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