Clinical characteristics, risk factors and predictors of Parvovirus B19 infection in patients with autoimmune rheumatic inflammatory diseases: A nested case-control study.

This nested case-control study explored the clinical features and risk factors of Parvovirus B19 (B19V) infection in autoimmune rheumatic inflammatory disease (AIIRD) patients. A total of 86 B19V-positive cases and 172 matched controls were analyzed. Chronic liver diseases, cardiovascular diseases, a higher number of total infections, and the use of Mycophenolate Mofetil (MMF) were associated with an increased risk of B19V infection, whereas Iguratimod (IGU) was identified as a protective factor. Anemia, pneumonia, fever, myalgia, and hepatitis were significantly more common in B19V-infected patients, who were also more likely to experience varying degrees of cytopenia, particularly pancytopenia. Secondary hemophagocytic syndrome potentially attributable to B19V infection was observed in the case. Laboratory results showed lower blood cell counts and electrolytes, and higher anti-histone antibody positivity. Serum calcium, complement C4, and IgM were identified as key predictors in logistic and Lasso regression models. TRIAL REGISTRATION: Chinese Clinical Trial Register; https://www.chictr.org.cn/; ChiCTR2400089902.