Assessment of bacterial infection risk factors and related complications in newly diagnosed multiple myeloma: A retrospective cohort analysis

BACKGROUND: Patients with multiple myeloma are at risk of developing infections early in their disease course, but the role of antibacterial prophylaxis during induction therapy remains controversial. This study aims to assess bacterial infection risk factors and complications in newly diagnosed multiple myeloma. METHODS: This retrospective chart review included all patients diagnosed and treated for multiple myeloma at a tertiary care cancer center in Riyadh, Saudi Arabia between 2015 - 2023. The primary endpoint was to identify bacterial infection risk factors within the first 6 months of diagnosis. Secondary endpoints included evaluating infection-related hospitalization burden, mortality rate, and resistance patterns of bacterial isolates. Multivariable logistic regression was used to explore predictors of infection. A post-hoc analysis was conducted using multivariable cox proportional hazards regression was used to explore predictors of mortality. RESULTS: A total of 112 patients were included in this study; 56% were male, and approximately 50% of patients were 65 years or older at diagnosis. Fifty percent of patients had disease with high-risk features. Patients with cardiac disease and smokers were more likely to develop infections early in their disease course and sustain higher risk of infection over time. The average length of stay for infection-related hospitalizations within the first 6 months was 7.7 days. Almost 10% deaths occurred within the first year, with cardiac disease being a significant predictor of mortality. Finally, majority of bacterial isolates were obtained from urine samples, 25% of which were multi-drug resistant. CONCLUSIONS: Newly diagnosed multiple myeloma (NDMM) patients with cardiac disease and smokers were at higher risk of developing infections early in their treatment course and may benefit from tailored antimicrobial prophylaxis. Our results highlight the significant morbidity associated with infections in NDMM.