Determinants of in-hospital mortality within 48 hours of admission to the Emergency and Urgent Care Department at University Teaching Hospital, Lusaka, Zambia: a retrospective cross-sectional study

BackgroundThe emergency department (ED) serves as a critical entry point into hospital care and a sentinel indicator of health system performance. In-hospital mortality within 48 hours of ED admission represents acute care failures that are often preventable yet remain poorly characterized in sub-Saharan African (SSA) settings. This study aimed to identify the demographic, clinical, and hospital-related determinants of in-hospital mortality within 48 hours of admission to the Emergency and Urgent Care Department at the University Teaching Hospital (UTH), Lusaka, Zambia. MethodsA retrospective cross-sectional study was conducted using 385 patient records from UTHs Emergency and Urgent Care Department for the year 2021. Data were extracted from the District Health Information System 2 (DHIS2) using simple random sampling. Descriptive statistics, univariate, and multivariable logistic regression analyses were performed using STATA 16.1 MP. Variables with p<0.20 in univariate analysis were retained for adjusted modelling. Multicollinearity was assessed via variance inflation factors (VIF <5). Model fit was evaluated using the Hosmer-Lemeshow goodness-of-fit test and receiver operating characteristic (ROC) analysis. ResultsOf 385 patients, 175 (45.5%) died within 48 hours of admission. Patients who died were older (median age 45 vs. 37.5 years, p<0.001). In multivariable analysis, three variables were independently associated with 48-hour mortality: pulse rate (aOR = 0.98, 95% CI: 0.95-1.00, p = 0.036), Glasgow Coma Scale (GCS) score (aOR = 0.75, 95% CI: 0.63-0.90, p = 0.002), and out-of-hours admission between 00:00-07:59 (aOR = 11.44, 95% CI: 1.19-109.96, p = 0.035). Age was a significant predictor in univariate analysis but not in the adjusted model, indicating confounding. The model demonstrated good discriminatory ability (AUC = 0.81). ConclusionsReduced pulse rate, lower GCS score at admission, and out-of-hours presentation are independent determinants of 48-hour in-hospital mortality at UTH. These findings underscore the need for enhanced vital sign monitoring protocols, targeted staffing during overnight hours, and improved risk stratification tools in resource-constrained emergency care settings. The wide confidence interval for the time-of-admission finding warrants cautious interpretation and validation in future prospective studies.