Literature Review: How does nursing staff ratio influence patient care outcomes?
To begin the search for articles that discuss the relationship between nurse staffing ratios and patient outcomes, the research question: “How does nursing staff ratio influence patient care outcomes?” was used in several different databases. These databases include PMC, BMJ, BMC, EBSCOhost, and Google Scholar. While this initial search returned several articles, some of them were not written about staff ratios and patient outcomes per se, but may have included a discussion about that topic. Another search was undertaken using the search term: nursing staff ratios and patient outcomes at the same databases and this yielded enough articles to complete the literature review.
Nursing staffing, the literature proves, is a controversial topic. Some assert that increasing the nurse to patient ratio is the right action to take. Others suggest that nurse to patient ratios should be considered, but also the education of the nurse (i.e., BSN or above) also affects patient outcomes. The implication here, though, is that RNs with bachelor’s degrees can work understaffed with the same outcomes as having a proper nurse to patient ratio with less well-educated nurses. This results in discussions about the best staffing methodology. Another aspect that makes the discussion of nurse to patient ratios controversial is the cost of paying the nursing labor force. Nurses are the largest group of healthcare workers and their salaries certainly account for the largest portion of the salaries and wages paid by healthcare organizations. What most of the literature concludes, however, is that there is little empirical evidence about nurse to patient staffing ratios and patient outcomes.
Patient Outcomes Vary
While it may seem like a no-brainer, it is important to point out that patient outcomes vary. Patients may experience adverse events such as falls, pressure ulcers and hospital acquired infections (HAIs) whether there is an adequate nurse to patient staff ratio or not. Aiken, et al. (2018) of Revista Médica Clínica Las Condes explains that mortality rates, for example, can be different in 2 hospitals in the same city, state or country. This may be because some hospitals have sicker patients. “The popular magazine Consumer Reports, for example, recently published an analysis of death rates in U.S. hospitals for elderly patients admitted for treatment of common acute medical conditions—pneumonia, heart failure, acute myocardial infarction—and surgery (4). Death rates for patients with these conditions were twice as high at some hospitals than for others” (Aiken, et al., 2018, p. 323). The same death rates were found in research Aiken et al. (2018) did in Europe too. It is important to keep that in mind because even absolute statements and comparisons of patient outcomes recognize the variability of experience.
Adverse Events
One of the claims made by several of the authors included in the review is that better nursing staff ratios will result in fewer adverse events (e.g., falls, pressure ulcers, being give the wrong medication, HAIs, etc.). Driscoll, et al. (2018) of the European Journal of Cardiovascular Nursing say, “Patients will also be less likely to experience an adverse event in units with a high nurse-to-patient ratio. This has important implications for clinical practice and the optimisation of patient outcome” (Driscoll, et al., 2018, p. 21). These types of general claims are made frequently in the literature; however, this assertion is not followed by a source of empirical evidence. There have been many qualitative studies done, but the results of these are useful in descriptive terms only. For example, He, Staggs, Bergquist-Beringe, and Dunton (2016) of BMC Nursing found that changes in nurse staffing were inversely associated with the rate of falls and pressure ulcers, but other factors included time of day and seasonal issues. However, they do not go so far as to claim a causal relationship. “No causal inference about staffing and patient outcomes can be made without control for improvements in quality of patient care from other aspects or changes in patient population over time, or other seasonal factors that may have influenced patient outcomes at the seasonal level” (He, Staggs, Bergquist-Beringe, & Dunton, 2016, pp. 8-9). Falls, pressure ulcers and HAIs are not the only negative patient outcomes that are thought to be affected by nursing staff ratios.
Readmissions
Aiken, et al. (2018) looked at the association between hospital nurse staffing and readmission rates. They provide some statistical data for their findings. They list several conditions for which a patient may be readmitted such as pneumonia, heart failure, and acute myocardial infarction, which showed 6%-9% inverse correlation with nurse staffing levels, hip and knee replacement readmissions showed an 8% increase, general surgery showed a 3% increase, and a huge 11% readmission rate for hospitalized children (Aiken, et al., 2018, p. 324). Aiken, et al. (2018) stop short of a causal connection though; however, they do convey that nurses report having little or no time for discharge planning or patient teaching.
Nursing Staff Levels and Mortality
The most serious problem that is laid at the feet of improper nurse staffing is patient mortality. Some of the authors cited in this literature review could apply statistics to the issue such as Driscoll, et al. (2018) says, “A higher level of nurse staffing decreased the risk of in-hospital mortality by 14%” (Driscoll, et al., 2018, p. 19). Other authors also mentioned empirical data to support their assertions about patient mortality. Paulsen (2018) of Nursing Management says, “The number of nurses available to care for patients, measured by full-time equivalents and hours per patient day (HPPD), was found to be inversely correlated with patient mortality and failure to rescue. Likewise, lower HPPD correlated with longer length of stay. And when staffing targets weren’t met, mortality increased” (Paulsen, 2018, p. 42). Other associated variables mentioned by Paulsen (2018) include higher levels of education for nurses correlating with lower rates of mortality. Neuraz, et al. (2015) of Critical Care Medicine looked at 11,666 shifts in eight ICUs over 1 year, that took into account “both staffing and workload levels, showed an increased risk of mortality . . . .The ICU risk of death increased by a factor of 3.5 when the number of patients was above 2.5 per nurse” (Neuraz, et al., 2015, p. 1590). Cho, et al. (2015) of the International Journal of Nursing Studies found even higher patient to nurse ratios in South Korea where nurses were caring for 11.4 patients on average per nurse, but Choe, et al. (2015) acknowledges that the workload varies across hospitals. These researchers then list the average patient to nurse ratios for several countries including the United States (5.7 patients per nurse on average, and conclude, “Our findings confirm that higher ratios of patients to nurses is associated with higher patient mortality rates” (Cho, et al., 2015, p. 7). While there are measurements involved, there is little agreement on how the numbers should be used to create a better outcome.
Employment Costs
The other side of the discussion is about how healthcare organizations can afford to pay as many nurses as are needed to have better nurse to patient ratios and better patient outcomes. Aiken, et al. (2018) points out that the cost of nurse staffing may be great, but the cost of HAIs are an also expensive. “The cost-savings from prevention of HAIs offset, at least in part, higher labor costs associated with the employment of more nurses” (Aiken, et al., 2018, p. 324). The difference between the two expenses is that nurse staffing occurs on a daily basis and, hopefully, HAIs not as frequently so the expense is not as great. However, the cost of a healthcare organization’s reputation is priceless.
Paulsen (2018) takes a different approach where she talks about how to determine what the right nurse staffing levels might be. Nurse managers and administrators do not know how to calculate the right balance between nurse staff and patient outcomes. Paulsen (2018) says, “Consider that in 2016, 62.2% of the country’s 2.6 million nurses worked in hospitals with a median pay of $68,450 per year. With salaries making up nearly half of U.S. hospitals’ expenses and nursing comprising about 30% of salaries, effective management of nursing resources, including staffing, is imperative for meeting financial outcomes. Likewise, managing the safety and quality of patient care is paramount, and failure to do so is expensive” (Paulsen, 2018, p. 44). Paulsen listed over $45,000 in costs for a HAI and over $14,000 for a fall, but these are inexact figures because a jury could find that the healthcare organization should pay punitive damages too especially if they were negligent in some way such as not having enough nursing staff scheduled to work.
Paulsen (2018) also points out that even though there is a strong body of knowledge about nurse staffing, it has not translated from research to unit-level practice. Hospital-level data and cross-sectional studies about costs compete with the nurse staffing data. Paulsen (2018) says, “Nurse managers, administrators, and researchers should focus efforts on developing ways to capture, access, and analyze unit-level nurse staffing and patient outcomes data” (Paulsen, 2018, p. 47). Neuraz, et al. (2015) agrees and adds support with a multicenter study that proposes the acceptable nurse staffing levels for and ICU should be 5 patients to 2 nurses. Neuraz, et al. (2015) says anything above that increases ICU mortality rates. In their study they found that weekend shifts and night shifts were the most understaffed and had the highest risk of death associated with those shifts and associated with heavy workload during those shifts (Neuraz, et al., 2015, p. 1590). Leary, et al. (2016) of BMJ Open also found a correlation between the levels of nurse staffing and negative patient outcomes. These researchers believe that it is something that can be measured objectively. “The relationship between staffing and outcomes appears to exist. It appears to be non-linear but calculable and a data-driven model appears possible. These findings could be used to build an initial mathematical model for acute staffing which could be further tested” (Leary, et al., 2016, pp. 6-7). However, at this time, there does not seem to be such a mathematical model available.
Not everybody believes that nurse staffing and negative patient outcomes are related though. Olley, Edwards, Avery, and Cooper, (2019) of the Australian Heatlh Review assert that there is limited evidence pointing to supply and demand management models of nurse staffing or staffing ratio management models that improve risk, qualithy or safety in patient care. They say,
“Intuitively, it would be reasonable to assert that if there are more nursing staff at an appropriate skill mix level, then patient care and equity in staffing levels would improve. Research undertaken in Europe demonstrates a clear relationship between skill mix and patient safety. That study also demonstrated an association between the number of patients per nurse and some measures of patient safety” (Olley, Edwards, Avery, & Cooper, 2019, p. 6). Yet, Olley, Edwards, Avery, and Cooper (2019) cannot find evidence of a nurse staffing management model that leads to improved patient outcomes.
References
Aiken, L. H., Lake, T., E., Galiano, A., Garbarini, A., Smith, H. L., . . . Bravo, D. (2018). Hospital Nurse Staffing and Patient Outcomes. Revista Médica Clínica Las Condes, 29(3), 322-327. Retrieved from http://content.ebscohost.com/C...
Cho, E., Sloane, D. M., Kim, E. Y., Kim, S., Choi, M., Yoo, I. Y., & Aiken, L. H. (2015). Effects of nurse staffing, work environments, and education on patient mortality: an observational study. International Journal of Nursing Studies, 52(2), 1-16. Retrieved from https://www.ncbi.nlm.nih.gov/p...
Driscoll, A., Grant, M. J., Carroll, D., Dalton, S., Deaton, C., Jones, I., & 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. Retrieved from https://journals.sagepub.com/d...
He, J., Staggs, V. S., Bergquist-Beringe, S., & Dunton, N. (2016). Nurse staffing and patient outcomes: a Longitudianl study on trend and seasonality. BMC Nursing, 15(60), 1-10. Retrieved from https://bmcnurs.biomedcentral....
Leary, A., Cook, R., Jones, S., Smith, J., Gough, M., Maxwell, E., & Radford, M. (2016). Mining routinely collected acute data to reveal non-linear relationships between nurse staffing levels and outcomes. BMJ Open, 6(12), 1-7. Retrieved from https://bmjopen.bmj.com/conten...
Neuraz, A., Guérin, C., Payet, C., Polazzi, S., Aubrun, F., Dailler, F., & Schott, A. M. (2015). Patient mortality is associated with staff resources and workload in the ICU: a multicenter observational study. Critical Care Medicine, 43(8), 1587-1594. Retrieved from http://massnurses.org/files/fi...
Olley, R., Edwards, I., Avery, M., & Cooper, H. (2019). Systematic review of the evidence related to mandated nurse staffing ratios in acute hospitals. Australian Heatlh Review, 43(3), 1-6. Retrieved from https://www.researchgate.net/p...
Paulsen, R. A. (2018). Taking nurse staffing research to the unit level. Nursing Management, 49(7), 42-48. Retrieved from https://www.ncbi.nlm.nih.gov/p...
