Fewer registered nurses linked to increased mortality risk in wards

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NursesAdmission to a hospital ward with below average numbers of fully trained (registered) nurses to care for patients is linked to a 3% rise in the risk of death for each day the shortfall persists, suggests UK research. But plugging the gap with unregistered nursing assistants isn’t associated with any diminution in patient harm, suggesting that while these healthcare workers have a key role in maintaining ward safety, “they cannot act as substitutes for (registered nurses),” say the researchers at  the University of Southampton, Karolinska Institutet, Stockholm, Sweden, Libera Universita Maria Santissima Assunta, Roma, Italy, University of Portsmouth, University of Oxford Nuffield department of clinical neurosciences, Portsmouth Hospitals NHS Trust, University of Bournemouth and the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care.

The proportion of fully trained registered nurses on hospital wards in the UK is among the lowest in Europe. And many hospitals now rely on unregistered nursing assistants to provide a substantial amount of hands-on care, say the researchers.

To find out what impact this skill mix might be having on patient safety in hospital wards, the researchers drew on routinely collected data for staffing levels for all adults admitted to 32 wards in one large acute care hospital trust in the South of England between April 2012 and March 2015.

During this period, 138,133 adults spent at least one day on general medical and surgical wards, and most (79%) were admitted as emergencies. Their average age was 67; 14% were aged 85 and older. Staffing levels were measured as hours per patient per day. But across all the wards, staffing levels for registered nurses averaged 4.75 hours, while those for nursing assistants averaged 2.99.

Over the first five days of their stay, patients experienced, on average, nearly 2 days of low (below average) registered nurse and nursing assistant staffing levels, adding up to a cumulative shortfall of 23 and 15 minutes, respectively, each.

During the study period, the overall death rate was just over 4% (5662 deaths). Analysis of the data showed that the odds of dying rose by 3% for each day that a patient spent with registered nurse staffing levels below the average for that ward.

Although low nursing assistant staffing levels were also associated with a heightened risk of death (4%), so too were above average staffing levels. Days where the number of admissions for each registered nurse was substantially higher than usual-more than 25% above average-were associated with a 5% heightened risk of death.

Each additional hour of care provided by a registered nurse was associated with a 3% reduction in the chances of dying, the analysis showed. But no such impact was observed for additional hours of care provided by nursing assistants.

Based on their data, the researchers suggest that providing one additional hour of registered nurse care would be the equivalent of one extra nurse on each shift for a 24-bed ward.

This is an observational study, and as such, can’t establish cause, emphasise the researchers. But the findings are broadly in line with those of other previously published studies, they say.

And although the study involved only one hospital site, so may not be typical, the researchers point out that this avoids the observed associations being influenced by the “hospital effect,” whereby hospitals with more resources employ more nurses.

“The findings of this paper suggest potential benefits from increasing the availability of (registered nurses) on acute hospital wards,” write the researchers.

“However, in England, RN shortages look set to continue in the short term… (These) are unlikely to be remedied by increasing the numbers of lesser trained nursing staff in the workforce,” they add.

Abstract
Objective: To determine the association between daily levels of registered nurse (RN) and nursing assistant staffing and hospital mortality.
Design: This is a retrospective longitudinal observational study using routinely collected data. We used multilevel/hierarchical mixed-effects regression models to explore the association between patient outcomes and daily variation in RN and nursing assistant staffing, measured as hours per patient per day relative to ward mean. Analyses were controlled for ward and patient risk.
Participants: 138 133 adult patients spending >1 days on general wards between 1 April 2012 and 31 March 2015.
Outcomes: In-hospital deaths.
Results: Hospital mortality was 4.1%. The hazard of death was increased by 3% for every day a patient experienced RN staffing below ward mean (adjusted HR (aHR) 1.03, 95% CI 1.01 to 1.05). Relative to ward mean, each additional hour of RN care available over the first 5 days of a patient’s stay was associated with 3% reduction in the hazard of death (aHR 0.97, 95% CI 0.94 to 1.0). Days where admissions per RN exceeded 125% of the ward mean were associated with an increased hazard of death (aHR 1.05, 95% CI 1.01 1.09). Although low nursing assistant staffing was associated with increases in mortality, high nursing assistant staffing was also associated with increased mortality.
Conclusion: Lower RN staffing and higher levels of admissions per RN are associated with increased risk of death during an admission to hospital. These findings highlight the possible consequences of reduced nurse staffing and do not give support to policies that encourage the use of nursing assistants to compensate for shortages of RNs.
This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made.

Authors
Peter Griffiths, Antonello Maruotti, Alejandra Recio Saucedo, Oliver C Redfern, Jane E Ball, Jim Briggs, Chiara Dall’Ora, Paul E Schmidt, Gary B Smith

BMJ material
Journal of Epidemiology and Community Health abstract


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