A new study has assessed the current epidemiology of antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) in southern Sweden and found a stable incidence but rising prevalence.
The study, published in RMD Open, speculates that the increasing incidence may reflect improved management and treatment of ANCA, leading to longer survival.
“Epidemiological studies of rare diseases such as ANCA are needed to increase our understanding of etiological mechanisms and provide a basis for the planning and allocation of healthcare resources,” the authors wrote. “Due to changing incidence and prevalence around the world, we present an update comparing incidence and prevalence of ANCA over a 23-year period, and we also aim to assess possible seasonal variation in disease onset.”
The research team assessed 374 cases of ANCA diagnosed in an adult population over 14 municipalities in southern Sweden between 1997 and 2019. Case record review from a national health registry database was employed to determine the diagnosis of AAV, and point prevalence was determined on January 1, 2020.
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The results of the analysis revealed a stable incidence of ANCA over the 23-year follow-up period (30 cases per million) and an increasing prevalence, with the highest prevalence at 428 cases per million. Incidence increased with age.
The seasonal variation analysis showed that more patients were diagnosed with ANCA in the spring, particularly after respiratory infections. The authors speculate that winter respiratory infections could trigger the onset of ANCA in the spring.
The stable incidence with an increase in prevalence could represent improvements in clinician awareness, management, and survival. There has been a shift to less toxic therapies during the study period that supports this idea. The authors are encouraged by the results given that they are based on a large population-based sample without referral or selection bias and standard diagnostic classification for all the included patients.
Rathmann J, Segelmark M, Englund M, Mohammad AJ. Stable incidence but increase in prevalence of ANCA-associated vasculitis in southern Sweden: a 23-year study. RMD Open. Published online March 9, 2023. doi:10.1136/rmdopen-2022-002949