Abstract Background Community-acquired pneumonia (CAP) is a major cause of global hospitalization and mortality. Chronic kidney disease (CKD) patients are particularly vulnerable due to immune dysfunction and frequent comorbidities. The microbial etiology and prognostic factors for in-hospital mortality in CKD patients with CAP remain inadequately characterized. Methods This retrospective study enrolled 1277 hospitalized CKD patients with CAP from October 2017 to July 2025. Demographic, clinical and laboratory data were systematically collected from electronic medical records. Microbiological diagnosis integrated culture, nucleic acid testing, and metagenomic next-generation sequencing from respiratory and blood samples. The primary outcome was all-cause in-hospital mortality. Statistical analyses included UpSet plots, chi-square/non-parametric tests, Kaplan-Meier survival curves with log-rank test, and machine learning (LASSO regression, Random Forest, support vector machine, XGBoost) with Cox regression for poor prognostic factor identification. Results A causative pathogen was identified in 35.8% of patients (n = 457). The five most frequently isolated pathogens were Klebsiella pneumoniae (21.9%), followed by Candida albicans (21.4%), Acinetobacter baumannii (16.4%), Escherichia coli (11.8%) and Pseudomonas aeruginosa (11.6%). The rates of in-hospital all-cause mortality was 12.3% . Survival analysis demonstrated that severe pneumonia and severe impaired renal function (eGFR 30 mL/min/1.73 m²) were significantly associated with in-hospital mortality. Additionally, the presence of comorbidities such as heart failure, VTE, anemia, or thrombocytopenia further elevated the mortality risk. Multivariate analysis confirmed that sCRP 71.1(mg/L) (HR = 1.14, 95% CI 1.01 - 1.99), PCT 0.58 (ng/mL) (HR = 1.84, 95% CI 1.29 - 2.63), Urea 13.5 (mmol/L) (HR = 1.62, 95% CI 1.14 - 2.30), LDH 288.5 (U/L) (HR = 2.97 95% CI 2.13 - 4.13), Alb 32.5 (g/L) (HR = 1.89, 95% CI 1.35 - 2.66), Lac 2.49 (mmol/L) (HR = 2.15, 95% CI 1.51 - 3.05) and Thrombocytopenia (HR = 1.89, 95% CI 1.36 - 2.64) were independently associated with in-hospital mortality. Analysis of pathogen-specific outcomes revealed that Pseudomonas aeruginosa, Candida albicans, and Acinetobacter baumannii were associated with higher mortality in severe pneumonia patients, while Candida albicans additionally conferred an increased risk in patients with severe renal impairment. Conclusions This study defines a unique pathogen profile in CKD-CAP patients, highlighting the prognostic significance of Candida albicans. Key poor prognostic factors for in-hospital mortality include severe pneumonia, severe renal impairment, specific comorbidities, and distinct laboratory abnormalities. Early recognition and personalized management targeting these factors are essential for improving outcomes. This abstract is funded by: NA
He et al. (Fri,) studied this question.