Executive summary: Evidence on Hospital Staffing and Outcomes – Implications for Washington State

In the early 2000s, the first studies emerged showing the negative effects on patient mortality of low registered nurse (RN) staffing levels in hospitals. Since that time, state legislators in Washington state and around the country have grappled with the question of how best to ensure public safety and protect the workforce when hospitals do not adequately staff.

This report summarizes the research demonstrating that nurse and nurse assistive personnel staffing levels are associated with patient safety and staff wellbeing. The next section reviews evidence on the effect of nurse staffing laws on staffing levels. It then presents Washington-specific data analysis derived from two national studies, in which the author participated, that locate Washington in this national debate. Lastly, it examines research on the outcomes of California’s staffing law and summarizes a major prospective experimental study that assesses outcomes of a nurse staffing mandate law in Queensland, Australia.

There are hundreds of studies on the outcomes of nurse staffing in the United States, and dozens more in other countries. Studies have shown that nurse staffing levels are significantly associated with the following:

• patient mortality and failure to rescue, using many different data sources and analytic approaches;
• adverse patient events, including: hospital acquired pneumonia, unplanned extubation, respiratory failure and cardiac arrest in ICUs, decubitus ulcers, falls, urinary tract and surgical site infection, as well as longer restraint application duration, more medication errors, and longer times to diagnosis in the emergency room;
• longer lengths of stay, higher rates of 30-day patient readmission and lower patient satisfaction;
• nurse burnout, job satisfaction, and occupational harms, specifically needle stick injuries; and
• cost savings in health services that surpass the expense of additional nurses.

The literature also suggests nurse staffing levels interact with other elements in the nurse practice environment, and that the effect of nurse staffing on patient outcomes tends to be largest in hospitals with poor work environments, and in hospital units with the sickest patients.

There is less research on nursing assistive personnel and quality of care, but at least three important studies suggest that higher support staff levels are associated with reduced patient mortality and better patient satisfaction.

Fourteen states have responded to this evidence with legislation. Three general approaches have been used: (1) directly mandating nurse to patient levels, (2) requiring staffing committees that include bedside nurses (in the hopes that their perspectives will be considered by hospital administrators), and (3) public reporting of staffing levels (in the hopes that consumers will “vote with their feet” and put market pressure on hospitals). Just one state, California, mandated minimum nurse to patient staffing ratios for all hospital units. The other 13, including Washington, have tried the two “softer” types of laws. In 2008, the Washington State Legislature enacted a required staffing committee law, and in 2017, enhanced the legislation by adding a public reporting requirement and additional enforcement and complaint mechanisms.

The first national level study to assess these three legal approaches used a “difference in difference” design to compare staffing changes in states utilizing one of the three approaches to states with no law of any kind, during the period 2003 to 2018. The study concluded that only the mandate has had any significant effect on nurse and nurse-support staffing levels.

Data on Washington extracted from this study showed that, while hospital RN hours per patient day increased by 55% in California during those years, the increase in Washington was just 6%. In 2018, California had reached an average of 9.02 RN hours per adjusted patient day, while in Washington it was 6.8.

Another study looking at staffing levels needed to improve patient satisfaction showed the important role that RNs and nursing assistive personnel play. Using the same data set and approach as the national study, the Washington-specific analysis conducted for this report suggested that, depending on the patient satisfaction subscale, between 5% and 13% of Washington hospital observations would need to increase RN staffing to see any marginal benefit in patient satisfaction. Only 2-5% (depending on the subscale) of hospital observations in Washington have reached this peak level. For nursing assistant (NA) personnel, these patterns are even more dramatic. Between 33% and 75% of hospital observations had NA staffing levels so low that their contribution to patient satisfaction was below zero. Just 2-6% of hospital observations had NA staffing levels high enough to reach the peak marginal contribution.

The California law has been studied by scores of researchers. Results show not only that nurse staffing increased, but that skill mix (RNs as percent of all nursing staff) did not suffer. One major study comparing California to two other states found improvements in some areas of quality of care. A longitudinal survey showed increases in nurse job satisfaction since the law's implementation in 2004. Two very early studies using a convenience sample found no improvements, and three later studies with more rigorous difference in difference designs found mixed results.

Internationally, there has also been considerable research and policy action on nurse staffing levels. Ireland, Wales, Scotland and two states in Australia have implemented mandates. The case of Queensland, Australia was recently evaluated using the first ever prospective experimental design. They found significant improvements in patient safety in the intervention hospitals, when compared to control hospitals. The authors also concluded that savings as a result of avoidable health services surpassed the costs of increased staffing.

This summary of available research suggests that Washington could do more to ensure safe staffing in its hospitals. It is important for policymakers to understand this varied and robust evidence as they consider whether to make Washington the second state in the nation to mandate safe staffing.