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Do Nurse Staffing Ratios Work? New Research Says No.

Analysis  |  By Jennifer Thew RN  
   September 05, 2018

Advocates of mandated staffing ratios say they improve patient outcomes. A recent study finds otherwise.

Nurse-to-patient ratios are a hot button issue. Look no further than Massachusetts for an example. After a battle that included a legal challenge that put it before the state's Supreme Judicial Court, Baystate voters will see a ballot question on nurse-to-patient ratios in November.  

Proponents of the initiative say it would improve patient safety while opponents say it would be too costly for the healthcare system to support.

And now, to add fuel to the fire, new research by physician-researchers at Beth Israel Deaconess Medical Center finds Massachusetts' previous regulations regarding nurse-to-patient staffing ratios in intensive care units were not associated with improvements in patient outcomes.

"We hypothesized that Massachusetts ICU nurse staffing regulations would result in decreased complications and mortality for critically ill patients when compared with patients admitted to ICUs across the country unaffected by Massachusetts regulations," lead author Anica C. Law, MD, core faculty at the Center for Healthcare Delivery Science and staff physician in the Division of Pulmonary, Critical Care, and Sleep Medicine at BIDMC, says in a news release. "But we did not identify improvements in patient outcomes associated with the state’s nursing requirements."

The Mandate

In 2014, Massachusetts passed a law requiring 1-to-1 or 2-to-1 patient-to-nurse staffing ratios in intensive care units, as guided by a tool that accounts for patient acuity and anticipated care intensity.

Researchers examined records from 246 medical centers nationwide and compared patient outcomes in Massachusetts’ six academic ICUs with outcomes in 114 out-of-state academic ICUs before, during, and after the state mandate was implemented.

They reviewed tens of thousands of ICU admissions, focusing on the change in mortality rates for patients in Massachusetts’ academic ICUs before and after the mandate was implemented. This information was compared with patients hospitalized in out-of-state hospitals.

Other analyses looked at changes occurring at community, non-academic ICUs and among a group of the sickest patients who received support from a ventilator.  The research team also analyzed complication rates, including central line-associated bloodstream infections, catheter-associated urinary tract infections, hospital-acquired pressure ulcers, and patient falls with injury.

Staffing Ratio Results

Before and after the mandate's implementation, researchers found modest increases in ICU nurse staffing ratios—a change from 1.38 patients per nurse to 1.28 patients per nurse.

These increases were not significantly higher than staffing trends in states without state-mandated ICU staffing regulations. According to the researchers, this suggests nurse staffing increases in Massachusetts could not be attributed to the state legislation.

Additionally, the risk of mortality and risk of complications in Massachusetts’ ICUs remained stable after the law’s implementation, with no significant difference in trends compared to out-of-state hospitals.

"Our results suggest that the Massachusetts nursing regulations were not associated with changes in staffing or patient outcomes," Law says. "The modest changes in nurse staffing we saw in Massachusetts – approximately one extra nurse per 20-bed ICU per 12-hour shift – remained unassociated with changes in hospital mortality."

Yet, some research has reported different findings regarding nurse-to-patient ratios.  

When University of Pennsylvania nurse researcher Linda H. Aiken, PhD, FAAN, FRCN, looked at California's state mandated nurse-to-patient staffing ratios, her research team found that California hospital nurses cared for one less patient on average than nurses in the other states and that lower ratios were associated with significantly lower mortality.

Jennifer Thew, RN, is the senior nursing editor at HealthLeaders.

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