The Relationship of Nursing Workforce Characteristics to Patient Outcomes

Nancy Dunton, PhD; Byron Gajewski, PhD; Susan Klaus, PhD, RN; Belinda Pierson, MA

Disclosures

Online J Issues Nurs. 2007;12(3) 

In This Article

A Study to Assess the Economic Value of Nursing Staff and RNs

A recent study was conducted using NDNQI data to assess the value of nurses in terms of averting patient falls and hospital-acquired pressure ulcers. The analysis file, the analytic approach, and the findings of this study will be described and discussed below. This study was the first NDNQI study to include the workforce characteristic of RN experience. All data were collected under protocols approved by the University of Kansas Medical Center's institutional review board.

Annualized measures were calculated from the quarterly data for the period from July 1, 2005, through June 30, 2006. RN characteristics from the RN survey were matched to quarterly data on staffing and outcomes on the basis of the quarter in which the survey month occurred. The hospital unit was the unit of analysis and included 1,610 critical care, step down, medical, surgical, combined medical-surgical, and rehabilitation units.

The analysis proceeded in two phases. First, an exploratory analysis using regression trees examined the relationship between several nursing workforce characteristics and the adverse events of patient falls and hospital-acquired pressure ulcers (HAPUs). The models included five hospital characteristics (staffed bed size, teaching status, metropolitan location, Magnet status, and ownership), six unit types, and 20 nursing workforce attributes. Regression trees sequentially identified independent variables most highly related to the dependent variable, in this case the fall rate or HAPU rate. The regression trees were used to narrow the number of indicators to be included in the formal modeling, comprising the second phase of the analysis. The formal modeling was conducted using mixed linear models, which are hierarchical and account for the dependencies among units within the same hospital. Each patient outcome was related to three hospital characteristics, six unit types, and eight nursing workforce characteristics ( Table 2 ).

The results indicated that lower fall rates were related to higher total nursing hours (including RN, LPN/LVN, and unlicensed nursing assistants) per patient day, a higher percentage of nursing hours supplied by RNs, and a higher percentage of nurses on a unit with more than 10 years experience in nursing.

  • For every increase of one hour in total nursing hours per patient day, fall rates were 1.9% lower.

  • For every increase of 1 percentage point in the percent of nursing hours supplied by RNs, the fall rate was 0.7% lower.

  • For every increase of a year in average RN experience, the fall rate was 1% lower.

  • Fall rates were highest on rehabilitation units and lowest on critical care units.

  • Fall rates in Magnet facilities were 10.3% lower than rates in non-Magnet facilities.

To promote the lowest fall rates, nurse managers could simultaneously optimize total nursing hours and both percentage of hours supplied by RNs and RNs with longer experience in nursing. For example, by increasing nursing hours from 6 to 7 hours per patient day, increasing the percentage of hours supplied by RNs from 60% to 70%, and increasing the average experience of RNs by 5 years, the fall rate would, on average, be reduced by 7.7%.

Lower HAPU rates were related to fewer total nursing hours per patient day, a higher percentage of hours supplied by RNs, and a higher percentage of RNs with 10 or more years of experience in nursing.

  • For every increase of 1 hour in total nursing hours per patient day, HAPU rates were 4.4% higher. Although the analysis controlled for unit type, which is accepted as a proxy for patient acuity, this anomalous result may indicate inadequate risk adjustment or acuity adjustment. That is, net of hospital size, teaching status, Magnet status, and unit type, units with sicker patients at risk of pressure ulcers may have higher levels of nurse staffing.

  • For every percentage point increase in the percentage of nursing hours supplied by RNs, HAPU rates were 0.7% lower.

  • For every increase of a year in average RN experience, the HAPU rate was 1.9% lower.

  • HAPU rates are highest on critical care units and lowest on the combined floor units, i.e. step down, medical, surgical, and combined medical-surgical units.

Nurse managers could promote the lowest HAPU rates if they would simultaneously increase the percentage of hours supplied by RNs from 60% to 70% and increase the average experience of RNs by 5 years. If managers arranged the staffing in this way, the HAPU rate could be reduced by an average of 11.4%.

The findings from this study are limited in two ways. First, the results are generalizeable only to NDNQI facilities, which are self-selected for their interest in nursing quality indicators and their ability to participate in a national database. These facilities are larger, less likely to be for-profit, and more likely to be Magnet facilities than all hospitals in the AHA database. Second, the anomalous relationship between total nursing hours per patient day and HAPU rates suggests that more specific controls for patient acuity or risk should be included in the formal models.

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