P039 Epidemiology and clinical presentation of cutaneous vasculitides in a regional cohort study 2011–20

Abstract Cutaneous vasculitides (CVs) are autoimmune and autoinflammatory conditions affecting small blood vessels in the skin. This can cause urticaria, petechiae or purpuric papules. Few studies on the epidemiology and clinical presentation of CVs exist. This 2011–20 retrospective regional cohort study identified patients with biopsy-proven CV from pathology reports in a single secondary centre covering a total patient exposure of 6 631 136. Age-standardized incidence rates and age-specific rates were calculated using the European 2013 standard population and are reported per 100 000 person-years (PY) alongside 95% confidence intervals. The Office for National Statistics census 2011 postcode data, 2021 census regional population data and annual estimates were used to estimate representative postcode population counts. Electronic patient records (EPRs) were used to summarize potential triggers and investigation results. The difference in incidence were compared using χ2-tests. Histologically confirmed cases of CV were diagnosed in 257 patients over the age of 18 years (56.0% female) in this regional cohort between 2011 and 2020. Diagnoses were leucocytoclastic vasculitis (58.4%), IgA vasculitis (15.2%), urticarial vasculitis (10.1%), eosinophilic granulomatosis with polyangiitis (1.9%), polyarteritis nodosa (0.8%) and vasculitis ‘not otherwise specified’ (13.6%). The median age at diagnosis was 61 years (range 19–91). The 2011–20 age-standardized incidence rate was 3.8 (95% confidence interval 0.28–0.35) per 100 000 PY for the whole population. The CV age-specific rates rose steadily with age, with a large increase in people aged > 60 years. The age-specific rates also showed a bimodal female-to-male distribution. For those aged < 50 and > 75 years, female patients had higher rates than male patients. However, this difference was not statistically significant (P > 0.05). The EPRs of 107 patients included documentation about new medications. New medications within 6 months of symptom onset were reported for 63 of 107 (58.9%) patients, 34 of 63 (54%) of whom had been started on antibiotics. Of 129 EPRs including documentation on recent illness, 88 patients (68.2%) had an infection or intercurrent sepsis. The biochemistry results were available for 220 patients. Of these, urea and creatine were raised for 34 (15.5%) and 35 (15.9%) patients, respectively. C-reactive protein and erythrocyte sedimentation rate were elevated in 126 of 192 (65.6%) and 62 of 165 (37.6%) patients, respectively. Antineutrophil cytoplasmic antibody was tested in 192 patients and positive in 19 (9.9%). CV is uncommon and there is a lack of epidemiological studies in the literature, perhaps because cases are not easily identified through routinely collected healthcare data. Blood tests were generally unremarkable except for raised C-reactive protein, and commonly found triggers included infection and medications, as expected. Our data are essential to support future evidence-based research into this condition.