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.