Multiple myeloma (MM) is a complex hematological malignancy, and understanding the factors influencing prognosis and survival is crucial for improving patient outcomes. This study aims to evaluate the factors influencing the prognosis and survival of MM patients by comparing the International Staging System (ISS) with the Revised ISS (R-ISS). MM patients treated and followed up between 2015 and 2023 were retrospectively analyzed. According to ISS staging, 21.4% of patients were categorized as Stage 1, 30% as Stage 2, and 48.6% as Stage 3. Similarly, the R-ISS system revealed 14.3% as Stage 1, while 42.9% were Stage 2, and 42.9% were Stage 3. These findings indicate that the two systems provide differing stage distributions, which could impact prognosis evaluation. Mortality occurred in 58.6% of patients during the follow-up period, highlighting the severity of the disease in later stages. Further analysis revealed that higher levels of red cell distribution width (RDW), phosphorus content, lactate dehydrogenase (LDH), and beta-2 microglobulin levels were significantly associated with mortality, emphasizing their potential as markers of poor prognosis. In particular, ISS Stage II and III, R-ISS Stage III, along with elevated RDW, total protein, phosphorus, and LDH, were identified as independent prognostic factors. These results suggest that while both staging systems offer valuable insights, specific biomarkers play a crucial role in refining prognostic accuracy. In conclusion, while the ISS system appears to provide more meaningful staging information in this cohort compared to R-ISS, integrating additional biomarkers like RDW and LDH could enhance the prediction of patient outcomes.

Background/Objectives: Bloodstream infections (BSIs) are a major cause of morbidity and mortality among patients with malignancy because of disease-related immune dysfunction, intensive chemotherapy, neutropenia, and frequent exposure to invasive procedures. This study aimed to characterize the microbiological profile and antimicrobial resistance patterns of BSIs in patients with malignancy and to identify clinical and laboratory factors associated with in-hospital mortality, explicitly treating ICU admission as an associated marker of critical illness rather than a predictor. Methods: This retrospective study included 191 clinically significant BSI episodes recorded between 2016 and 2025; record review confirmed that each included episode represented a different patient. Demographic characteristics, underlying diagnoses, comorbidities, chemotherapy history, catheter status, infection source, hematological and biochemical parameters, bloodstream pathogen category, antimicrobial susceptibility patterns, ward and intensive care unit (ICU) lengths of stay, and in-hospital mortality were evaluated. Categorical variables were compared using the chi-square or Fisher’s exact test, while continuous variables were analyzed using the Mann–Whitney U test. Multivariable logistic regression analysis was performed to identify factors independently associated with in-hospital mortality. Results: Of the 191 episodes, 96 (50.3%) occurred in female patients and 95 (49.7%) in male patients. Acute leukemia was the most common underlying diagnosis (n = 70, 36.6%). Blood cultures yielded Gram-negative organisms in 110 episodes (57.6%), Gram-positive organisms in 58 (30.4%), fungi in 19 (9.9%), and polymicrobial growth in 4 (2.1%). Among 168 episodes with interpretable bacterial antimicrobial susceptibility results, 99 (58.9%) met the study-defined composite resistance category was not equivalent to multidrug resistance. An indwelling catheter was present in 27 episodes (14.1%), ICU admission occurred in 25 (13.1%), and severe neutropenia (<500 cells/µL) was documented in 72 (37.7%). The median ward length of stay was 8.0 days (interquartile range, 5.0–14.0 days). In-hospital mortality occurred in 39 episodes (20.4%). Patients who died had significantly lower neutrophil, platelet, lymphocyte, and albumin levels and significantly higher urea and C-reactive protein levels than survivors (p < 0.01). In multivariable analysis, ICU admission (adjusted odds ratio [aOR], 18.94; 95% confidence interval [CI], 3.49–102.82; p < 0.001) and severe neutropenia (aOR, 6.06; 95% CI, 2.13–17.23; p < 0.001) were associated with in-hospital mortality. However, the wide confidence intervals, particularly for ICU admission, indicate substantial uncertainty in the magnitude of these associations. Conclusions: These estimates should therefore be interpreted cautiously, especially because the timing of ICU admission relative to BSI onset could not be established. Gram-negative organisms predominated among BSI episodes in patients with malignancy, and study-defined resistance phenotypes were frequent but heterogeneous. Severe neutropenia and ICU admission—analyzed specifically as a concurrent marker of critical illness rather than a predictor due to unestablished temporal sequence relative to BSI onset—were associated with in-hospital mortality. These estimates should be interpreted cautiously. Continuous surveillance of local pathogen distributions and resistance phenotypes, early identification of high risk patients, and institution-specific selection of empirical antimicrobial therapy may contribute to improved clinical outcomes.