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What’s New in the Patient Safety World

June 2021

Does Nurse-to-Patient Ratio Legislation Help?



We’ve done multiple columns discussing how better nursing staffing leads to better patient outcomes and improved patient safety. We’ve stressed the importance of nurse workload rather than staffing levels per se. But most attempts to improve nurse staffing have focused on nurse-to-patient ratios. What is the evidence that just mandating a minimum nurse-to-patient ratio improves outcomes? One of the problems is that all prior studies have been before-and-after evaluations and none were prospective.


A recent study from Queensland, Australia appears to answer that. McHugh et al. (McHugh 2021) were able to prospectively compare patient outcomes at 27 hospitals subject to minimum nurse-to-patient ratios (the “intervention” hospitals) with 28 hospitals that were not (the “comparison” hospitals).


After implementation, mortality rates were not significantly higher than at baseline in comparison hospitals (adjusted odds ratio 1.07) but were significantly lower than at baseline in intervention hospitals (aOR 0.89). From baseline to post-implementation, readmissions increased in comparison hospitals (1.06), but not in intervention hospitals (1.00). Length of stay (LOS) decreased in both groups post-implementation, but the reduction was more pronounced in intervention hospitals than in comparison hospitals. Staffing improvements by one patient per nurse produced reductions in mortality (OR 0.93), readmissions (0.93), and LOS (adjusted incident rate ratio 0.97).


And here’s the key point for administrators and policy makers: in addition to producing better outcomes, the costs avoided due to fewer readmissions and shorter LOS were more than twice the cost of the additional nurse staffing. We always add a point of caution when using formulas to impute cost savings from fewer admissions and shortened length of stay – those savings would come from actually reducing personnel costs. Those hospitals that can benefit the most from such reductions are those that can close a whole nursing unit. Lesser reductions are more difficult to achieve. We also reiterate our position that some flexibility is needed. Rather than just focusing on the nurse-to-patient ratio, we need to match nurse workload to patient load. But improving the nurse-to-patient ratio is a good first step.


We hope that the naysayers to mandated minimum nurse-to-patient ratios who say such mandates would be too costly will look at the results from Queensland and reassess their opposition to such mandates.


As pointed out in the editorial accompanying the McHugh study (Ullman 2021), the current and likely near-future shortage of nurses makes improving nurse-to-patient ratios challenging. Ullman calls for robust efforts to boost the nursing workforce.



Some of our other columns on nursing workload and missed nursing care/care left undone:


November 26, 2013    Missed Care: New Opportunities?

May 9, 2017                Missed Nursing Care and Mortality Risk

March 6, 2018             Nurse Workload and Mortality

May 29, 2018              More on Nursing Workload and Patient Safety

October 2018               Nurse Staffing Legislative Efforts

February 2019             Nurse Staffing, Workload, Missed Care, Mortality

July 2019                    HAI’s and Nurse Staffing

September 1, 2020      NY State and Nurse Staffing Issues

February 9, 2021         Nursing Burnout






McHugh MD, Aiken LH, Sloane DM, et al. 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 2021; Published: May 11, 2021



Ullman AJ, Davidson PM. Patient safety: the value of the nurse. The Lancet 2021; Published: May 11, 2021





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