tient outcomes,2 11 found a positive effect on patient outcomes from higher levels of nurse staffing. The 5 studies that did not detect such an association tended to be older, and/or used smaller samples or less sophisticated methods for controlling for confounding variables. This evidence review concludes that “there is strong evidence that leaner nurse staffing is associated with increased length of stay, nosocomial infection (urinary tract infection, postoperative infection, and pneumonia), and pressure ulcers.” It concludes further that “these studies had various types and acuities of patients and, taken together, provide substantial evidence that richer nurse staffing is associated with better patient outcomes” (Seago, 2001:430).

Nursing Homes

The relationship between nurse staffing levels and patient outcomes in nursing homes has also been shown in numerous studies (Gustafson et al., 1990; Kayser-Jones et al., 1989; Nyman, 1988). Higher levels of registered nurse (RN) hours per patient have been significantly associated with patient survival, improved functional status, and discharge from the nursing home (Linn et al., 1977). Higher staff levels and lower turnover among RNs also have been found to be related to functional improvement in residents (Spector and Takada, 1991). Increased RN hours have been associated with improved mortality and the probability of discharge (Braun, 1991); with fewer pressure ulcers, catheterized residents, and urinary tract infections; and with lower rates of antibiotic use (Cherry, 1991). Higher staffing also has been related to fewer pressure sores (but more use of physical restraints) (Aaronson et al., 1994).

In addition, higher RN levels, adjusted for case mix, have been shown to be associated with lower mortality rates. An economic analysis using 1987 data from the National Medical Expenditure Survey found that an increase of 0.5 full-time equivalent (FTE) RNs per 100 residents (an approximately 10 percent increase in average RN staffing at that time) would have reduced the probability of dying by about 1 percent. Although this percentage may appear small, the researchers point out that it translates to an estimated 3,000 fewer deaths annually for nursing home residents. Moreover, a higher level of licensed practical nurse/licensed vocational nurse (LPN/LVN) staffing was found to be related to improved functional status as measured by activities of daily living (ADL) dependency (Cohen and Spector, 1996). Inadequate nurse staffing has been shown to be associated


The review included observational studies that used controls to protect against threats to validity—e.g., case control, cohort, and pre- and post-design studies and studies using data from large public databases. Observational studies without controls were excluded.

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