Association between patient-to-nurse ratios in emergency departments and patient, staff, and organizational outcomes: a systematic review.

Clinical Snapshot

Key Findings

• P Value: Not explicitly reported in abstract; confidence intervals for both key results exclude the null, implying statistical significance at the 0.05 level.

• Effect Size: Adjusted odds ratio (aOR) = 0.68 for increased nurses per patient (mortality outcome, single cohort study). Cardiac arrest: RR = 1.33 for ≥8.5 patients/nurse vs. <8.5 patients/nurse (higher ratio associated with more cardiac arrests, i.e., worse outcome with lower staffing).

• Primary Outcome: In-hospital ED mortality: assessed in one cohort study (n=73 EDs). An increase in the number of nurses per patient was associated with reduced ED mortality.

• Nnt Or Sensitivity: No NNT calculated. No sensitivity or specificity data applicable. No pooled hazard ratio available. Individual study aOR = 0.68 (mortality) represents a 32% reduction in odds of ED mortality associated with increased nurse-to-patient ratio, but this is from a single observational study and should be interpreted with caution.

• Confidence Interval: Mortality: 95% CI 0.49–0.94. Cardiac arrest: 95% CI 1.05–1.67.

Clinical Application

Implementation of mandated or recommended nurse-to-patient ratios in EDs is feasible in principle but faces significant practical barriers including nursing workforce shortages, variable ED acuity and patient flow, cost implications, and the absence of an ED-specific evidence-based ratio threshold. The evidence does not yet support a specific numerical ratio mandate for EDs. Australia has a particular policy relevance for this review. Victoria introduced mandated nurse-to-patient ratios in acute wards under the Nurses and Midwives (Nursing and Midwifery) Act, and there is ongoing national debate about extending such mandates to EDs. The Australian College of Emergency Nursing (ACEN) and the Australasian College for Emergency Medicine (ACEM) have both highlighted ED nurse staffing as a patient safety priority. The RACGP and state health departments have recognised ED overcrowding and access block as systemic issues where staffing ratios may play a role. However, this review does not provide sufficient evidence to support a specific mandated ED ratio under Australian regulatory frameworks (TGA not applicable; no PBS implications). Any policy change would need to be informed by Australian-specific ED data, workforce modelling, and health economic analysis. Patients presenting to emergency departments across diverse healthcare systems. The findings are most directly applicable to EDs with moderate-to-high patient volumes where nurse staffing ratios are a modifiable organisational variable. Applicability to paediatric EDs, rural/remote EDs, or low-resource settings is uncertain.

Abstract

Background In many settings, studies have shown that establishing patient-to-nurse ratios has benefits for both patients and staff. Whether this is transposable to emergency department (ED) is unclear. Objective The primary objective was to assess the association between patient-to-nurse ratios in EDs and mortality. Design In this systematic review, a search strategy identified studies published in 2004-2025 in MEDLINE, Cochrane, and CINAHL. Two independent reviewers performed selection and data extraction, followed by a narrative synthesis. Outcomes The primary outcome was in-hospital mortality. Secondary outcomes were other patient outcomes, staff, and organizational outcomes. Results Of 2214 identified references, 17 studies were included and all of which were observational. The primary outcome was assessed in only one cohort study ( n  = 73 EDs), where an increase in the number of nurses per patient was associated with a reduction in ED mortality (adjusted odds ratio = 0.68; 95% confidence interval: 0.49; 0.94). An increase in the number of nurses per patient was also associated with a reduction in cardiac arrests (one study: relative risk = 1.33, 95% confidence interval: 1.05, 1.67 for ≥8.5 patients/nurse vs. <8.5) and medication errors (one of two studies), and an improvement in patient experience (two studies) and nurse satisfaction (one study). Mixed results were observed with regard to reducing length of stay (one of two studies), administration time (three of four studies) and the number of patients who left without being seen (three of four studies), while waiting time before diagnosis or treatment improved (three studies). Conclusion Although evidence is limited, several observational studies suggest that a higher nurse-to-patient ratio is associated with better patient, nurse, and ED organizational outcomes.

References

1. 1.Rivet, C., Amazouz, H., Gratacap, M., Delannoy, Q., Yordanov, Y., & Leblanc, J. (2026). Association between patient-to-nurse ratios in emergency departments and patient, staff, and organizational outcomes: a systematic review. European Journal of Emergency Medicine, 33(4). https://doi.org/10.1097/MEJ.0000000000001350