Weight Gain Following a Diagnosis of Anti-neutrophil Cytoplasm Antibody-Associated Vasculitis

ObjectivesPatients with anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) are at increased long-term risk of cardiometabolic diseases. The prevalence of obesity in AAV has not been well documented. We aimed to characterise change in body weight following a diagnosis of active AAV and to determine the risk factors for this. MethodsWe examined data from a single-centre registry of patients with AAV, diagnosed between 2003 and 2023. We evaluated changes in body weight and BMI following diagnosis. Using linear regression, we identified factors contributing to an increase in BMI at six-months. Logistic regression was used to define predictors for obesity at six-months. ResultsTwo-hundred and fifteen patients with active AAV were included in the analysis. Patients experienced a mean gain in body weight of 5.2% in the first six-months; this was maintained for at least two-years. 64.1% of patients were overweight or obese at six-months. Weight gain was greater following first presentation of AAV compared to relapsing disease. Baseline factors associated with an increase in BMI at six-months included higher eGFR ({beta}=0.70 [0.36-1.03], P<0.001) and earlier year of presentation ({beta}=0.38 [0.08-0.69], P=0.008). Higher eGFR (aOR=1.36 (1.08-2.72), P<0.001) and baseline BMI (aOR=2.57 (1.81-3.64), P<0.001) were associated with an increased likelihood of obesity at six-months. ConclusionWeight gain is common following a diagnosis of active AAV. This is less pronounced than it was two-decades ago. Better kidney function and higher baseline BMI are associated with a greater risk of being obese at six-months. Management of AAV should include risk mitigation for developing an unhealthy high BMI. Key messagesO_LIWeight gain and an unhealthy high BMI are prevalent following diagnosis of active AAV. C_LIO_LIHigher baseline eGFR is associated with greater weight-gain in the first six-months following diagnosis. C_LIO_LIWeight gain is less pronounced following treatment of relapsing disease compared to initial presentation. C_LI