Iron overload is a major risk factor for severe infection after autologous stem cell transplantation: a study of 367 myeloma patients

We evaluated the risk factors for infection of 367 consecutive myeloma patients who underwent high-dose melphalan and autologous stem cell transplantation ( ASCT). Examination of bone marrow iron stores ( BMIS) prior to ASCT was used to evaluate body iron stores. Other variables included age, sex, active smoking, myeloma remission status, severity of mucositis and duration of severe neutropenia post-ASCT ( <100 absolute neutrophils counts ( ANC)/mu l). Median age was 56 years; 61% of patients were males. 140 episodes of severe infections occurred in 116 patients, including bacteremia ( 73), pneumonia ( 40), severe colitis ( 25) and bacteremia with septic shock ( two). The infection incidence per 1000 days at risk was 45.2. Pre-ASCT risk factors for severe infection by univariate analysis were increased BMIS ( OR 2.686; 95% CI 1.707-4.226; P<0.0001), smoking ( OR 1.565; 95% CI 1.005-2.437; P=0.0474) and male gender ( OR 1.624; 95% CI 1.019-2.589; P=0.0414). Increased BMIS ( OR 2.716; 95% CI 1.720-4.287; P<0.0001) and smoking ( OR 1.714; 95% CI 1.081-2.718; P=0.022) remained significant by multivariate analysis. Duration of ANC <100 mu/l ( OR 1.129; 95% CI 1.039-1.226; P=0.0069 and OR 1.127; 95% CI 1.038-1.224; P=0.0045 by both univariate and multivariate analysis, respectively) was the only post-ASCT risk factor for infection. Increased pre-transplant BMIS and smoking are significant predictors of severe infection after myeloablative chemotherapy followed by ASCT in myeloma patients.