Psoriasis as a comorbidity of hidradenitis suppurativa

S2k‐Leitlinie zur Therapie der Hidradenitis suppurativa/Acne inversa – Kurzfassung

Die S2k‐Leitlinie der Hidradenitis suppurativa/Acne inversa (HS/AI) soll eine akzeptierte Entscheidungshilfe für die Auswahl/Durchführung einer geeigneten/suffizienten Therapie liefern. Hidradenitis suppurativa/Acne inversa ist eine chronisch‐rezidivierende, entzündliche, potenziell mutilierende Hauterkrankung des terminalen Haartalgdrüsenapparats, mit schmerzhaften, entzündlichen Läsionen in den apokrinen drüsenreichen Körperregionen. Ihre Punktprävalenz in Deutschland ist 0,3%, sie wird mit einer Verspätung von 10,0 ± 9,6 Jahren diagnostiziert. Abnormale Differenzierung der Keratinozyten des Haartalgdrüsenapparats und eine begleitende Entzündung bilden die zentrale pathogenetische Grundlage. Primäre HS/AI‐Läsionen sind entzündliche Knoten, Abszesse und drainierende Tunnel. Rezidive in den letzten 6 Monaten mit mindestens zwei Läsionen an den Prädilektionsstellen verweisen auf eine HS/AI mit einer 97‐prozentigen Genauigkeit. HS/AI‐Patienten leiden an einer deutlichen Einschränkung der Lebensqualität. Zur korrekten Therapieentscheidung sollen Klassifikation und Aktivitätsbewertung mit einem validierten Instrument erfolgen, wie dem International Hidradenitis Suppurativa Severity Scoring System (IHS4). Hidradenitis suppurativa/Acne inversa wird nach der Ausprägung der nachweisbaren Entzündung in zwei Formen eingeteilt: aktive, entzündliche (milde, mittelschwere und schwere nach IHS4) und vorwiegend inaktive, nicht entzündliche (Hurley‐Grad‐I, ‐II und ‐III) HS/AI. Orale Tetrazykline oder eine 5‐tägige intravenöse Therapie mit Clindamycin sind mit der Effektivität von Clindamycin/Rifampicin vergleichbar. Subkutan applizierbares Adalimumab, Secukinumab und Bimekizumab sind für die Therapie der HS/AI zugelassen. Für die vorwiegend nicht entzündliche Erkrankungsform stehen verschiedene operative Verfahren zur Verfügung. Medikamentöse/chirurgische Kombinationen gelten als ganzheitliches Therapieverfahren.

S2k guideline for the treatment of hidradenitis suppurativa / acne inversa - Short version

The S2k guideline on hidradenitis suppurativa/acne inversa (HS/AI) aims to provide an accepted decision aid for the selection/implementation of appropriate/sufficient therapy. HS/AI is a chronic recurrent, inflammatory, potentially mutilating skin disease of the terminal hair follicle-glandular apparatus, with painful, inflammatory lesions in the apocrine gland-rich regions of the body. Its point prevalence in Germany is 0.3%, it is diagnosed with a delay of 10.0 ± 9.6 years. Abnormal differentiation of the keratinocytes of the hair follicle-gland apparatus and accompanying inflammation form the central pathogenetic basis. Primary HS/AI lesions are inflammatory nodules, abscesses and draining tunnels. Recurrences in the last 6 months with at least 2 lesions at the predilection sites point to HS/AI with a 97% accuracy. HS/AI patients suffer from a significant reduction in quality of life. For correct treatment decisions, classification and activity assessment should be done with a validated tool, such as the International Hidradenitis Suppurativa Severity Scoring System (IHS4). HS/AI is classified into two forms according to the degree of detectable inflammation: active, inflammatory (mild, moderate, and severe according to IHS4) and predominantly inactive, non-inflammatory (Hurley grade I, II and III) HS/AI. Oral tetracyclines or 5-day intravenous therapy with clindamycin are equal to the effectiveness of clindamycin/rifampicin. Subcutaneously administered adalimumab, secukinumab and bimekizumab are approved for the therapy of HS/AI. Various surgical procedures are available for the predominantly non-inflammatory disease form. Drug/surgical combinations are considered a holistic therapy method.

Increased cancer incidence among patients with hidradenitis suppurativa - a Danish nationwide register study 1977-2017

BACKGROUND

The chronic, inflammatory skin disease hidradenitis suppurativa (HS) (prevalence: 0.5%-1%, diagnostic delay: 7-10 years) primarily arises in younger adults and frequently coincides with autoimmune comorbidities and unhealthy life-styles (smoking and obesity). These factors are known to increase cancer risk, but despite this, information on cancer occurrence among HS patients is scarce.

MATERIALS AND METHODS

A nationwide retrospective register-based study assessing relative risk of cancer - overall and by anatomical site - following HS diagnosis expressed as standardized incidence ratios (SIRs), which is ratios between observed cases among all Danes diagnosed with HS since 1977 and expected cases based on cancer incidence rates of the entire Danish population during the same period.

RESULTS

Participants consisted of a cohort of 13,919 Danes with HS, who during an average of 14.2 years of follow-up developed a total of 1,193 incident cancers, corresponding to a 40% increased risk (SIR = 1.4, 95% CI: 1.3 to 1.4, p < 0.001). Increased risks were observed for cancers of the respiratory system, oral cavity and pharynx, digestive organs and peritoneum, urinary tract, and the lymphatic tissues.

INTERPRETATION

These findings underline an unmet need for health monitoring, lifestyle interventions and cancer screening if and when relevant.

Belgian Patients of the European Registry for Hidradenitis Suppurativa (ERHS-Be): Data, Scores, and Phenotypes since 2015

INTRODUCTION

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease, characterized by painful and recurrent lesions in apocrine gland-bearing skin areas. It is a heterogeneous disease, which makes assessment and data collection difficult. Questionnaires with detailed items, such as the Belgian European Registry for Hidradenitis Suppurativa (ERHS-Be), are useful to study HS and its associated comorbidities. The aim of this registry was to uncover new factors associated with HS and understand HS patients' clinical profiles and efficacy of treatments.

MATERIAL AND METHODS

The ERHS-Be registry is based on questionnaires, with sections for sociodemographic data, medical and HS history, clinical examination, and treatment plan. It allows identification of different clinical phenotypes and automatic calculation of severity scores.

RESULTS

At present, 606 patients are included in the ERHS-Be (67% women, 33% men). The mean age at the first visit is 38.5 years. Tobacco use is present in 72.6% of patients. A family history of HS is noted in 42% of patients. Comorbidities are documented in this cohort: depression is present in 43.8% of patients, arthritis in 27.8%, obesity in 31.5%, hypertension in 10.6%, diabetes mellitus in 6.4%, and dyslipidemia in 12.4%. Moreover, 7.7% of patients suffer from IBD and 27.4% have a pilonidal sinus. History of severe acne is found in 32.1% of patients and psoriasis in 9.3%. Thirteen percent of women in our cohort suffer from polycystic ovarian syndrome. Severity of disease is quantified in 533 patients: for instance, Hurley I, II, and III scores proportions are, respectively, 32.3%, 52.7%, and 15%, while the mean IHS4 score is 5.2. This registry also enables determination of relative phenotype proportions in our cohort, according to different classifications.

CONCLUSION

The ERHS-Be questionnaires allow systematic and larger data collection, including detailed comorbidities, phenotypes, and severity of disease. Analysis of this large database will contribute to a better understanding and management of HS, at a time where new therapeutic options are becoming available.

Epidemiology of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent skin disease affecting hair follicles in predominantly intertriginous areas, characterized by deep, painful nodules and abscesses, fistulas, sinus tracts, and scarring. The estimated global prevalence of HS is highly variable, as revealed in a growing body of published literature, and ranges from 0.053% to 4.1%. In North American and European patients, HS is three times more common in women than men, whereas in South Korea and Japan, male predominance is found. The disease most frequently manifests itself between the ages of 18 and 29. Numerous published studies have reported the association between smoking, obesity, and HS, although there are limitations in confirming the causal relationship due to the retrospective design of the available studies. Case-control studies have frequently evaluated the association between HS, metabolic syndrome, and other systemic comorbidities. Due to increased mental health problems, a higher risk of suicide in patients with HS has been reported. We provide up-to-date evidence about the epidemiology, genetic and environmental risk factors, comorbidities, and quality of life of patients with HS. The divergence in HS frequency, possibly due to differences in populations and methodologies, remains to be explained in future worldwide studies.

The Prevalent Comorbidome at the Onset of Psoriasis Diagnosis

INTRODUCTION

Psoriasis (PsO) is currently regarded as a systemic inflammatory disease with a growing burden of post-diagnosis associated comorbidities. To determine the initial burden of comorbiditis we evaluated the comorbidome at PsO onset.

METHODS

In a matched case-control study, we extracted data on 57,228 patients and 125 morbidities from the Clalit Health Services Israeli insurance database. PsO cases were matched with control individuals by sex and age at enrolment. As pre-existing comorbidities, we considered all conditions already present in controls at the same age as the matched PsO case at the time of their diagnosis. To test for differences in the odds of comorbidities between the case and control groups, logistic regression analyses were run to calculate the odds ratio (OR) for each comorbidity, after which the comorbidome was graphically represented.

RESULTS

In this study we enrolled 28,614 PsO patients and 28,614 controls with an average age of 45.3 ± 19.6 years. At the time of diagnosis, PsO patients were more likely to be diagnosed with 2-4 comorbidities (28.8% vs 23.8%) and > 5 (19.6% vs 12.9%,). PsO patients' specific comorbidomes evidenced several pathological cores: autoimmune and inflammatory systemic diseases [i.e., hidradenitis suppurativa (OR 3.55, 95% CI 1.88-7.28) or polymyalgia rheumatica (OR 3.01 95% CI 1.96-4.77)], inflammatory bowel diseases [i.e., Crohn's disease (OR 2.99 95% CI 2.20-4.13)], pulmonary inflammatory diseases [i.e., chronic obstructive pulmonary disease (OR 1.81 95% CI 1.61-2.04)], hepatological diseases [i.e., cirrhosis (OR 2.00 95% CI 1.36-3.00)], endocrine diseases [dysthyroidisms (OR 1.82 95% CI 1.30-2.59)], mental disorders [i.e., depression (OR 1.72 95% CI 1.57-1.87)], and cardiovascular diseases (i.e., hypertension (OR 1.47 95% CI 1.41-1.53)].

CONCLUSION

The PsO-onset comorbidome may help health professionals plan more comprehensive patient management. By screening for these common PsO-linked conditions, early diagnosis and treatment may become more frequent, thus greatly benefiting patients on their medical journey.

A Case of Psoriatic Disease and Hidradenitis Suppurativa in a Child with Chromosome 17q21.31 Microduplication Syndrome

Psoriatic disease is a chronic, relapsing inflammatory disorder, characterized mostly by cutaneous erythematous scaly plaques sometimes associated with arthritis. Hidradenitis suppurativa (HS) is a chronic relapsing inflammatory disease of the apocrine glands, characterized clinically by painful abscesses, sinus tracts and scars. It typically occurs after puberty, affecting mainly intertriginous areas of the body. There is a strong association between HS and psoriasis since they share the same pathogenic inflammatory pathway. The patient presented: low birthweight, microcephaly, facial dysmorphisms, lumbar hyperlordosis, walking difficulties, global psychomotor developmental delay and learning disabilities. A genetic evaluation revealed a 2.5 Mb de novo microduplication in the 17q21.31 chromosomal region. Dermatological examination revealed HS (Hurley stage II-HS) distributed in the genital area and inguinal folds, psoriatic plaques on the retroauricolar folds, on the elbows bilaterally and on the lateral aspect of the right ankle and psoriatic arthritis. The patient was treated with adalimumab, with a marked improvement of both conditions. To our best knowledge, we report the first case of coexisting Psoriatic Arthritis Disease and Hidradenitis Suppurativa in a child with chromosome 17q21.31 microduplication syndrome. We hypothesize that gene CRHR1 duplication included in the 17q21.31 chromosomal region might be involved in the pathogenesis of both diseases.

Sex-biased immunological processes drive hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin condition that can manifest with abscesses, sinus tracts, and scarring in the intertriginous areas of the body. HS is characterized by immune dysregulation, featuring elevated levels of myeloid cells, T helper (Th) cells, and pro-inflammatory cytokines, particularly those involved in Th1- and Th17-mediated immunity. In most epidemiological studies, HS shows a strong female sex bias, with reported female-to-male ratios estimated at roughly 3:1, suggesting that sex-related factors contribute to HS pathophysiology. In this article, we review the role of intrinsic and extrinsic factors that contribute to immunological differences between the sexes and postulate their role in the female sex bias observed in HS. We discuss the effects of hormones, X chromosome dosage, genetics, the microbiome, and smoking on sex-related differences in immunity to postulate potential immunological mechanisms in HS pathophysiology. Future studies are required to better characterize sex-biased factors that contribute to HS disease presentations.

Incidence, Risk Factors, and Prognosis of Hidradenitis Suppurativa Across the Globe: Insights from the Literature

Hidradenitis suppurativa, a chronic inflammatory disease of the skin, affects a patient's quality of life to a greater extent. While the disease burden, including its incidence and prevalence, has been extensively studied in the western population, there is a paucity of data from developing countries on the epidemiology of Hidradenitis suppurativa. Therefore, a general literature review was conducted to shed light on the epidemiology of Hidradenitis suppurativa across the globe. We reviewed the most recently available information on epidemiology, including incidence, prevalence, risk factors, prognosis and quality of life, complications, and associated comorbid among patients with Hidradenitis suppurativa. The estimated global prevalence of Hidradenitis suppurativa is found to be 0.00033-4.1%, with a relatively higher prevalence of 0.7-1.2% in European and US populations. Both genetic and environmental factors are associated with Hidradenitis suppurativa. Patients with Hidradenitis suppurativa have associated comorbid such as cardiovascular disease, type II diabetes mellitus, mental health issues, and sleep and sexual dysfunctions. These patients spend poor quality of life and tend to be less productive. Future studies are needed to assess the burden of Hidradenitis suppurativa in developing countries. Since the disease tends to be underdiagnosed, future studies should rely on clinical diagnosis rather than self-reporting to avoid the potential of recall bias. Attention needs to be diverted to developing countries with less amount of data on Hidradenitis suppurativa.

Risk of psoriasis in people with hidradenitis suppurativa: A systematic review and meta-analysis

Background

Hidradenitis suppurativa were associated with comorbidities in various organ systems. Inflammatory dermatological diseases such as pyoderma gangrenosum were reported to be associated with hidradenitis suppurativa. Nevertheless, as for the association between hidradenitis suppurativa and psoriasis, evidences were insufficient. In many studies, the association between psoriasis and hidradenitis suppurativa has been reported. However, some evidence seems to be controversial. The purpose of the systematic review and meta-analysis was to assess whether there was significant association between HS and psoriasis.

Methods

On June 01, 2022, we appraised 2,795 articles from databases including PubMed, Web of Science and Embase. Search syntaxes were based on 'hidradenitis suppurativa' or 'acne inversa' with "psoriasis", "comorbidities" or 'epidemiology'. Synonyms were determined based on MeSH terms and Emtree. Observational results that evaluated the odds ratio for people with hidradenitis suppurativa who had psoriasis were extracted for qualitative synthesis.

Results

After the selection process of the initial 2,795 studies, ten observational studies, including 3 cohort studies, 1 case-control study, and 6 cross-sectional studies, were extracted for critical appraisal. Based on the integration of 7 studies (with more than 560,000 participants included), people with hidradenitis suppurativa had a higher risk of having psoriasis, with a 2.67-fold risk (95% CI, 1.84, 3.87). The association remained in the sensitivity analyses utilizing strict adjustment models. In the analysis that only included studies with a similar study design and adjustments in obesity-related factors, the risk of people with hidradenitis suppurativa having psoriasis was 3.24 (95% CI, 2.27, 4.62). In male patients with HS, the risk of having psoriasis was 4.30-fold higher than male patients without HS (95% CI, 2.37, 7.78). Likewise, in an analysis including 3 cross-sectional studies, the risk of female HS patients having psoriasis was 3.94-fold higher than female HS-free patients (95% CI, 2.34, 6.63).

Conclusions

The co-occurrence of hidradenitis suppurativa and psoriasis can greatly increase the burden of the disease. Psoriasis could be one of the critical comorbidities of hidradenitis suppurativa and should be recommended for future screening and follow up. The association between the two diseases should be kept in mind in managing hidradenitis suppurativa patients. More prospective studies are needed to establish the true magnitude of the association between psoriasis and hidradenitis suppurativa.

Which hidradenitis suppurativa comorbidities should I take into account?

Hidradenitis suppurativa (HS) is a chronic, recurrent skin inflammatory disease associated with a variety of comorbidities, like metabolic syndrome, reduced quality of life, sexual dysfunction, working disability, inflammatory bowel disease, axial spondyloarthritis, depression and anxiety. Like psoriasis, HS patients have been found to have higher risk of cardiovascular death and suicide risk. Evidence suggests that for such a chronic, multi-comorbid disease, the use of validated outcomes to assess severity and effect of treatment, along with the use of clinically important patient reported outcomes, is essential. Clinicians should be informed about these comorbidities so that appropriate screening is implemented. The potential of available treatments to negatively and positively affect these comorbidities should also be taken into account when designing treatment strategies. This article aims to provide an outline of important HS comorbidities with emphasis on possible implications for daily clinical practice.

Insights into hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, debilitating, inflammatory skin disorder with a prevalence of around 1% and a profound impact on patients' quality of life. Characteristic lesions such as inflammatory nodules, abscesses, and sinus tracts develop in the axillae, inguinal, and gluteal areas, typically during or after puberty. A complex interplay of genetic predisposition, hormonal factors, obesity, and smoking contributes to development and maintenance of the disease. HS is considered to arise from an intrinsic defect within the hair follicle, leading to follicular plugging, cyst formation, and subsequent rupture that in turn induce an acute inflammatory response characterized by elevated levels of IL-1β, IL-17, and TNF. Over time, acute lesions transition into chronic disease, with active draining sinus tracts accompanied by extensive fibrosis. HS is associated with other immune-mediated inflammatory diseases, metabolic and cardiovascular disorders, and psychiatric comorbidities. Treatment of HS often requires a combination of antibiotic or immunosuppressing therapies and surgical intervention. Nonetheless, the currently available treatments are not universally effective, and many drugs, which are often repurposed from other inflammatory diseases, are under investigation. Studies into the early stages of HS may yield treatments to prevent disease progression; yet, they are hampered by a lack of appropriate in vitro and animal models.

Characterization of comorbidity heterogeneity among 13,667 patients with hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disorder characterized by recurrent abscesses in the groin and flexural areas. HS is associated with a wide range of comorbidities that complicate the disease course. Although these comorbidities have been well described, it remains unclear how these comorbidities coassociate and whether comorbidity profiles affect disease trajectory. In addition, it is unknown how comorbidity associations are modulated by race and sex. In this comprehensive analysis of 77 million patients in a large US population–based cohort, we examined coassociation patterns among HS comorbidities and identified clinically relevant phenotypic subtypes within HS. We demonstrated that these subtypes not only differed among races, but also influenced clinical outcomes as measured by HS-related emergency department visits and cellulitis. Taken together, our findings provide key insights that elucidate the unique disease trajectories experienced by patients with HS and equip clinicians with a framework for risk stratification and improved targeted care in HS.

Incidence, prevalence, and predictors of inflammatory arthritis in patients with hidradenitis suppurativa: a systematic review and meta-analysis

An increasing amount of evidence has emerged suggesting that hidradenitis suppurativa (HS) is associated with inflammatory arthritis. This study reviewed the incidence, prevalence, and predictors of inflammatory arthritis in patients with HS. A comprehensive literature search was conducted in CINAHL, Embase, and Medline from inception to February 14, 2020. Articles were included in the review if they provided data on disease epidemiology or predictors of adult or pediatric HS patients with comorbid inflammatory arthritis. There are no validated diagnostic criteria for HS, thus we considered patients as having HS if they had at least one diagnostic code in a hospital or claims database or a diagnosis of HS/inflammatory arthritis in a medical record. The same criteria were used to confirm presence of inflammatory arthritis. We identified an increased incidence of rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA) in HS patients when compared with estimates in the general population. We identified a relatively high prevalence of RA, spondyloarthritis (SpA), and PsA in HS patients when compared with estimates in the general population. There was evidence to suggest that patients who are younger than 30, male, have severe HS, or are taking infliximab or adalimumab (which may also be confounded by HS disease severity) may be at greater risk for specific subtypes of inflammatory arthritis. However, further data are needed to confirm these associations. The increased incidence and prevalence of inflammatory arthritis within HS patients underscore the need for increased awareness and interdisciplinary partnership within rheumatology and dermatology.

Target molecules for future hidradenitis suppurativa treatment

The registration of the tumour necrosis factor-α inhibitor adalimumab in 2015 was a major step forward in the treatment of hidradenitis suppurativa/acne inversa (HS). However, it soon became evident that the effectiveness of adalimumab in daily practice was highly variable. A significant unmet medical need of HS patients remained, and the search for novel therapeutic targets was intensified. During the 10th European Hidradenitis Suppurativa Foundation (EHSF) e.V. Conference, reknown international HS investigators virtually presented and discussed the published data on these potential target molecules for future HS treatment. This article addresses the most promising molecules currently under investigation from a pathophysiological and clinical point of view. With phase III trials ongoing, the anti- interleukin (IL)-17 biologics bimekizumab and secukinumab are in the most advanced stage of clinical development showing promising results. In addition, targeting IL-1α with bermekimab has shown encouraging results in two clinical trials. Directing treatment at neutrophil recruitment and activation by targeting IL-36 with spesolimab fits well in the pathogenic concept of HS and clinical phase II trial results are pending. In contrast to in situ evidence, Complement 5a (C5a) and C5a receptor blockade have only shown greater clinical benefit in patients with severe HS. Inhibition of Janus kinase (JAK) 1 signalling in HS showed clinical efficacy only in the highest dosage, highlighting that careful surveillance of the balance between safety and efficacy of JAK inhibition is warranted. Overall, clinical efficacies of all novel treatments reported so far are modest. To guide drug development, more and better-defined translational data on the pathogenesis of this severe and enigmatic inflammatory skin disease are required.

Coprevalence of Hidradenitis Suppurativa and Psoriasis: Detailed Demographic, Disease Severity and Comorbidity Pattern

BACKGROUND AND OBJECTIVES

Hidradenitis suppurativa (HS) and plaque psoriasis (Pso) are supposed to have a coprevalence. However, data showing a more detailed description of patients with both diseases are rare. In this study, we characterized patients with both skin diseases in terms of onset, disease course, severity, concomitant diseases and therapeutical management.

PATIENTS AND METHODS

Data from 28 patients with a confirmed codiagnosis of HS and Pso from 2 university hospitals presented between 2015 and 2019 were evaluated retrospectively. For further characterization, patients were divided into different cohorts depending on whether HS or Pso was diagnosed as the first disease.

RESULTS

The average age of patients with a coprevalence of both diseases was 44.4 years with a female/male ratio of 1:1.15. Fifteen patients were diagnosed first with HS at an average age of 22.8 years, 13 patients first showed symptoms of Pso at a mean age of 21.7 years. The average time to the onset of the corresponding second disease was 14.3 years. Patients with HS as first disease showed a significantly severer form of HS compared to patients with a first diagnosis of Pso (mean highest International Hidradenitis Suppurativa Severity Score System: 23.5 vs. 8.2; p = 0.02). Severity of psoriatic disease in patients with HS at first diagnosis was numerically lower but not significant compared to the cohort with Pso at first diagnosis (mean highest Psoriasis Area and Severity Index: 7.8 vs. 13.2; p = 0.299). The most frequent comorbidity in all patients was obesity (64.3%; mean body mass index: 32.2) followed by psychiatric complaints (25%) and psoriatic arthritis (21.4%). Adalimumab was the most commonly used drug that had a positive effect on both diseases, HS and Pso.

CONCLUSIONS

In patients with a coprevalence of HS and Pso, the disease which occurs first appears to take a severer course, with an increased risk of development of obesity and psychiatric comorbidity in both cohorts.

The epidemiology of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease defined clinically by multiple, painful inflammatory lesions occurring predominantly in flexural sites. Onset is typically soon after puberty; however, it remains unknown whether the menopause induces remission. In North American and European patients with HS the female-to-male ratio is approximately 3 : 1 but the ratio is 1 : 2 in South Korean patients. It may be that some elements of HS epidemiology cannot be generalized across all populations. Elements of HS epidemiology in the USA and Europe are well established, including strong associations with obesity and smoking, which may increase disease severity. There are associations between HS and other cardiovascular disease (CVD) risk factors, including type 2 diabetes and metabolic syndrome. People with HS have double the risk of death from CVD compared with those without HS and 1·5 times the risk compared with patients with psoriasis. Depression and anxiety are associated with HS and completed suicide rates in those with HS are more than double the rates in controls. Associations exist between HS and other chronic inflammatory conditions, particularly inflammatory bowel disease and inflammatory arthritis. Case-control studies demonstrate associations with pilonidal sinus, polycystic ovary syndrome, Down syndrome, obstructive sleep apnoea and pyoderma gangrenosum. Population-based studies using routinely collected healthcare data from the USA estimate a prevalence of 0·1%, suggesting HS is relatively uncommon. European studies include undiagnosed patients and typically estimate prevalence of 1% or more, suggesting a common condition. Resolving the controversy surrounding a greater than 10-fold difference in HS prevalence estimates remains a high priority.

Hidradenitis Suppurativa and Concurrent Psoriasis: Comparison of Epidemiology, Comorbidity Profiles, and Risk Factors

Introduction

Hidradenitis suppurativa (HS) is a chronic, debilitating, and inflammatory skin disease. The epidemiology of HS varies greatly, with an estimated prevalence ranging from 0.03% to 4% worldwide. Similar to psoriasis (PsO), HS also exhibits a systemic inflammatory nature with a spectrum of systemic comorbidities. A large health insurance claims (HICs) database is analyzed to determine the demography and epidemiology of HS, PsO, and HS with concurrent PsO (HS-PsO) patients. Furthermore, the comorbidity profiles, including the comorbidity risk of these patient populations, are analyzed.

Methods

This is a noninterventional retrospective analysis of anonymized HICs data using a subset of the Institute of Applied Health Research Berlin (InGef) database. The primary outcome is the prevalence and incidence of HS, PsO, and HS-PsO. Secondary outcomes include comorbidity profiles and a comorbidity risk analysis.

Results

The prevalence and incidence of HS were 0.0681% and 0.0101%, respectively. The prevalence of HS-PsO was 0.004% (6% of the total HS population). HS patients frequently suffered from arterial hypertension (45%), nicotine dependence (46%), obesity (41%), and depression (36%), which were more common in HS-PsO patients compared with HS alone. HS patients had an increased prevalence of metabolic, psychiatric, immune-mediated, and cardiovascular diseases, e.g., overweight/obesity [odds ratio (OR): 2.65, 95% confidence interval (CI) 2.37–2.96], depression (OR: 1.55, 95% CI 1.42–1.76), or seronegative rheumatoid arthritis (OR: 2.82, 95% CI 1.61–4.94) compared with the overall population. The increased risk of myocardial infarction in HS patients (OR: 4.1, 95% CI 3.5–4.8, adjusting for age/sex) was largely attributed to patient’s current smoking status (OR: 1.1, 95% CI 0.8–1.5, adjusting for smoking/age/sex).

Conclusions

HS patients show a broad spectrum of inflammatory and metabolic syndrome-related comorbidities, with an increased risk by concurrent PsO. Important for clinical practice, the elevated cardiovascular risk of HS patients can be largely attributed to smoking.

Electronic supplementary material

The online version of this article (10.1007/s13555-020-00401-y) contains supplementary material, which is available to authorized users.

Review of Comorbidities of Hidradenitis Suppurativa: Implications for Daily Clinical Practice

Hidradenitis suppurativa (HS) is a chronic, recurrent skin inflammatory disease associated with a variety of comorbidities, like reduced quality of life, metabolic syndrome, sexual dysfunction, working disability, axial spondyloarthritis, inflammatory bowel disease, depression, and anxiety. Like psoriasis, HS patients have been found to have higher risk of cardiovascular death and suicide risk. Clinicians should be informed about these comorbidities so that appropriate screening is implemented. All this evidence suggests that for such a chronic, multi-comorbid disease, the use of validated outcomes to assess severity and effect of treatment, along with the use of clinically important patient reported outcomes, is essential. The potential of available treatments to negatively and positively affect these comorbidities should also be taken into account when designing treatment strategies. This review provides an outline of important HS comorbidities with emphasis on possible implications for daily clinical practice.