The final sample for this analysis included 47 hospitals from 11 geographical areas. Sixty percent of the hospitals in this study were located in areas designated as having a nurse shortage, an almost identical proportion to that of states with shortages (29 of 50) (U.S. DHHS 2002). The average size of these hospitals was 320 staffed acute care beds (range 104–870). The number of participating units from the hospitals varied from three to nine. The majority of the hospitals, 38, were private nonprofit institutions; five were local or state government owned, and four were for-profit hospitals. The hospitals were located in urban or suburban areas. The Federal Medicare case-mix index averaged 1.49 (range 1.18–2.01). Of the 47 hospitals, 17 had eight or more of the technologies and procedures about which we inquired, 27 had four to seven, and four had three or fewer. The most common types of technology were CT scanner, MRI, and diagnostic radio-isotopes.
More than half (51 percent) of participating hospitals employed medical residents, while only 15 percent of them were members of the Council of Teaching Hospitals. Teaching intensity (ratio of residents to hospital beds) ranged between 0.00 and 1.7 (median for all hospitals = 0.00, median for the 23 hospitals with residents = 0.09). One of the highly complex hospitals used a large number of residents (the 1.7 ratio) although was not an affiliate with the University Hospital Consortium on which we based our exclusion of academic health centers. Analyses were completed with and without that hospital and there were no differences in direction or significance of the results. The characteristics of the patients treated by these hospitals varied. The proportion of hospital patients with private health insurance or Medicare ranged between 44 and 96 percent with an average of 78 percent. On average, 61 percent of their patients were female. The proportion of patients from non-Caucasian backgrounds varied between 1 and 62 percent, with an average of 33 percent.
Hospitals provided data for 150 medical/surgical units, 51 stepdown/telemetry units, and 78 ICUs. Medical/surgical units had an average of 34 beds, stepdown/telemetry units had an average of 32 beds and ICUs had an average of 15 beds. The nurse staffing levels varied greatly across unit types (see ). Total Hppd averaged 16.20 hours in ICU; 8.34 in stepdown units, and 7.17 in medical/surgical units. RN Hppd averaged 14.86 in intensive care, 5.64 in stepdown, and 4.49 in medical/surgical units. The average RN mix values were 92 percent in intensive care, 68 percent in stepdown, and 63 percent in medical/surgical units. The average licensed mix was 93 percent in intensive care, 71 percent in stepdown, and 68 percent in medical/surgical units. More hours of care are attributed to overtime (5.8 percent) than to agency/traveler sources (1.9 percent). Medical/surgical units used fewer agency/traveler hours and overtime hours than other types of units, although these differences were not statistically significant. Vacancy and turnover rates did not differ across types of units.
Nurse Staffing by Type of Unit
presents the specific hospital characteristics and the nurse staffing levels for each of the four complexity groupings (1—low, 4—high). Unit-level staffing data are presented separately for nonintensive care and ICUs. While the hospital characteristic averages increased across the four levels of complexity, the patterns for each of the four characteristics were distinct. The four highest complexity hospitals were distinguished from the other hospitals by three variables, bed size, technology, and teaching status (ratio of residents to beds), while they shared a similar level of patient acuity (case-mix index) with hospitals in complexity level 3. Hospitals in complexity level 1 were distinct from the others in their low-technology level and shared with hospitals in complexity level 2 a low case-mix index.
Hospital Characteristics and Unit-Level Nurse Staffing by Hospital Complexity
Non-ICU staffing varied systematically across the complexity groupings, with hospitals in complexity level 4 having higher total hours per day, higher RN hours per day, and higher RN staff mix. Hospitals in the lowest complexity group had the lowest proportion of licensed nurses (RNs and LPNs). ICU nurse staffing levels did not differ across the four complexity groupings. Intensive care staffing has been set by national professional groups and varies less across hospitals than staffing in other types of units.
Staffing levels and the relationships among staffing and other variables differ between non-ICUs and ICUs. Therefore, bivariate correlations were done using two subsets of units. contains the correlations for non-ICUs and contains the correlations for ICUs (coefficients discussed here are all statistically significant at p<.05 unless otherwise indicated).
Correlations between Hospital Complexity, RN Shortage, and Staffing on Nonintensive Care Units (N=201 Units)
Correlations between Hospital Complexity, RN Shortage, and Staffing on Intensive Care Units (N=78 U)
RN supply, the average number of licensed RNs per 1,000 population, across the 11 geographic areas in which the sample hospitals were located, ranged from 7.34 to 15.34 and was related to staffing levels on both ICUs and non-ICUs in the bivariate correlations. RN Hppd was higher in areas where the RN supply was higher (nonintensive care r = 0.123 [not statistically significant]; intensive care r = 0.336). It appears that a shortage of RNs may be offset by the use of LPNs as RN supply was negatively related to LPN Hppd on non-ICUs (r = −0.298) and on ICUs (r = −0.182 not statistically significant). Overtime may be used to compensate for fewer RNs in both non-ICUs (r = −0.164) and ICUs (r = −0.424). The bivariate correlations did not show an effect for RN supply on use of agency/traveler nurses, vacancy rates, or turnover rates. As noted above, hospital complexity was not significantly related to staffing levels in the ICUs, nor was unit size (see ). Also notable in the bivariate correlations were the trade-offs that hospitals make in staffing patient care units. Use of LPNs increased when supply and use of RNs was lower. There was also an increase in use of nurse assistants (CNA) when LPN hours decreased. CNAs bolster the total Hppd even in ICUs and were used more when there are fewer LPN hours.
Hospital complexity was positively correlated with total staffing, RN staffing, and licensed staffing on non-ICUs (Total Hppd r = 0.171; RN Hppd r = 0.280; RN mix r = 0.231, licensed Hppd r = 0.287, licensed mix r = 0.205) but not with LPNs or CNAs. Unit size was negatively related to total staffing and RN staffing on non-ICUs (Total Hppd r = −0.144; RN Hppd r = −0.265; RN mix r = −0.285), while it was positively related to LPN staffing (r = 0.187).
The bivariate correlation results might be misleading as the dependencies in the data set cannot be controlled. The multilevel, multivariate analyses, which did control for the nesting of units within hospitals and for the interrelationships among predictors, found similar results. presents the results for four of the outcome variables. There were few statistically significant results for the impact of hospital complexity or RN supply on Total Hppd, CNA Hppd, agency/traveler percent, overtime percent, vacancy rates, and turnover rate (results not provided here). Most of the nurse staffing variables were not normally distributed. All analyses were repeated using the natural log of the values that assumed approximately normal distributions. Inferential results were unchanged and the results reported here used the nontransformed variables for clarity in interpretation.
Mixed Linear Model Analyses Predicting Staffing Levels (N = 279)
The mixed model analyses showed that the RN Hppd () was determined by type of patient care unit with ICUs averaging 10 more hours of RN care per patient day than medical/surgical units. The complexity of the hospital affected RN staffing with each increasing complexity level associated with nearly 30 minutes (0.45 hours) more care per patient day. The size of the units affected staffing levels, with each increase of one bed resulting in a few minutes less care (1.6 minutes) for each patient. Finally, the supply of RNs in the surrounding area had a significant impact with each increase of one licensed RN per 1,000 population associated with 0.16 hours (10 minutes) more care per patient day.
The LPN staffing levels, on the other hand (), were not affected by hospital complexity or by unit size. Compared with medical/surgical units, LPNs were used less on stepdown units and ICUs. There was less use of LPNs in areas with higher RN supply, with 0.06 fewer hours of LPN care for each additional licensed RN per 1,000 population.
Effects similar to RN Hppd were seen for RN mix (). A richer mix was used on stepdown and ICUs than medical/surgical units. The percent of total hours of care provided by RNs increased in higher complexity hospitals, decreased on larger units, and increased in areas with greater RN supply. That is, in areas with one more licensed RN per 1,000 population, the proportion of hospital care provided by RNs increased 1.0 percent and hospitals increased the RN mix by 2.5 percent for each level of increased complexity. Licensed mix was similarly but not as strongly related to complexity and was not related to RN supply ().