High Incidence of Stroke in ANCA-associated Vasculitis due to high platelet count

The incidence of stroke was higher in the first three months of diagnosis in ANCA-associated vasculitis patients when compared to the general population as per a new study. Age, creatinine levels, and platelet counts were the factors associated with increased risk of stroke. The study results were published in the journal Rheumatology. 

ANCA-associated vasculitis (AAV) is a collective term for a group of autoimmune diseases causing systemic inflammation. It is characterized by the inflammation of the small blood vessels, including granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Previous literature has shown an increased risk of cardiovascular events in patients with AAV but there has been meager research on the association of stroke with AAV. Hence researchers from Lund, Sweden, and Cambridge conducted a population-based cohort study to determine the incidence rate, predictors, and outcome of stroke in a population-based cohort of individuals with ANCA-associated vasculitis (AAV).  

Nearly 325 people from a specific area in Sweden were identified from 1997 to 2016. Using data from The Skne Healthcare registration (SHR), and Riksstroke, a national Swedish stroke registration were used to identify patients who had suffered a stroke. Diagnosis of stroke in AAV patients was confirmed by reviewing the SHR. 1000 person-years of follow-up were used to compute the incidence rate of stroke. The standardized incidence ratio (SIR) of stroke was calculated using data from the Swedish general population. The investigation of stroke predictors and survival was done using Cox regression analysis. 

Findings: 

• Twenty-five subjects (8%) suffered a stroke during 2206 person-years of follow-up.
• The incidence rate of stroke in AAV was 11.3/1000 person-years (95% CI 6.9, 15.8).
• Patients with AAV showed an increased risk of stroke compared with the general population, with a greater risk for those <65 years of age.
• Higher platelet count at AAV diagnosis was an independent predictor of stroke.
• There were no differences in survival or other outcome measures between AAV patients with and without stroke. 

Thus, a three times high risk of stroke incidence was found in AAV compared to the general population in Sweden mainly during the initial 3 months of diagnosis. Age at diagnosis, high creatinine, and high platelet count were associated with an increased risk of stroke. 

Further reading: High Risk of Stroke in ANCA-associated Vasculitis. A Population-Based Study. Rheumatology. 2023;62(8):2806-2812.