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

e19533 Background: Patients with newly diagnosed multiple myeloma (NDMM) are at risk of developing early infections within 3-6 months, contributing significantly to infection related morbidity and mortality. Current guideline recommendations are inconsistent regarding early antimicrobial prophylactic therapy in patients with NDMM. This study aims to identify risk factors associated with increased infection rates to identify NDMM patients who may benefit from antimicrobial prophylaxis, and to assess the burden of infection related complications in a large cancer center. Methods: A retrospective cohort study of patients with NDMM who were diagnosed and treated at a tertiary academic hospital in Saudi Arabia between 2015 to 2023. Data on patient characteristics, disease risk stratification, infection related hospital admissions and mortality were collected through the electronic medical record. Statistical analysis was conducted using SPSS version 26 to examine the relationship between patient risk factors and infection rates. Descriptive statistics, Chi-square tests/Fisher’s exact tests were used to identify significant predictors of infection-related outcomes and assess the prevalence of multi-drug-resistant organisms. Results: We identified 112 eligible NDMM patients to include in this study, 43% of included patients were females, median age at diagnosis was 61 years (IQR 52-73), 43% of patients had an ECOG performance of 0-2 status at time of diagnosis, 47% of patients had an ECOG >3 and 10% had no documented ECOG score. In terms of disease risk stratification, 53% had an international staging system (ISS) stage III and 28.5% had high risk cytogenetics. Risk factors associated with higher rates of infection include cardiac disease at baseline, and the following at the time of diagnosis: serum beta 2 macroglobulin ≥ 5.5 mg/L, elevated lactate dehydrogenase, hemoglobin < 10 g/dl, elevated serum creatinine ≥2 mg/dl and patients on hemodialysis. We identified 11 (9.8%) patients who passed away within the first year from infection related complications, 6 (5.3%) of which died within the first three months. Positive cultures were identified in 85 patients, with the majority obtained from urine samples (43 isolates, 44.9%), followed by blood cultures (29 isolates, 30.2%). Escherichia coli was the most frequently isolated species (25 isolates, 25.8%), followed by Pseudomonas aeruginosa (16 isolates, 16.5%) with multidrug-resistant organisms (MDROs) accounting for 25% of isolates. Conclusions: Infection related complications and increased prevalence of MDROs represent a challenge for our NDMM patient population. Patients with ISS stage III, anemia, renal or cardiac disease may benefit from antimicrobial prophylaxis early in their disease course. Prospective studies are needed to confirm the benefit of antimicrobial prophylaxis in this patient population.