Pretreatment lymphopenia, poor performance status, and early courses of therapy are risk factors for severe bacterial infection in patients with multiple myeloma during treatment with bortezomib-based regimens

The aim of this study was to identify the risk factors associated with severe bacterial infection (SBI) in multiple myeloma (MM) patients during treatment with bortezomibbased regimens. A total of 98 patients with MM were evaluated during 427 treatment courses. SBI occurred in 57.1% (56/98) of the patients and during 19.0% (81/427) of the treatment courses. In the multivariate analysis for the factors associated with the development of SBI in each treatment course, poor performance status (Eastern Cooperative Oncology Group ≥ 2, P < 0.001), early course of therapy (≤ 2 courses, P < 0.001), and pretreatment lymphopenia (absolute lymphocyte count < 1.0 × 10⁹/L, P = 0.043) were confirmed as independent risk factors. The probability of developing SBI were 5.1%, 14.9%, 23.9%, and 59.5% in courses with 0, 1, 2, and 3 risk factors, respectively (P < 0.001). In conclusion, we identified three pretreatment risk factors associated with SBI in each course of bortezomib treatment. Therefore, MM patients with these risk factors should be more closely monitored for the development of SBI during bortezomib-based treatment.