NUR 602 Module 3 Manuscript: Integrated Review of Nurse Staffing and Hospital Mortality Example

Registered Nurse Staffing and Hospital Mortality: An Integrated Review of Evidence From 2016 to 2023

Student Name

Edson College of Nursing and Health Innovation, Arizona State University

NUR 602: State of the Science in Nursing and Healthcare Innovation

Instructor Name

Month Day, Year

Registered Nurse Staffing and Hospital Mortality: An Integrated Review of Evidence From 2016 to 2023

Abstract

Background: Hospital nurse staffing is debated in legislatures and boardrooms, yet decisions often rest on older, cross-sectional evidence. Aim: To synthesize recent evidence on registered nurse staffing and hospital mortality. Method: Integrated review of studies published 2016 to 2023, identified through PubMed and CINAHL using subject headings and keywords and screened against predefined criteria. Results: Ten studies met the criteria: two reviews, a meta-analysis, two cross-sectional studies, four longitudinal studies and a prospective policy evaluation, with one combining observation and projection. In every study, richer registered nurse staffing went with lower mortality. Longitudinal studies measuring patient-level exposure strengthened causal inference, assistant staff did not substitute for registered nurses and missed care emerged as a likely mechanism. Conclusions: The association is consistent and increasingly supported by stronger designs. Evidence from rural and small hospitals is absent.

Introduction

Registered nurses are the clinicians most continuously present at the hospital bedside, and how many patients share one nurse determines how closely each is watched. Earlier research established an association between staffing and mortality, largely through cross-sectional comparisons of hospitals, which left open whether better-staffed hospitals simply differed in other ways. Since 2016, three developments have changed the evidence base: national guidance on safe staffing in the United Kingdom prompted a structured review of the evidence (Griffiths et al., 2016), researchers began linking patient-level records to daily or shift-level staffing data, and Australian ratio legislation created a natural experiment (McHugh et al., 2021). In the United States, proposals for minimum staffing standards continue to be debated at state level (Lasater et al., 2021). The review therefore asks whether adults in acute care hospitals die less often where registered nurse staffing is higher, and how strongly the evidence supports cause.

Method

Design: An integrated review, chosen to combine reviews, cross-sectional, longitudinal and policy studies in one synthesis.

Search: two databases, PubMed and CINAHL, plus a look at the Cochrane Library, using three concepts combined with AND: staffing (subject heading for personnel staffing and scheduling, plus nurse staffing, nurse-to-patient ratio, patient-to-nurse ratio, nursing workload and skill mix), registered nurses (subject heading for hospital nursing staff, plus registered nurse) and mortality (subject heading for hospital mortality, plus mortality and failure to rescue).

Criteria: Included were original quantitative studies or systematic reviews in adult acute care hospitals, published in English in peer-reviewed journals from 2016 to 2023, with a measure of registered nurse staffing and mortality as an outcome. Excluded were long-term care and community settings, commentaries and studies without a quantitative staffing measure.

Screening and extraction: Titles and abstracts were screened against the criteria, followed by full-text review. Each included study was abstracted into the eight-column evidence table described in Table 1.

Appraisal: Each study was appraised for design strength, measurement of staffing and control of confounding.

Results

Overview

Ten studies met the criteria (Table 1). They covered hospitals in England, continental Europe, Switzerland, Australia and Illinois, and they expressed staffing in four ways: patient load, nursing hours against a ward norm, the share of professional nurses and the gap from target on each shift.

Cross-Sectional Evidence

Two multinational cross-sectional studies found that a thinner share of degree-level nurses among nursing staff (Aiken et al., 2017) and higher patient loads (Ball et al., 2018) were associated with higher mortality. These studies are large but cannot rule out differences between hospitals as an explanation.

Longitudinal Evidence

Four longitudinal studies measured each patient's exposure to staffing over time. In one English trust, every day spent on a ward staffed below its usual registered nurse level added to a patient's risk of dying (Griffiths et al., 2019). Shift-by-shift data from a Swiss university hospital pointed the same way, with understaffed shifts tied to more deaths (Musy et al., 2021), and an analysis spanning English trusts linked more registered nurses per patient with fewer inpatient deaths (Zaranko et al., 2023). A systematic review restricted to longitudinal designs reached the same conclusion (Dall'Ora et al., 2022). Because these designs compare patients within the same hospitals, they reduce the confounding that weakens cross-sectional studies.

Mechanisms and Substitution

Two findings suggest how staffing affects mortality. Missed care, nursing tasks left undone, was associated with both higher patient loads and higher mortality, pointing to surveillance and care omissions as a pathway (Ball et al., 2018). Increases in assistant staff did not offset low registered nurse staffing (Griffiths et al., 2019), consistent with the finding that a lower professional nurse share is associated with higher mortality (Aiken et al., 2017).

Specialist Units

Pooling studies from intensive care, cardiac and other specialist units, a meta-analysis showed that units with fewer patients per nurse had lower death rates and fewer complications (Driscoll et al., 2018).

Policy Evidence

After Queensland mandated minimum ratios, staffing improved, and mortality and readmissions fell relative to comparison hospitals, with shorter stays (McHugh et al., 2021). An Illinois analysis estimated that a 4:1 staffing standard on medical-surgical units would be associated with fewer deaths and cost savings (Lasater et al., 2021).

Discussion

Across 2016 to 2023 the direction never varies: better registered nurse staffing, lower mortality. What has changed is the strength of the designs. Longitudinal studies that link each patient's exposure to staffing on the days or shifts they were in hospital address the main weakness of earlier work, that well-staffed hospitals might differ in unmeasured ways. When the same hospitals show higher mortality on understaffed days, hospital-level confounding becomes a less plausible explanation, although day-to-day differences in patient acuity could still contribute (Dall'Ora et al., 2022).

The policy evaluation from Queensland adds a different kind of evidence. Legislation changed staffing for reasons unrelated to individual patients, approximating an experiment, and outcomes improved relative to comparison hospitals (McHugh et al., 2021). Together with the longitudinal studies, it moves the field closer to a causal claim than cross-sectional evidence alone could.

Two findings matter for workforce decisions. First, assistant staff do not appear to substitute for registered nurses in protecting patients from death (Aiken et al., 2017; Griffiths et al., 2019). Skill-mix changes that replace registered nurses to save costs may therefore carry risk. Second, missed care offers a plausible mechanism: when nurses are stretched, surveillance and timely response suffer (Ball et al., 2018), linking staffing research to the literature on recognizing deterioration.

The evidence has limits. Staffing measures differ across studies, preventing a single pooled effect and making it hard to define a safe threshold, a limitation the national guidance review identified (Griffiths et al., 2016). Most studies come from large hospitals in England, Europe and Australia. None examined rural or small hospitals, where staffing may involve one or two registered nurses on a night shift and where escalation depends on providers off site. U.S. evidence in this period is largely confined to policy projections.

Implications for research follow from these gaps. Studies are needed in rural and critical access hospitals, using measures that capture very small staffing numbers, and studies that test mechanisms such as missed surveillance directly. Implications for practice and policy are already clear enough to act on: staffing decisions should treat registered nurse hours as a patient safety measure, not only a cost.

Conclusion

Recent evidence strengthens the case that registered nurse staffing affects hospital mortality. The next step for the science is to extend it to the hospitals it has so far left out.

References

Aiken, L. H., Sloane, D., Griffiths, P., Rafferty, A. M., Bruyneel, L., McHugh, M., Maier, C. B., Moreno-Casbas, T., Ball, J. E., Ausserhofer, D., & Sermeus, W. (2017). Nursing skill mix in European hospitals: Cross-sectional study of the association with mortality, patient ratings, and quality of care. BMJ Quality & Safety, 26(7), 559-568. https://doi.org/10.1136/bmjqs-2016-005567

Ball, J. E., Bruyneel, L., Aiken, L. H., Sermeus, W., Sloane, D. M., Rafferty, A. M., Lindqvist, R., Tishelman, C., & Griffiths, P. (2018). Post-operative mortality, missed care and nurse staffing in nine countries: A cross-sectional study. International Journal of Nursing Studies, 78, 10-15. https://doi.org/10.1016/j.ijnurstu.2017.08.004

Dall'Ora, C., Saville, C., Rubbo, B., Turner, L., Jones, J., & Griffiths, P. (2022). Nurse staffing levels and patient outcomes: A systematic review of longitudinal studies. International Journal of Nursing Studies, 134, Article 104311. https://doi.org/10.1016/j.ijnurstu.2022.104311

Driscoll, A., Grant, M. J., Carroll, D., Dalton, S., Deaton, C., Jones, I., Lehwaldt, D., McKee, G., Munyombwe, T., & Astin, F. (2018). The effect of nurse-to-patient ratios on nurse-sensitive patient outcomes in acute specialist units: A systematic review and meta-analysis. European Journal of Cardiovascular Nursing, 17(1), 6-22. https://doi.org/10.1177/1474515117721561

Griffiths, P., Ball, J., Drennan, J., Dall'Ora, C., Jones, J., Maruotti, A., Pope, C., Recio Saucedo, A., & Simon, M. (2016). Nurse staffing and patient outcomes: Strengths and limitations of the evidence to inform policy and practice. A review and discussion paper based on evidence reviewed for the National Institute for Health and Care Excellence Safe Staffing guideline development. International Journal of Nursing Studies, 63, 213-225. https://doi.org/10.1016/j.ijnurstu.2016.03.012

Griffiths, P., Maruotti, A., Recio Saucedo, A., Redfern, O. C., Ball, J. E., Briggs, J., Dall'Ora, C., Schmidt, P. E., & Smith, G. B. (2019). Nurse staffing, nursing assistants and hospital mortality: Retrospective longitudinal cohort study. BMJ Quality & Safety, 28(8), 609-617. https://doi.org/10.1136/bmjqs-2018-008043

Lasater, K. B., Aiken, L. H., Sloane, D., French, R., Martin, B., Alexander, M., & McHugh, M. D. (2021). Patient outcomes and cost savings associated with hospital safe nurse staffing legislation: An observational study. BMJ Open, 11(12), Article e052899. https://doi.org/10.1136/bmjopen-2021-052899

McHugh, M. D., Aiken, L. H., Sloane, D. M., Windsor, C., Douglas, C., & Yates, P. (2021). Effects of nurse-to-patient ratio legislation on nurse staffing and patient mortality, readmissions, and length of stay: A prospective study in a panel of hospitals. The Lancet, 397(10288), 1905-1913. https://doi.org/10.1016/S0140-6736(21)00768-6

Musy, S. N., Endrich, O., Leichtle, A. B., Griffiths, P., Nakas, C. T., & Simon, M. (2021). The association between nurse staffing and inpatient mortality: A shift-level retrospective longitudinal study. International Journal of Nursing Studies, 120, Article 103950. https://doi.org/10.1016/j.ijnurstu.2021.103950

Zaranko, B., Sanford, N. J., Kelly, E., Rafferty, A. M., Bird, J., Mercuri, L., Sigsworth, J., Wells, M., & Propper, C. (2023). Nurse staffing and inpatient mortality in the English National Health Service: A retrospective longitudinal study. BMJ Quality & Safety, 32(5), 254-263. https://doi.org/10.1136/bmjqs-2022-015291