The prevalence and risk of mortality associated with antimicrobial resistance within nosocomial settings-a global systematic review and meta-analysis of over 20,000 patients.

Background: Bacterial antimicrobial resistance (AMR) is a leading cause of death globally. However, there has been no data synthesis on whether it influences mortality within hospital settings. We conducted a systematic review and meta-analysis to quantify the prevalence and risk of mortality associated in hospitalised patients with AMR, compared to patients with infections not classified as AMR. Methods: Databases (MEDLINE, EMBASE, and Cochrane library) were searched from inception up to 14th April 2025 for studies that reported the prevalence of AMR in patients who acquired infections in hospitals and mortality (PROSPERO CRD42023420609). We calculated pooled prevalence estimates of AMR as well as unadjusted and adjusted estimates of the effect of AMR on mortality using a random-effects model. Study quality was assessed using the Joanna Briggs Quality Appraisal Tool, risk of bias using DOI plots and LFK index and certainty of evidence of mortality using GRADE criteria. Findings: We identified 34 studies (20,658 patients with resistant organisms) from 18 countries-namely the USA, China, the UK, Canada, Israel, Japan, Malaysia, Korea, Brazil, and Singapore. Of these, 33 were observational studies whilst two studies (one observational study and one purely modelling study) mechanistically modelled risk of mortality in relation to transmission. No studies were conducted in the African subcontinent, the Middle-East, Russia, and India. The prevalence of AMR was high in patients in hospital (pooled prevalence: 36.5%, 95% CI: 29%-44%, Interpretation: AMR is highly prevalent within hospital settings globally and associated with increased in-hospital mortality. Crucially, no data was identified from the India subcontinent, African subcontinent, the Middle East, and Russia, and only two studies used mechanistic modelling to explore how transmission of AMR affects mortality. Further research is required, particularly in underrepresented regions to inform interventions aimed at reducing both AMR transmission and its related mortality within hospital settings. Funding: Pacific Life.