An Evidenced Based Approach

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January 16, 2013

Key Findings From Research Studies on Safe Nurse Staffing

(adopted from ANA’s Safe Staffing Saves Lives website)

Safe Staffing Impacts Patient Safety and Quality of Care

A study evaluating nurse staffing for every nursing shift in 43 hospital units at one hospital found that staffing of RNs below target levels was associated with increased mortality. High patient turnover -- admissions, discharges and transfers -- during a shift also was linked with greater risk of patient deaths. (See the analysis).
Evidence suggests that improving nurse work environments in hospitals could result in improved patient outcomes, including better patient experiences and higher satisfaction ratings. Patient-to-nurse ratios in hospitals do affect patient satisfaction ratings and recommendation of the hospital to others.
This systematic review and meta-analysis revealed consistent evidence that an increase in Registered Nurse (RN) to patient ratios was associated with a reduction in hospital-related mortality, failure to rescue, and other nurse-sensitive outcomes, as well as reduced length of stay. An increase in total nurse hours per patient day was associated with reduced hospital mortality, failure to rescue, and other adverse events.
Research suggests that improved registered nurse staffing has a beneficial effect on patient outcomes. Conversely, research shows that the likelihood of both overall patient mortality (i.e., in-hospital death) and mortality following a complication (failure to rescue) increases by 7% for each additional patient added to the average registered nurse workload.
Results from a sample of Pennsylvania hospitals indicates that increased nurse staffing is associated with reductions in atelectasis (lung collapse), decubitus ulcers, falls, and urinary tract infections.
Savings from shortened length of stay improve the cost-effectiveness of increased staffing, although the savings only offset half of the increased labor costs. Savings resulting from decreased length of stay would largely accrue to payers, such as health insurers, while hospitals would incur the costs of additional staffing.

Safe Staffing and Medical Errors

Hospital nurses reporting higher workloads in a survey were more likely to report more frequent medical errors and patient falls occurring in their units.
The number of hours worked by RNs is an important factor in the rate of medical errors. Odds of making an error during a shift of 12.5 hours or longer is over three times as great as during a shift of 8.5 hours or less.
The Institute of Medicine, in a study of the nursing work environment, recommends that the length of nursing shifts be limited to 12 hours in any 24 hour period, whether mandatory or voluntary.
Institute of Medicine (2004) Keeping Patients Safe: Transforming the Work Environment of Nurses. Washington, D.C., National Academies Press, p.237.

October 9, 2008

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A mounting volume of evidence clearly demonstrates the strong relationship between RN staffing and patient outcomes of care—particularly in reducing complications and death:

As early as 1988, researchers found associations between nurse staffing and development of hospital-acquired infections. (Flood & Diers 1988).
In "one of the clearest demonstrations to date of the impact of nursing staffing on outcomes for both patients and nurses in acute care hospitals," (Clarke & Aiken 2003), a study in the Journal of the American Medical Association, analyzed data from 168 Pennsylvania hospitals. After adjusting for patient and hospital characteristics, each additional patient beyond four per nurse resulted in a 7% greater likelihood of dying within 30 days of admission and a 7% increase in the likelihood of failure to rescue. (Aiken, Clarke, Sloane, Sochalski & Silber, 2001).
In a study published in the New England Journal of Medicine, data from 799 hospitals in 11 states, including 5,075,969 medical discharges and 1,104,659 surgical discharges revealed that among medical patients, a higher proportion of hours of nursing care per day provided by RNs and a greater total number of hours of nursing care per day provided by RNs were associated with a shorter length of stay, lower rates of urinary tract infections and upper gastrointestinal bleeding. A higher proportion of hours of care provided by RNs was also associated with lower rates of pneumonia, shock or cardiac arrest and failure to rescue. Among surgical patients, a higher proportion of nursing care provided by RNs was associated with lower rates of urinary tract infections. A greater number of RN hours of care per day was associated with lower rates of failure to rescue. The authors summarize their findings, in part, by noting their estimate that patients treated in whose staffing placed them in the upper quarter of hospitals studied)have lengths of stay 3-5% shorter and rates of complication 2-9% lower than those with RN staffing in the lower quarter of hospitals in the study. (Needleman, Buerhaus, Mattke, Stewart & Zelevinsky, 2002a, 2002b).
A study of 1609 hospital reports of sentinel events (unanticipated events that result in death, injury or permanent loss of function), found that 24% of such events were attributed to nurse staffing levels (Joint Commission on Accreditation of Healthcare Organizations, 2002).
Discharge data from 589 acute-care hospitals in 10 states, finding a large and significant inverse relationship between full-time equivalent RNs per adjusted inpatient day (RNAPD) and two post-surgical complications—urinary tract infections and pneumonia. (Kovner & Green, 1988).
Data from 42 units in a large university hospital found that a higher proportion of RN hours of care was associated with hospital unit rates of medication errors, pressure ulcers and patient complaints. Total nursing hours of care were associated with lower rates of pressure ulcers, patient complaints and mortality. (Blegen, Goode & Reed, 1998).
A study of 3763 U.S. hospitals found a decrease in mortality rates as staffing increased for registered nurses (Bond, Raehl, Petterle & Franke 1999).
Hospital data from New York and California showed significant relationships between RNs per adjusted patient days and incidence of urinary tract infections, pneumonia, pressure ulcers and a weaker but significant relationship to thrombosis and pulmonary complications. (Lichtig, Knauf & Milholland, 1999)
A study of 28 university hospitals that had undergone restructuring found an increase in the rate of patient falls as patient-to-nurse ratios increased. (Sovie and Jawad, 2001).
Patients undergoing abdominal aortic surgery who were cared for in ICUs with nurse:patient ratios of 1:3 or more averaged 49% greater lengths of stay in the ICU.. (Pronovost, Jenckes, Dorman, Garrett, Breslow, Rosenfeld, et al.1999).
Data for 118,940 patients hospitalized with acute myocardial infarction showed lower likelihood of in-hospital mortality for patients treated in hospitals with higher RN staffing levels. (Person, Allison, Kiefe, Weaver, Williams, Centor, et al., 2004).
Data from hospitals in states participating in the National Inpatient Sample (NIS) maintained by the federal Agency for Healthcare Research and Quality showed that higher levels of nurse staffing were associated with lower rates of pneumonia. (Kovner, Jones, Zhan, Gergen & Basu (2002).
An increase of 1 hour of RN care per patient day in California hospitals was associated with an 8.9% decrease in the odds of pneumonia. A 10% increase in proportion of RNs was associated with a 9.5% decrease in the odds of pneumonia. (Cho, Ketefian, Barkauskas & Smith 2003).
Rates of bloodstream infections related to central venous catheter use in eight intensive care units were significantly associated with the use of “float” nurses (Alonso-Echanove, Edwards, Richards, Brennan, Venezia, Keen, et al., 2003).
Data from 1751 units in hospitals participating in the National Database of Nursing Quality Indicators found that higher rates of patient falls were associated both with fewer nursing hours per patient day and a lower percentage of RNs. (Dunton, Gajewski, Taunton & Moore, 2004).
In a study of 19 teaching hospitals in Ontario, Canada, a lower proportion of RNs employed on a hospital nursing unit was associated with higher numbers of medication errors and wound infections. (McGillis Hall, Doran & Pink 2004).
A nurse-patient ratio of 1:2 was associated with a higher incidence of unplanned extubation relative to a nurse-to-patient ratio of 1:1. (Marcin, Rutan, Rapetti, Brown, Rahnamayi & Pretzlaff).
Analyzing data from two large hospital studies compared nurse staffing levels ranging from four to eight patients per nurse, mortality among medical and surgical patients decreased as staffing increased. (Rothberg, Abraham, Lindenauer & Rose, 2005).

Nurse staffing decisions need to be based on the wide range of factors that have an impact on patient outcomes, including overall numbers and proportions of RNs:

Other important factors that have been examined include level of education (Aiken, Clarke, Cheung, Sloane & Silber, 2003; Estabrooks, Midodzi, Cummings, Ricker & Giovanetti, 2005) and experience level (Tourangeau, Giovanetti, Tu & Wood, 2002; Blegen, Vaughn & Goode 2001).
Additional research has pointed to the association between the use of “float” nurses (nurses assigned to units outside of their usual specialty areas) and greater incidence of bloodstream infections among intensive care unit (ICU) patients with central venous catheters (Alonso-Echanove, Edwards, Richards, Brennan, Venezia, Keen, et al., 2003).
An analysis of outcomes data for 18,142 patients discharged from 49 acute care hospitals in Alberta, Canada, found an association between higher proportion of casual or temporary (such as agency) nurses and 30-day mortality rates (Estabrooks, Midodzi, Cummings, Ricker & Giovanetti, 2005).

Enhancing nurse staffing does not pose a significant cost for hospitals and in fact may result in cost savings:

Lichtig, Knauf & Milholland (1999) suggested that by decreasing adverse outcomes (particularly those that are likely to result in increased length of stay), increased RN staffing could result in modestly decreased hospital costs.
Earlier, Flood & Diers (1988) had similarly suggested an association between staffing levels and lower hospital costs resulting from decreased rates of nosocomial infections.
Most recently, Needleman and his colleagues (2006) examined the data used in their 2002 study (discussed earlier) in order to determine the impact on hospital costs of different adjustments in nurse staffing. Under different potential staffing scenarios, they found that increasing overall hours of nursing care (irrespective of overall skill mix) would lead to a significant reduction in length of stay, patient deaths and other adverse outcomes, at net increase of hospital costs of 1.5% percent or less. Increasing RN hours as a proportion of nursing hours without increasing overall nursing hours (i.e., increasing skill mix while holding nurse staffing hours steady) was associated with a small net reduction in costs.
A study of patient mortality and length of stay data from two large hospital studies compared staffing ratios ranging from 8:1 to 4:1 and noted the cost-effectiveness of increased nurse staffing (Rothberg, Abraham, Lindenauer & Rose, 2005).