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Original Investigation |

Comparison of the Value of Nursing Work Environments in Hospitals Across Different Levels of Patient Risk

Jeffrey H. Silber, MD, PhD1,2,3,4,5,6; Paul R. Rosenbaum, PhD3,7; Matthew D. McHugh, PhD, JD, RN, MPH3,4,8; Justin M. Ludwig, MA5; Herbert L. Smith, PhD4,9,10; Bijan A. Niknam, BS5; Orit Even-Shoshan, MS3,5; Lee A. Fleisher, MD3,6; Rachel R. Kelz, MD, MSCE3,11; Linda H. Aiken, PhD, RN3,4,8,9,10
[+] Author Affiliations
1Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia
2Department of Health Care Management, Wharton School, University of Pennsylvania, Philadelphia
3Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia
4Center for Health Outcomes and Policy Research, University of Pennsylvania, Philadelphia
5Center for Outcomes Research, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
6Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia
7Department of Statistics, Wharton School, University of Pennsylvania, Philadelphia
8School of Nursing, University of Pennsylvania, Philadelphia
9Population Studies Center, University of Pennsylvania, Philadelphia
10Department of Sociology, School of Arts and Sciences, University of Pennsylvania, Philadelphia
11Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia
JAMA Surg. 2016;151(6):527-536. doi:10.1001/jamasurg.2015.4908.
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Importance  The literature suggests that hospitals with better nursing work environments provide better quality of care. Less is known about value (cost vs quality).

Objectives  To test whether hospitals with better nursing work environments displayed better value than those with worse nursing environments and to determine patient risk groups associated with the greatest value.

Design, Setting, and Participants  A retrospective matched-cohort design, comparing the outcomes and cost of patients at focal hospitals recognized nationally as having good nurse working environments and nurse-to-bed ratios of 1 or greater with patients at control group hospitals without such recognition and with nurse-to-bed ratios less than 1. This study included 25 752 elderly Medicare general surgery patients treated at focal hospitals and 62 882 patients treated at control hospitals during 2004-2006 in Illinois, New York, and Texas. The study was conducted between January 1, 2004, and November 30, 2006; this analysis was conducted from April to August 2015.

Exposures  Focal vs control hospitals (better vs worse nursing environment).

Main Outcomes and Measures  Thirty-day mortality and costs reflecting resource utilization.

Results  This study was conducted at 35 focal hospitals (mean nurse-to-bed ratio, 1.51) and 293 control hospitals (mean nurse-to-bed ratio, 0.69). Focal hospitals were larger and more teaching and technology intensive than control hospitals. Thirty-day mortality in focal hospitals was 4.8% vs 5.8% in control hospitals (P < .001), while the cost per patient was similar: the focal-control was −$163 (95% CI = −$542 to $215; P = .40), suggesting better value in the focal group. For the focal vs control hospitals, the greatest mortality benefit (17.3% vs 19.9%; P < .001) occurred in patients in the highest risk quintile, with a nonsignificant cost difference of $941 per patient ($53 701 vs $52 760; P = .25). The greatest difference in value between focal and control hospitals appeared in patients in the second-highest risk quintile, with mortality of 4.2% vs 5.8% (P < .001), with a nonsignificant cost difference of −$862 ($33 513 vs $34 375; P = .12).

Conclusions and Relevance  Hospitals with better nursing environments and above-average staffing levels were associated with better value (lower mortality with similar costs) compared with hospitals without nursing environment recognition and with below-average staffing, especially for higher-risk patients. These results do not suggest that improving any specific hospital’s nursing environment will necessarily improve its value, but they do show that patients undergoing general surgery at hospitals with better nursing environments generally receive care of higher value.

Figures in this Article


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Figure 1.
Thirty-Day Mortality and 30-Day Cost by Patient Risk Level

The x-axis represents the average risk of each individual matched pair; y-axis, the difference in outcome (focal-control) inside each matched pair. A point falling on the horizontal line at 0 represents no difference between outcomes of the 2 patients in the matched pair; a point falling below the line, a better outcome for the focal vs control patient. LOWESS confidence bands for the central tendency line were produced using the bootstrap method. The box plots describe the distribution of predicted risk from the fifth to the 95th percentiles. A, The mortality advantage from attending a focal hospital increases with escalating patient risk. OR indicates odds ratio. B, Only small and mostly insignificant cost differences are seen between focal and control hospitals. DIF indicates difference. C, The focal patients have lower costs when differences in the nurse-to-bed (NTB) ratio are not included in the costing formula. DIF indicates difference.

Graphic Jump Location
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Figure 2.
Comparing Value Between Better (Focal) and Worse (Control) Nursing Environments by Patient Risk

The x-axis represents the difference between the control minus focal patient matched pair for 30-day costs (A) or 30-day costs without adjusting for nurse-to-bed (NTB) differences across hospitals(B). The y-axis represents the difference between control minus focal matched pairs for 30-day mortality. The ellipses on these graphs represent the 95% joint confidence region for cost and quality. For each plot, we display 6 ellipses: 5 numbered ones including about the same number of patients (n = 5015 or 5016), and a central ellipse with a centered dot that is based on all patients (N = 25 076) (see Appendix 13 in the Supplement for further explanation of the size of the ellipses). The ellipses in A and B are identical with respect to value but differ in cost differences between focal and control patients. A, The second-highest risk group (ellipse 4) is completely above the horizontal line at y = 0, suggesting a significant advantage in quality for the focal group, while the intersection with the vertical line at x = 0 suggests that the increased costs in the focal group vs the control group did not reach statistical significance. B, This same risk group displays lower cost with better quality in the focal group compared with the matched controls. For the risk strata, avg indicates average.

Graphic Jump Location




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