Epidemiology and treatment of Adamantiades-Behçet's disease in Germany: A healthcare claims database study

Adamantiades-Behçet's disease (ABD) is a rare, chronic, relapsing, multisystem vasculitis, with a reported prevalence of 0.9 out of 100,000 population in Germany in 2012. However, more recent epidemiological data are lacking. To estimate the prevalence and incidence of ABD in Germany and assess associated comorbidities and current treatment patterns. This retrospective cohort study used claims data from the anonymized Institute for Applied Health Research Berlin (InGef) research database. Cohorts were formed for the observation years 2016, 2017 and 2018, using data from 2013 to 2018 (allowing for a 3-year baseline period for incidence data). The study population included patients ≥18 years old with a diagnosis of ABD (ICD-10 diagnostic code M35.2), covered under the statutory health insurance system and in the InGef research database, with continuous insurance in the observation year and baseline period. We descriptively evaluated prevalence (≥2 outpatient ABD diagnoses in different quarters/≥1 main inpatient diagnosis in the observation year), incidence (no confirmed outpatient/inpatient diagnosis in the baseline period), comorbidities reported during the study and ABD-related medications. We identified 300, 303 and 329 patients diagnosed with ABD in 2016, 2017 and 2018, respectively, with fewer than half (122/300 [40.7%], 127/303 [41.9%] and 150/329 [45.6%]) prescribed ≥1 disease-related medication. In the treated population, ABD prevalence was 3.9 (2016), 4.1 (2017) and 4.7 (2018) per 100,000 population; annual ABD incidence was 0.5 per 100,000 population in 2016 and 2017 and 0.6 per 100,000 population in 2018. The most commonly reported comorbidities in patients diagnosed with ABD were dorsalgia (an indicator of possible misdiagnosis), disorders of refraction and accommodation, and essential (primary) hypertension. Prednisolone, colchicine and azathioprine were the most commonly prescribed treatments for ABD, with approximately 15% of patients taking >1 medication for ABD. The reported data provide evidence that ABD remains a rare disease in Germany.