Diagnostic delay in hidradenitis suppurativa is a global problem.

DEAR EDITOR, Hidradenitis suppurativa (HS) is clinically defined with recognized diagnostic criteria and recognizable physical characteristics. Untreated, the disease causes significant morbidity. The prevalence varies between 0 0003% and 4% depending on the study population. Estimates from insurance databases suggest a prevalence of < 0 1%. This variation strongly suggests a significant selection bias or misclassification, and it may be speculated that not all patients present for care. This is reinforced by clinical experience and published evidence indicating a significant delay in diagnosis. This study explores the delay in diagnosis for patients with HS on an international level. The study (survey) was conducted in 2013. Observational data were collected during routine visits or extracted from case records. Because of the simple and obvious symptomatology of recurrent painful lesions present in restricted welldefined areas of the body, patients’ self-reported history was considered valid regarding onset of symptoms. Consecutive patients with HS and psoriasis were included from each participating centre during a period of 4 months or less. The data were anonymized by removing any names, addresses and social security numbers, and included age, sex, age at disease onset, age at diagnosis, delay in diagnosis, time from onset of symptoms to first physician contact, age at first medical contact, number of physicians seen prior to the diagnosis, family history and disease severity. If the diagnosis was made by a primary care physician or by a specialist other than a dermatologist prior to seeing a dermatologist, this was recorded as the date of the diagnosis. Individual centres were responsible for and obtained any locally required permissions and signed informed consent forms, for example ethics committee approval, in accordance with national registry and data protection rules. Patients diagnosed with HS or psoriasis (and confirmed by the investigator) were included. The primary outcome was quantification of the delay in diagnosis. Additionally, documentation was made of both the delay in visiting a physician (and so gaining access to specialist treatment) and the relative delay in diagnosis of HS compared with psoriasis with/without a family history. The severity of HS was determined by Hurley’s staging criteria: stage I, mild; stage II, moderate and stage III, severe. In patients with psoriasis, severity was evaluated by the Psoriasis Area and Severity Index: score < 7, mild; 7–12, moderate and > 12, severe. The t-test, Wilcoxon rank sum test and v-test were used where appropriate. Univariate and multivariate logistic regression analyses were used to identify factors predictive of significant diagnostic delay. Diagnostic delay > 2 years was defined as significant. Diagnosis, sex, age of onset, family history and disease severity were selected as potentially important