“We have moved from a situation where 20 years ago we had virtually nothing to now having so many studies that we can’t keep track of them,” explains Professor Peter Griffiths, chair of Health Services Research at the University of Southampton.
“The question is whether or not that is cause and effect”
Numerous studies have demonstrated a clear link between staffing levels and patient outcomes including mortality, hospital-acquired infections and length of stay.
Other research suggests having a higher ratio of nurses to nursing assistants is linked with better outcomes while the deployment of less qualified support staff is associated with worse results.
High quality research from the US on the link between nurse staffing levels and hospital mortality rates, published in 2011, and the RN4CAST study in Europe have been particularly influential.
“If you look at the body of evidence as a whole, nobody could really challenge that there is an association. The question is whether or not that is cause and effect,” said Professor Griffiths.
“There is very little to point towards what optimal levels would look like”
There are a growing number of studies that have attempted to explore the relationship between staffing and care quality more deeply and, again, the conclusion seems to be that – unsurprisingly – nurse staffing levels are directly related to key indicators such as the amount of “care left undone”, which are in turn highly likely to affect patient outcomes.
However, the picture is less clear when it comes to working out exactly how many nurses are needed to provide safe or optimal care. “That’s where it becomes much harder,” said Professor Griffiths.
“We have got a body of evidence that asks ‘How many nurses do you need?’ and it gives the answer ‘more’ in essence. There is very little to point towards what optimal levels would look like.”
Evidence is even more scant on the effectiveness safe staffing tools, he added. “If you are looking at what evidence we have for things that actually guide the decision-making about deployment on a particular ward at a particular time, the evidence is almost non-existent,” he said.
Professor Griffiths said: “There has been lots written about it and lots of studies, but actually none of it tells you whether the tools give you the right answer.”
Much of the research on safe staffing has focused on hospital care. There is less evidence in other areas including mental health, learning disability nursing, and general practice.
Perhaps the field with the next greatest volume of research is care home nursing but much of this is from the US where settings are more akin to hospitals.
When it comes to how research on nurse staffing levels has influenced policy and practice, then some might argue that the impact has been fairly minimal given ongoing shortages of registered nurses and the emphasis on developing nurse support roles like nursing associates.
However, Professor Griffiths believes it has had an impact – albeit fairly subtle – and that policy makers have taken note.
“I have a friend who is a director of nursing and she says it is incredibly useful for her to have that evidence,” he said. “It doesn’t take away the pressure to cut costs and reduce numbers but it gives her a weapon in that discussion.”
The RN4CAST study
RN4CAST studied how organisational features of hospital care impact on nurse recruitment, nurse retention and patient outcomes. In 2009-2010, the researchers surveyed fully qualified professional nurses and patients in about 500 general acute care hospitals in 12 European countries and collected discharge data from hundreds of thousands of patients. The study was funded by the European Union. Its main findings, which have been widely published since 2011, linked nurse staffing and education to patient mortality. For example, an increase in a nurses’ workload by one patient was found to increase the likelihood of an inpatient dying within 30 days of admission by 7%, and that each additional patient per nurse increased the odds of nurses reporting poor or fair quality care. Analysis of the study data is ongoing.