Nurse Staffing and Patient Outcomes:
Examining the Evidence in Acute Care and Nursing Homes
December 2006 (download pdf file)

I. Introduction | II. Acute Care Settings | III. Nursing Homes

IV. Conclusion | V. References

III. Nursing Homes

Appropriateness of Minimum Nurse Staffing Ratios in Nursing Homes

The Centers for Medicare & Medicaid Services (CMS) mandates certain nurse staffing requirements under the statutory authority of The Omnibus Budget Reconciliation Act of 1987 (OBRA '87). The general requirement is that nursing homes must provide “...sufficient nursing staff to attain or maintain the highest practicable ... well-being of each resident...” Many healthcare professionals argue this requirement, when implemented in practice, is too vague to serve as an adequate Federal standard. There are also specific minimum requirements of 8-hours of registered nurse and 24-hours of licensed nurse coverage per day. However, since this minimum is the same for all facilities (e.g., the same minimum standard for a 60 bed facility or a 600 bed facility), many professionals also agree this requirement as inadequate; they argue for a required minimum nurse staffing to resident ratio.

The evidence concerning nurse staffing and quality in nursing homes is minimal when compared to that found examining nurse staffing and quality outcomes in acute care settings. However correlational studies have revealed associations between nurse staffing (particularly RNs) and a number of resident outcomes. The types of outcomes examined include lower death rates, higher rates of discharges to home, improved functional outcomes; fewer pressure ulcers, fewer urinary tract infections, lower urinary catheter use, and less antibiotic use. 60-68

Inadequate nurse staffing has been associated with inadequate feeding assistance during meals, poor skin care, lower activity participation, and less toileting assistance. 67,69-71 The results of these correlational studies led two Institute of Medicine committees to recommend higher nurse staffing in nursing facilities, including 24-hour registered nursing care. 72,73

Institute of Medicine

In 1996, the IOM report “Nursing Staff in Hospitals and Nursing Homes: Is it Adequate?”73 concluded:

The preponderance of evidence, from a number of studies, using different types of quality measures, shows a positive relationship between nursing staff levels and quality of nursing home care, which in turn, indicates a strong need to increase the overall level of nursing staff in nursing homes. (p.153) 73

The report, however, did not recommend appropriate levels of nursing staff, identifying that the research literature did not define an optimal staffing level, nor how to account for varying circumstances among nursing homes, including differences in the types of care needed by individual facilities’ residents (also referred to as “case-mix”). 73

The 2000 IOM report “Improving the Quality of Long Term Care” 74, reiterated

The research evidence suggests that both nursing-to-resident staffing levels and the ratio of professional nurses to other nursing personnel are important predictors of high quality of care in nursing homes. The research literature, however, does not answer the question of what particular skill mix is optimal. 73 Nor does it take into account possible substitutions for nursing staff and ways to best organize all staff. Moreover, nurse staffing levels alone are a necessary, but not a sufficient, condition for positively affecting care in nursing homes. Training, supervision, environmental conditions, leadership and management, and organizational culture (or capacity) are essential elements in the provision of quality care to residents. Overall, there is a need for sufficient, well-trained, and motivated staff to provide consumer-centered care in nursing homes, as required in OBRA 87. (p.190) 74

Few studies have specifically examined the association between staffing and the implementation of daily care processes and none of the correlational studies including the CMS study directly measured specific care processes that may be better implemented in higher staffed homes and could explain the effects on resident outcomes.

Centers for Medicare & Medicaid Services

The most notable study done to date, by the Centers for Medicare & Medicaid Services (CMS) published in 2001 68, titled “Appropriateness if Minimum Nurse Staffing Ratios in Nursing Homes” examined relationships between nurse staffing and a number of resident outcomes during its two phase study.

Phase I

Phase I established that there are critical ratios of nurses to residents below which nursing home residents are significantly at risk of quality problems. These critical ratios exist for certified nurse aides, total licensed staff, and registered nurses. This conclusion was based on analyses that were specifically designed to identify critical nurse staffing ratio thresholds, evidence that was not provided in other analyses, including the Institute of Medicine’s (IOM) studies published in 1996 73 and 2001. 72 The 2001 IOM report called for the federal government to develop minimum staffing levels (that specify number and skill mix) for direct care that are based on case mix-adjusted standards. To develop these standards, the IOM recommended that the U.S. Department of Health and Human Services fund research to examine the actual time and staff mix required to provide adequate processes and outcomes of care consistent with the needs and variability of consumers in these settings.

CMS Phase I analyses indicated that to meet the staffing thresholds, staffing levels would have to be increased in a substantial portion of facilities. However, a major limitation of this study was that the minimum staffing levels required were projected only for an average nursing home. Many nursing homes are not average in the sense that facilities vary widely in terms of the residents they serve and the care requirements of these residents. Thus, study limitations indicate the specific thresholds identified in Phase I were tentative.

Phase II

The purpose of the CMS Phase II study 68 was to replicate the prior analyses with more recent and better quality data, and a larger, more nationally representative sample of nursing homes.

The Phase II study 68 examined associations between nursing staffing and quality of care at more than 5,000 nursing facilities in 10 states. The data revealed that among long-term residents, nurse staffing levels below 4.1 hours per resident day (below 1.3 hours per resident day for licensed nurses (RNs, LPNs) and below 2.8 hours per resident day for nurse aides and assistants could have adverse consequences such as pressure sores and urinary incontinence. 75 Thus, there appears to be evidence supporting the relationship between increases in nurse staffing ratios and avoidance of critical quality of care problems. Above identified nurse staffing thresholds, however, increased staffing did not result in improved quality. Depending on the nursing home population, the thresholds ranged between 2.4 - 2.8, 1.15 - 1.30, and 0.55 - 0.75 hours/ resident day for nurse aides, licensed staff (RNs and LPNs combined), and Registered Nurses, respectively. Although no significant quality improvements were observed for staffing levels above these thresholds, quality was improved with incremental increases in staffing up to and including these thresholds.