Abstract: Objective: To investigate the clinical characteristics and risk factors of infections within 3 months after autologous stem cell transplantation (ASCT) in patients with systemic light⁃chain (AL) amyloidosis. Methodology: A total of 385 patients with AL amyloidosis who underwent ASCT at the National Clinical Research Center for Kidney Diseases from March 2010 to March 2025 were included. Infection rates and pathogen profiles within 3 months post⁃ASCT were analyzed, along with treatment outcomes. Univariate and multivariate logistic regression analyses were used to identify risk factors. Results: Of 385 patients, 144 developed 148 infections within 3 months, with an infection incidence rate of 38.4%. Pre⁃engraftment infections accounted for 75.7% of the total, and post⁃engraftment for 24.3%. Common pre⁃engraftment infection sites were skin/soft tissue (14.6%), gastrointestinal tract (12.2%), and bloodstream (10.6%), while 48.8% of patients only presented with infectious fever without a clear site. Post⁃engraftment infections mainly involved the lungs (32.4%), skin/soft tissue (29.7%), and upper respiratory tract (13.5%). Escherichia coli, Candida species, and herpes simplex virus were predominant pre⁃engraftment pathogens, while varicella⁃zoster virus was common post⁃engraftment. Multivariate analysis identified age (≥55 years), hypoalbuminemia (<30 g/L), severe mucositis, and prolonged neutropenia (>7 days) as independent risk factors. Conclusion: Infection rates were higher in the pre⁃engraftment period, with distinct differences in infection sites and pathogen distribution between the two stages. Age ≥55 years, hypoalbuminemia, severe mucositis, and prolonged neutropenia were risk factors for early infections post⁃ASCT.

Key words: autologous stem cell transplantation, systemic light chain amyloidosis, infection, risk factor