Prevalence of hidradenitis suppurativa among patients with Down syndrome: a population-based cross-sectional analysis.

BACKGROUND: Hidradenitis suppurativa (HS) has been linked to Down syndrome (DS). OBJECTIVES: To determine whether patients with DS have a higher prevalence of HS, and whether the diagnosis of HS occurs at an earlier age for these patients. METHODS: A cross-sectional analysis was performed for a population sample of 11 936 patients with DS and 16 813 290 patients without DS. The primary outcome was the diagnosis of HS. Systemized Nomenclature of Medicine-Clinical Terms were used to identify patients with DS and HS. We used logistic regression models and significant interaction terms to evaluate the relationship between DS and HS. We also compared the proportion of incident HS cases within 5-year age groups to determine whether patients with DS had received an earlier diagnosis of HS. RESULTS: Prevalence of HS among patients with DS was 2·1%, compared with 0·3% for patients without DS (P < 0·001). HS prevalence was greatest among patients with DS who were aged 18-29 years. After controlling for age, sex and obesity, there was no difference in the prevalence of HS between female and male patients with DS or between white and nonwhite patients with DS. Compared with patients without DS, patients with DS had increased odds of HS in unadjusted [odds ratio (OR) 7·84, 95% confidence interval (CI) 6·93-8·88] and adjusted (OR 5·24, 95% CI 4·62-5·94) analyses. HS was diagnosed by the age of 29 years in 81·8% of patients with DS, compared with 34·0% of patients without DS (P < 0·001). CONCLUSIONS: HS is strongly associated with DS across demographic subgroups and may present earlier in life for these patients.

Incidence of hidradenitis suppurativa among tobacco smokers: a population-based retrospective analysis in the U.S.A.

BACKGROUND: The relationship between tobacco use and hidradenitis suppurativa (HS) is controversial. OBJECTIVES: To determine the incidence of HS among tobacco smokers. METHODS: Retrospective cohort analysis identifying incident HS cases among adult tobacco smokers and nonsmokers sampled from a demographically heterogeneous population-based sample of over 50 million unique patients across all census regions in the U.S.A. RESULTS: We identified 3 924 310 tobacco smokers, which included 7860 patients newly diagnosed with HS. Tobacco smokers diagnosed with HS were most commonly aged 18-39 years (3795 of 7860; 48·3%), women (5640 of 7860; 71·8%), white (5200 of 7860; 66·2%) and those with body mass index (BMI) ≥ 30 (5690 of 7860; 72·4%). Overall incidence of HS was 0·20% (7860 of 3 924 310) among tobacco smokers and 0·11% (8430 of 8 027 790) among nonsmokers (P < 0·001). Incidence was greatest among tobacco smokers who were aged 30-39 years (0·35%), women (0·28%), African Americans (0·46%) and those with BMI ≥ 30 (0·33%). The overall adjusted odds of developing HS was 1·90 (95% confidence interval 1·84-1·96) among tobacco smokers, compared with nonsmokers (P < 0·001). HS incidence among tobacco smokers remained increased within each demographic subgroup. CONCLUSIONS: Incidence of HS appears to be doubled among tobacco smokers. These findings may support evidence-based counselling efforts for the cessation of smoking in populations at risk for HS.