Characteristics and Risk Factors of Infections among Patients with Autoimmune Bullous Diseases: A Retrospective Single-Center Study in China

Background::Since infections can lead to adverse outcomes in autoimmune bullous diseases (AIBD), this study aimed to analyze infection characteristics in AIBD, predict infection risk factors and provide probable suggestions to infection prevention, which will spot a light on early discovery and prevention of infections in AIBD patients.Methods::This is a retrospective study of the medical records of inpatients diagnosed with AIBD at the Department of Infectious Diseases and Dermatology, Huashan Hospital from January 2017 to December 2021. We collected patients’ clinical manifestations and laboratory examination results. Risk factors for infections were evaluated using multivariate logistic regression.Results::A total of 263 AIBD patients were included in the study. The overall incidence of infection was 42.2% (111/263). Pemphigus had a higher infection rate (74/142, 52.1%) than bullous pemphigoid (37/121, 30.6%). Among the patients with infections, 49.5% (55/111) had bacterial infections, 13.5% (15/111) had fungal infections, 2.7% (3/111) had virus infections, and 34.2% (38/111) had mixed infections. Staphylococcus aureus and Candida were the most common pathogens in localized infections, while Cryptococcus and Candida were predominant in systemic infections. In the multivariate logistic model, pemphigus (odds ratio [ OR] = 2.56, 95% confidence interval [ CI] 1.41-4.63), hypoalbuminemia ( OR = 3.78, 95% CI 1.68-8.50), and systemic glucocorticoid treatment ( OR = 4.67, 95% CI 2.51-8.68) were independent risk factors for infection in AIBD patients. Bullous pemphigoid ( OR = 3.99, 95% CI 1.03-15.45), high-dose (average > 24 mg/day) compared to low-dose (average ≤ 6 mg/day) and medium-dose (average 6-24 mg/day) systemic glucocorticoid treatment ( OR = 19.31, 95% CI 3.32-112.28, and OR = 5.71, 95% CI 1.37-23.79) were associated with increased risk factors of systemic infection in AIBD patients with systemic glucocorticoid treatment. A methylprednisolone dose averaging 14 mg/day over the past three months had a 75.0% positive predictive value for infections in AIBD patients. Conclusions::The incidence of infection in AIBD patients is high, with a broad spectrum of pathogens and infection locations. AIBD patients undergoing systemic glucocorticoid treatment, especially those receiving high doses in the previous three months, should be cautious about infection.