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Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with severe consequences on quality of life. One aspect of this is that HS has been linked to an increased risk of infertility, but as data is still limited, it is not known if the association reflects causality. We performed a cross-sectional study of 161 female participants included at Zealand University Hospital, Roskilde, Denmark. Data regarding basic demographics, infertility, pregnancies, sexual function, and known factors with impact on fertility was collected. Logistic regressions were performed to analyze the association between HS and infertility, adjusting for factors that influence fertility. The study population consisted of 55 patients with HS, 55 patients with other dermatological diseases (ODD), and 51 healthy controls (HC). The HS group had a higher BMI, lower sexual function, and a higher tobacco use. We found no significant difference between the three groups in terms of whether they had children, the number of children they had, infertility, or whether they had received fertility treatments. The logistic analyses found no correlation between HS and infertility, and adjusting for factors affecting infertility did not alter this result. This study did not find a significant difference in infertility between patients with HS compared to those with ODD or HC. This result was not affected by adjustments for other factors known to influence fertility. Interestingly, the lower sexual function in the HS group did not appear to influence their desire or ability to conceive., (© 2024. The Author(s).)

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.

The typical Hidradenitis Suppurativa (HS) patient is a young woman with axillary and groin involvement, but the spectrum of the disease presentation is broad and no internationally acknowledged sub-classification of the disease exists to date. It is however speculated that different, yet unidentified, subtypes may respond differently to different treatments or carry a different prognosis. Classification according to self-reported clinically meaningful outcomes for patients offer practical advantages. Our objective was to build an empirical framework for sub-classification of HS patients based on the frequency of HS flares in various anatomic locations, using a cross-sectional questionnaire-based design. All patients with a clinically confirmed diagnosis of HS registered at our department until March 1, 2017 were invited to participate. The frequency of HS flares in various anatomic locations was used for identification of possible HS subtypes using Principal Component Analysis (PCA) and cluster analysis. A total of 524 (62%) of 845 invited patients answered the questionnaire; 402 (76.7%) were female. From the cluster analysis, we identified two possible subtypes of HS, labeled the "upper type" and the "lower type". The "upper type" was characterized by repeated outbreaks in axillary and mammary regions. Meanwhile, the "lower type" was characterized by outbreaks in the inguinal, genital, perianal, and gluteal regions. Our findings support the notion that HS can be sub-classified and imply that the pattern of where lesions are located may be an important element in future HS sub-classification systems., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Hidradenitis suppurativa (HS) is a recurrent inflammatory skin disease that, apart from rare causative loss-of-function mutations, has a widely unknown genetic aetiology., Objectives: To estimate the relative importance of genetic and environmental factors underlying susceptibility to HS., Methods: Via the Danish Twin Registry and the Danish National Patient Registry we pulled together information on zygosity with that of HS status. Cases of HS were identified by the International Classification of Diseases (ICD)-8 (705·91) and ICD-10 (L73·2). Heritability was assessed by the classic biometric model and the possibility of gene-gene interaction via the multilocus modelling approach., Results: Among 100 044 registered twins, we found 170 twins (from 163 pairs) diagnosed with HS. The seven concordant pairs were all monozygotic. Monozygotic twins had a case-wise concordance rate of 28% [95% confidence interval (CI) 7-49], corresponding to a familial risk of 73 (95% CI 13-133) times that of the background population. The biometrical modelling suggested a heritability of 0·80 (95% CI 0·67-0·93), and the multilocus index estimate was 230 (95% CI 60-400). This is highly indicative of gene-gene interactions, with the possibility of up to six interacting loci., Conclusions: This twin study was substantially larger and employed a more valid phenotype than previous studies. Genetics account for the majority of HS susceptibility, and HS is most likely caused by gene-gene interactions rather than monogenetic mutations or solely additive genetic factors. New approaches aimed at assessing potential interactions at a single-nucleotide polymorphism (SNP)-SNP level should be implemented in future HS genome-wide association studies., (© 2021 British Association of Dermatologists.)

Hidradenitis suppurativa is a common recurrent inflammatory skin disease. It is associated with multiple comorbidities whose temporal relationships are unknown due to long diagnostic delays. This study of otherwise healthy blood donors with self-reported symptoms of hidradenitis suppurativa investigated the temporal relationships of comorbidities. A prospective survival analysis on a nationwide cohort of blood donors, using registry data on drug prescription, was used to calculate the hazard ratio of time until first prescription of medical treatment for the following hidradenitis suppurativa-related comorbidities: heart disease, diabetes, depression, thyroid disease and pain. Hidradenitis suppurativa status was determined by a validated questionnaire, and the survival analysis was adjusted for age, sex, body mass index, smoking status and having an International Classification of Diseases Version 10 (ICD-10) diagnosis of hidradenitis suppurativa. Of the participants, 1,012 reported hidradenitis suppurativa symptoms, and these symptoms increased the hazard ratio of antidepressants (1.73, 95% confidence interval 1.17-2.56, p ≈ 0.006) and analgesics (hazard ratio 1.24, 95% confidence interval 1.11-1.39, p < 0.001). Pain and depression are the first comorbidities to present in hidradenitis suppurativa pathogenesis.

Hidradenitis suppurativa (HS) has a substantial impact on patients' lives. We identified factors associated with decreased quality of life (QoL) in patients with HS. Consecutive newly referred patients with HS attending a tertiary referral centre for HS were evaluated with the dermatology life quality index (DLQI). Clinical evaluation was performed according to the Hurley stage. Furthermore, disease duration, number of boils in the past month, boil-associated pain score, overall disease-related distress score, smoking status, employment status and comorbidities were recorded. A total of 339 patients with a mean age of 39.4 years were included; 218 (64.3%) females and 121 (35.7%) males. Of these, 96 (28.3%) had Hurley stage I, whereas 195 (57.5%) and 48 (14.2%) had Hurley II and III, respectively. The mean BMI was 29.0 (SD 7.1) kg/m 2 and 75.2% of patients were current or former smokers. The mean overall DLQI score was 11.9 (SD 7.6). After mutual adjustment for clinical characteristics a significant difference in mean overall DLQI score was observed between severity groups (8.6 vs. 12.6 vs. 16.1, adjusted p < 0.001, for Hurley I, II and III, respectively), age group (12.1 vs. 12.1 vs. 12.5 vs. 7.1, adjusted p = 0.002, for ≤ 20, 21-40, 41-60 and > 60 years, respectively), employment status (11.0 vs. 14.6, adjusted p = 0.003, for employed and unemployed, respectively), presence of boils in the preceding month (8.3 vs. 13.6, adjusted p = 0.001, for no boils and presence of boils, respectively), higher overall disease-related distress score (6.3 vs. 13.9, adjusted p < 0.001, for low and high score, respectively), involvement of the groins (8.7 vs. 13.0, adjusted p = 0.035 for no and involvement, respectively), high number of anatomical regions involved (9.8 vs. 12.4 vs. 14.5, adjusted p = 0.007 for 0-1, 2 and ≥ 3 anatomical regions involved, respectively) and diabetes (11.5 vs. 15.2, adjusted p = 0.043, for no and diabetes, respectively). All ten individual DLQI question scores increased significantly with increasing Hurley stage. Patients with HS referred for specialized hospital care report substantial impact on the quality of life. Disease severity (Hurley stage), younger age, diabetes, recent and increasing disease activity and specific anogenital localization are major aggravating factors.

Importance: Hidradenitis suppurativa (HS) is a chronic skin disease characterized by recurrent inflamed nodular lesions and is associated with multiple comorbidities; previous studies have been of cross-sectional design, and the temporal association of HS with multiple comorbidities remains undetermined., Objective: To evaluate and characterize disease trajectories in patients with HS using population-wide disease registry data., Design, Setting, and Participants: This retrospective registry-based cohort study included the entire Danish population alive between January 1, 1994, and April 10, 2018 (7 191 519 unique individuals). Among these, 14 488 Danish inhabitants were diagnosed with HS or fulfilled diagnostic criteria identified through surgical procedure codes., Exposures: Citizens of Denmark with a diagnosis code of HS as defined by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) or as identified through surgical procedures., Main Outcomes and Measures: Disease trajectories experienced more frequently by patients with HS than by the overall Danish population. Strength of associations between disease co-occurrences was evaluated using relative risk (RR). All significant disease pairs were tested for directionality using a binomial test, and pairs with directionality were merged into disease trajectories of 3 consecutive diseases. Numerous disease trajectories were combined into a disease progression network showing the most frequent disease paths over time for patients with HS., Results: A total of 11 929 individuals were identified by ICD-10 diagnosis codes (8392 [70.3%] female; mean [SD] age, 37.72 [13.01] years), and 2791 were identified by procedural codes (1686 [60.4%] female; mean [SD] age, 37.38 [15.83]). The set of most common temporal disease trajectories included 25 diagnoses and had a characteristic appearance in which genitourinary, respiratory, or mental and behavioral disorders preceded the diagnosis of HS and chronic obstructive pulmonary disease (604 cases [4.2%]; RR, 1.57; 95% CI, 1.55-1.59; P < .001), pneumonia (827 [5.7%]; RR, 1.18; 95% CI, 1.15-1.20; P < .001), and acute myocardial infarction (293 [2.0%]; RR, 1.37; 95% CI, 1.35-1.39; P < .001) developed after the diagnosis., Conclusions and Relevance: The findings suggest that patients with newly diagnosed HS may have a high frequency of manifest type 1 diabetes and subsequent high risk of acute myocardial infarction, pneumonia, and chronic obstructive pulmonary disease.

Importance: There is a lack of evidence on the association of birth weight, childhood body mass index (BMI), change in BMI during childhood, and childhood height with subsequent risks of hidradenitis suppurativa (HS) in adulthood., Objective: To investigate the association of birth weight, childhood BMI, change in BMI during childhood, and childhood height with subsequent risks of HS in adulthood in a large Danish population-based cohort., Design, Setting, and Participants: This cohort study included 347 200 schoolchildren from the Copenhagen School Health Records Register born from 1930 to 1996 who were linked to the Danish National Patient Register of hospital discharge diagnoses to identify cases of HS. Birth weight was reported by parents or guardians, whereas childhood weight and height were measured by school physicians or nurses at ages 7 through 13 years. Cox proportional hazards regressions were used to estimate hazard ratios (HRs) and 95% CIs. Statistical analysis was performed from February 20, 2019, to May 15, 2019., Main Outcomes and Measures: A diagnosis of HS as recorded in the Danish National Patient Register., Results: Among the 347 200 children included in the study (175 750 boys) during the follow-up period from 1977 to 2017, 1037 individuals (677 females; median age at diagnosis, 39 years [range, 15-73 years]) received a diagnosis of HS. A nonlinear (U-shaped) association was found between birth weight and HS, such that both the lightest (2.00-2.75 kg; HR, 1.36 [95% CI, 1.10-1.68]) and the heaviest babies (4.26-5.50 kg; HR, 1.39 [95% CI, 1.01-1.93]) had increased risks of HS compared with normal-weight babies (3.26-3.75 kg; P = .04 for deviation from linearity). The risk of HS increased significantly with increasing BMI z score at each age from 7 to 13 years, from an HR of 1.32 (95% CI, 1.24-1.40) per BMI z score at 7 years of age to an HR of 1.50 (95% CI, 1.40-1.61) per BMI z score at 13 years of age. Compared with children with a normal weight at 7 and 13 years of age, those with a normal weight at 7 years of age and overweight at 13 years of age had a significantly increased risk of HS (HR, 2.11 [95% CI, 1.63-2.74]) and children with persistent overweight at both ages also had an increased risk of HS (HR, 2.61 [95% CI, 2.02-3.38]). Children with overweight at 7 years of age but with normal weight at 13 years of age did not have a significantly increased risk of HS (HR, 1.05 [95% CI, 0.67-1.67]). Childhood height at all ages was not associated with risk of HS (children at 7 years had an HR of 1.00 [95% CI, 0.94-1.07], and those 13 years had an HR of 1.06 [95% CI, 0.99-1.13], per z score)., Conclusions and Relevance: This cohort study found that both the lightest and heaviest babies had increased risks of HS. Childhood BMI was positively and significantly associated with risk of HS development in adulthood. These findings suggest that returning to normal weight before puberty reduces risks of HS to levels observed in children who were never overweight. Childhood height was not associated with risk of HS.

Background: Hidradenitis suppurativa (HS) and psoriasis (PSO) appear to share important pathogenic elements; in spite of this, the co-occurrence of the two has been widely unexplored., Methods: To explore the co-occurrence of HS and PSO, we recorded the number of patients attending the outpatient clinic at the Department of Dermatology, Zealand University Hospital, Roskilde, Denmark, for the ICD10 diagnosis HS (DL73.2) or PSO (DL40.0, DL40.3, DL40.4, DL40.8, and DL40.9). Data were further compared with previously reported Danish national prevalence rates for HS and PSO., Results: A total of 1,036 patients were included from the outpatient clinic: 440 HS, 624 PSO, and 28 with both diagnoses. In total 6.4% of HS patients had PSO, and 4.5% of PSO patients had HS. HS patients had OR = 2.99 (95% CI 2.04-4.38) of having PSO as compared to the background population. For PSO patients, they had OR = 2.56 (95% CI 1.74-3.77)., Discussion: We found a strong association between HS and PSO, which implies a possible comorbidity between PSO and HS that has not previously been properly elucidated. Such a connection could be a common inflammatory pathway driven by the increased secretion of IL-12/23 and TNFα that is a hallmark of both diseases., (© 2019 The International Society of Dermatology.)

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease characterized by recurrent inflamed nodules. No pathognomonic test is available for HS; hence the diagnosis is based on three clinical criteria., Objectives: To estimate the cross-sectional prevalence and characterize patients with HS in the Danish Blood Donor Study cohort., Methods: A questionnaire previously developed containing HS screening questions, the Major Depression Inventory, the Short Form-12, as well as questions about height, weight and drinking habits was answered by 27 765 blood donors., Results: The prevalence of HS was 1·8% [95% confidence interval (CI) 1·6-2·0%] in the cohort of Danish blood donors. Donors with HS were on average 4·7 years younger (P < 0·001), had 1·3 kg m -2 higher mean body mass index (BMI) (P < 0·001) and were significantly more likely to smoke [odds ratio (OR) 1·44, 17·9% vs. 13·1%, P = 0·002] compared with donors without HS. Furthermore, significantly more donors with HS were classified as having moderate depression (3·2% vs. 0·7%, P < 0·001). Also, significantly more patients with HS were apprenticeship educated, received educational support and sickness or cash benefits., Conclusions: The prevalence of HS in the cohort of blood donors was estimated to 1·8% (95% CI 1·6-2·0%). Donors with HS reported characteristics similar to those reported for hospital-based patients with HS such as higher BMI, smoking rates and lower socioeconomic status than donors without HS., (© 2018 British Association of Dermatologists.)

Background: Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease, recently associated with metabolic syndrome, subclinical atherosclerosis and increased risk of cardiovascular disease., Objectives: To investigate the hitherto unknown electrocardiographic (ECG) changes associated with HS, which have recently been associated with significant cardiovascular burden., Methods: Data were obtained from the cross-sectional Danish General Population Study (GESUS). HS diagnosis was based on a validated self-reported questionnaire; 404 individuals met the HS diagnosis criteria and 19 001 controls without HS were identified. Severity of HS was staged according to a modified Hurley score. The ECG parameters of heart rate (HR), PR interval, QRS duration, JTc interval and QTc interval were obtained from 12-lead resting ECGs. We investigated the difference in means by unpaired t-test or anova., Results: HR was significantly higher [mean difference 2·3 beats per min (bpm), 95% confidence interval (CI) 1·2-3·4; P < 0·01] when adjusting for age and sex, but when adjusting for multivariates, there was no significant difference (0·3 bpm, 95% CI -0·7 to 1·4; P = 0·52). Severe HS was significantly associated with increased HR across all models (2·9 bpm, 95% CI 0·7-5·1; P = 0·01). Mean QRS duration was significantly shorter in the group with mild HS but not in the groups with moderate and severe HS., Conclusions: Mean resting HR in patients with severe HS was significantly higher compared with controls. Given that resting HR is associated with increased risk of all-cause and cardiovascular mortality, and that patients with HS have increased risk of cardiovascular events, this finding is potentially important, easily testable and intervenable., (© 2017 British Association of Dermatologists.)

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory dermatological disease that was recently linked to the metabolic syndrome (MetS). MetS has been associated with gallstones, and nonalcoholic fatty liver has been suggested to be the hepatic expression of MetS., Objective: The objective of the study was to investigate whether there was an association of HS with gallstones as well as with hepatic dysfunction., Patients and Methods: This was a cross-sectional study comparing a hospital-based HS group, a population-based HS group, and controls for self-reported gallstone and blood sample verified hepatic dysfunction. Blood samples were analyzed for alanine transaminase, bilirubin, alkaline phosphatase, albumin, thrombocytes, and the international normalized ratio., Results: A total of 32 hospital HS patients, 430 population-based HS patients, and 20 780 non-HS controls were identified. The age-sex-smoking-adjusted analysis of gallstones revealed a significant OR of 1.72 (95% CI 1.23-2.42, P=0.0191) and a borderline significant OR of 3.28 (95% CI 1.24-8.74, P=0.0516) for the population HS group and hospital HS group versus controls, respectively. Furthermore, no clinically significant evidence was found with regard to hepatic dysfunction., Conclusion: This study demonstrates an association of HS with gallstones, but not with hepatic dysfunction. The association with gallstones may be partly explained by the comorbidity of hypertriglyceridemia and obesity as a part of MetS.

Background: Chronic inflammatory diseases other than hidradenitis suppurativa (HS) have been associated with prothrombotic/hypercoagulable status., Objective: To investigate a possible association between the chronic inflammatory skin disease HS and prothrombotic/hypercoagulable state., Methods: We performed a hospital- and population-based cross-sectional study investigating the coagulation status (thrombocytes, mean platelet volume [MPV], international normalized ratio [INR] and activated partial thromboplastin time [APTT])., Results: 32 hospital HS subjects, 430 population HS subjects and 20,780 population non-HS control subjects were identified. The adjusted analyses showed no differences in the levels of thrombocytes, MPV, INR or APTT between the HS groups (hospital HS group, population HS group) when compared to controls (p = 0.089, p = 0.3078; p = 0.5499, p = 0.0659; p = 0.0932; p = 0.3432)., Conclusion: We did not find an association between HS and prothrombotic/hypercoagulable status. Thus, thrombocytes may not be activated in HS. Furthermore, INR may not be affected in HS, suggesting that intrinsic and vitamin K-dependent coagulation factors appear unaffected.

Background: Hidradenitis suppurativa (HS) causes considerable morbidity. The long-term prognosis is of obvious interest to both patients and physicians. We conducted this study to determine the prognosis and risk factors in patients diagnosed with HS., Objectives: To describe the long-term prognosis and the clinical course of HS and its association to known risk factors., Methods: A postal follow-up survey with uncomplicated factual questions was conducted. As all of the patients were well acquainted with their long-standing disease, this was thought to be sufficient for meaningful results. All cases were diagnosed by a dermatologist. Overall, 212 patients diagnosed with HS between 1981 and 2001 were studied after a median follow-up period of 22 years (range 12-32)., Results: The overall response rate was 71.2%, with 60.8% (129/212) valid (fully completed) questionnaires. Remission was reported by 39.4% (50/127) and improvement by 31.5% (40/127). Unchanged severity was reported by 20.5% (26/127), and 8.7% (11/127) experienced worsening disease. Tobacco smoking was reported by 92.2% (119/129). Among nonsmokers, 40% (35/88) reported remission vs. 29% (17/59) of active smokers. A higher proportion of nonobese patients (45%) reported remission than obese patients (23%)., Conclusions: We found that 39.4% of the sample reported remission of HS. Suspected risk factors appeared to influence the prognosis. Smoking and obesity were significantly linked to a lower rate of self-reported remission. The notion that lifestyle factors play a role in HS appears to be supported by this survey., (© 2014 British Association of Dermatologists.)

The prevalence of hidradenitis suppurativa (HS) has been estimated to be 1% of the population. Obesity is considered a co-morbidity, but the prevalence of HS in obese population is not known. A retrospective questionnaire was distributed to 383 patients over 2 years after bariatric surgery. Data on pre- and post-surgery HS symptoms and disease severity were studied. Disease severity was assessed by number of involved sites. General skin problems rated numerically on an anchored 1-10 scale. Valid responses were obtained from 249/383 (65%). A point prevalence of 18.1% (45/249) HS was found. The number of patients reporting HS symptoms after weight loss decreased by 35% and the mean number of involved sites was reduced from 1.93 to 1.22 following weight loss (p = 0.003). The prevalence of HS appears higher in the obese than in the background population, and a weight loss of more than 15% is associated with a significant reduction of disease severity.

Background: Hidradenitis suppurativa (HS) is a chronic inflammatory disease involving inverse recurrent suppuration (IRS). The epidemiology of the disease is not well described, with previous studies reporting prevalence estimates from 0·00033% to 4%., Objective: To determine the prevalence of IRS in a large population-based survey., Methods: Data were obtained from a general cross-sectional population study in Denmark. A validated self-administered questionnaire was used to identify IRS. Persons with the combination of outbreaks of 'boils' during the last 6 months in predefined areas and a minimum of two boils were identified., Results: A total of 16 404 adults aged 30-89 years provided data and the overall prevalence of IRS was found to be 2·10% [95% confidence interval (CI) 1·88-2·32]; in men it was 1·58% (95% CI 1·29-1·86) and in women 2·56% (95% CI 2·21-2·86). No data for adults aged 20-29 years were included. The prevalence declined with age. The majority of cases (72·9%) had a body mass index of ≥ 25 kg m(-2) and 77·7% were current or ex-smokers. The mean number of inflamed lesions was 6·5 (range 2-67) during the last 6 months. The lesions affected mostly the genitalia (43·4%) and groin (39·8%) for women and 'other places' (not specified) (78·8%) for men., Conclusions: Data on IRS suggest that HS may be more prevalent than previously suggested, and the prevalence may be comparable to other major dermatoses, e.g. psoriasis. However, as no physician examination was done, the risk of recall and information bias is a major limitation., (© 2013 British Association of Dermatologists.)

Background: Estimates of the prevalence of hidradenitis suppurativa (HS) range from 0.33% to 4%. Further epidemiological data are therefore needed. Because of the hidden nature of the disease, physical screening may be cumbersome and questionnaire-based screening may be more appropriate., Objectives: To establish the sensitivity (SE), specificity (SP) and positive predictive value (PPV) of simple diagnostic questions used in HS., Methods: Potential diagnostic questions regarding HS were identified and sent to 85 patients with HS and to an age- and sex-matched control group randomly selected among outpatients not being treated for HS. All respondents were recruited in the Department of Dermatology in Roskilde Hospital., Results: In total, 74 of 85 patients with HS (87%) returned the questionnaire (61 women and 13 men). Of these, 72 reported repeated outbreaks of painful nodules or boils in locations typical for HS compared with 13 patients in the control group. The SE ranged from 0.92 to 0.97, the SP from 0.82 to 0.86 and the PPV from 0.85 to 0.89. Boils appeared significantly more often in patients with HS, who also reported significantly greater suffering from their lesions., Conclusions: The high diagnostic power suggests that all the questions are potentially useful. The clear symptomatology of HS may be a key factor. It is suggested that further improvement may be achieved by adding definitions of pimples, nodules or boils to future questionnaires. Similarly, adding the possibility to indicate uncommon locations, duration and quality-of-life impairment may benefit the diagnostic power.

The morbidity of hidradenitis suppurativa can be considerable, but little is known about its epidemiology. Our purpose was to describe the one-year and point prevalences of hidradenitis suppurative and its potential precursor lesions. We obtained the histories and examined an unselected sample (599 persons) of the general population (one-year prevalence), and we performed physical examination for a consecutive sample of 507 persons undergoing screening for sexually transmitted diseases (point prevalence). The point prevalence was 4.1% (95% confidence interval [CI] = 3.0-6.0) on the basis of objective findings. The one-year prevalence of hidradenitis was 1.0% (CI = 0.4-2.2) on the basis of subject recollection only. The patients in the sample on which the point prevalence is based were younger than those in the unselected sample of the general population (p < 0.001). Hidradenitis was significantly more common in women (p = 0.037), which may result from a female preponderance of genitofemoral lesions (odds ratio [OR] = 5.4; CI = 1.5-19.3). No sex difference was found in the prevalence of axillary lesions. Hidradenitis suppurativa is significantly more common than hitherto estimated. A female preponderance of patients is confirmed, except for patients with axillary lesions. Additional longitudinal studies are necessary to assess the importance of potential precursor lesions such as non-inflamed nodules or comedones.

The general characteristics of patients with hidradenitis suppurativa have not been previously described in detail. Although rare complications of the disease have been described, little is known of the average impact of hidradenitis suppurativa. We have now aimed to describe the general characteristics of the disease and its impact on patients with an established diagnosis of hidradenitis (n = 68) and compare these with those of an unselected general population sample (n = 523). Pierced earlobes were more common in patients than in the controls (P < 0.02). Female patients were younger (P = 0.0002) and better educated (P < 0.0001), and fewer had been pregnant (P = 0.0006). The median number of treatments prior to referral was two, and an average of 2.7 work days/patient per year were lost due to hidradenitis. The self-reported health of patients was significantly inferior to that of the general population (P < 0.001), mainly because of soreness and restriction of movement. Low-grade hidradenitis suppurativa therefore has a considerable impact on the health of patients. Previously implied associations with the disease such as the use of cosmetics or oral contraceptives, menstrual cycle and body mass index (BMI) were not confirmed in our study, although they may influence the course pre-existing disease.

Background: The morbidity of hidradenitis suppurativa can be considerable, but little is known about its epidemiology., Objective: Our purpose was to describe the 1-year and point prevalences of hidradenitis suppurativa and its potential precursor lesions., Methods: We obtained the histories and examined an unselected sample (599 persons) of the general population (1-year prevalence), and we performed physical examinations for a consecutive sample of 507 persons undergoing screening for sexually transmitted diseases (point prevalence)., Results: The point prevalence was 4.1% (95% confidence interval [CI] = 3.0-6.0) on the basis of objective findings. The 1-year prevalence of hidradenitis was 1.0% (CI = 0.4-2.2) on the basis of subject recollection only. The patients in the sample on which point prevalence is based were younger than those in the unselected sample of the general population (p < 0.001). Hidradenitis was significantly more common in women (p = 0.037), which may result from a female preponderance of genitofemoral lesions (odds ratio [OR] = 5.4; CI = 1.5 - 19.3). No sex difference was found in the prevalence of axillary lesions., Conclusion: Hidradenitis suppurativa is significantly more common than hitherto estimated. The female preponderance of patients is confirmed, except for patients with axillary lesions. Additional longitudinal studies are necessary to assess the importance of potential precursor lesions such as noninflamed nodules or comedones.