 16. Linear mixed effects modeling (analysis of covariance) was used to assess secondary clinical outcomes between treatment groups. RESULTS: The HS clinical response was met in 8 of 15 patients in the apremilast group (53.3%) and none of 5 patients in the placebo group (0%) (P = .055) at week 16. Moreover, the apremilast-treated patients showed a significantly lower abscess and nodule count (mean difference, -2.6; 95% confidence interval, -6.0 to -0.9; P = .011), NRS for pain (mean difference, -2.7; 95% -4.5 to -0.9; P = .009), and itch (mean difference, -2.8; 95% confidence interval, -5.0 to -0.6; P = .015) over 16 weeks compared with the placebo-treated patients. There was no significant difference in the Dermatology Life Quality Index over time between the 2 treatment groups (mean difference, -3.4; 95% confidence interval, -9.0 to 2.3; P = .230). The most frequently reported adverse events in the apremilast-treated patients were mild-to-moderate headache and gastrointestinal symptoms, which did not result in dropouts. LIMITATIONS: Small number of patients, relatively short study duration. CONCLUSION: Apremilast, at a dose of 30 mg twice daily, demonstrated clinically meaningful efficacy and was generally well tolerated in patients with moderate HS.

High prevalence of hidradenitis suppurativa in patients with perianal fistula.

BACKGROUND: Perianal fistula is an abnormal communication between the anal canal and perianal skin. Hidradenitis suppurativa (HS) is a chronic, auto-inflammatory skin disease in the intertriginous body areas, presenting with recurring abscesses, inflammatory nodules, and sinus tracts. The aim of this study was to determine the prevalence of HS in patients with a perianal fistula. METHODS: All patients with perianal fistula visiting a specialized proctology clinic between July and September 2017 were included and asked a validated diagnostic question for HS. Subsequently, physical examination was performed to objectively assess the diagnosis and relevant patient characteristics. RESULTS: In 6.6% (8/122) of patients, HS was diagnosed outside the perianal region. Four of these patients were newly diagnosed. The fistulas in HS patients were classified as a superficial fistula (three), a blind ending fistula (two), and a transsphincteric fistula (two). One patient had more than one type of fistula. CONCLUSION: The prevalence of HS in patients with a perianal fistula is at least 6.6%. This is higher than the prevalence reported in the general European population (1%) suggesting an association between perianal fistulas and HS. We stress the importance to screen for HS in patients with perianal fistulas in order to start appropriate anti-inflammatory treatment to reduce symptoms and disease progression.

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.

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.