Nurse Staffing Ratios: A Comprehensive Research Analysis in Relation to Question 1

There are no published peer-reviewed studies that support the imposition of specific nurse-to-patient ratios. While some of the extensive studies link improved patient outcomes to improved RN staffing, none of the studies attribute the improvements to staffing alone or state that setting limits to the number of patients that nurses care for will automatically result in improved outcomes.  To the contrary, many of the studies point to the adverse, unintended consequences of imposing inflexible nurse-to-patient ratios.

The Massachusetts Association of Colleges of Nursing, comprised of Deans and Directors of nursing programs of higher education in Massachusetts serve as leading voices and advocates for education. In our roles as nurse leaders, educators and scholars, we examine, assess, and evaluate evidence in order to arrive at conclusions that then serve to direct care improvement and change. We have reviewed more than 100 studies related to nurse staffing to a range of outcomes that would impact patients, nurses and acute care settings. From this we have concluded the following:

  • Nurse staffing is related to some patient outcomes – under some circumstances
  • There are other factors that equally or more strongly influence patient outcomes, including:
    • The education level and level of experience (skill mix) of nurses
    • The work environment
    • Collaboration and communication among the whole care team
  • Most researchers agree that while ‘adequate’ staffing levels are important, maintaining flexibility in staffing is crucial, and that widespread policy mandates are unlikely to yield the intended effects, but are highly likely to cause or result in significant unintended consequences, as observed in California.

“Mandating minimum nurse staffing ratios may seem like an “easy fix” of the problem; however, we must consider how these ratios can be met, the potential difficulty for hospitals to meet these ratios in the fraying safety net, and possible unintended consequences.” [1]

-Conway, et al 2008, Journal of Hospital Medicine

A review of the existing scholarship on the issue finds that:

  • NO study supports the specific ratios (or any ratios) as proposed in Question 1
  • NO study has established a causal relationship between nurse staffing and patient outcomes
  • There has been NO systematic improvement in patient outcomes in California following the implementation of their nurse staffing law.

 

“[T]he evidence offers little direct guidance for those wishing to set staffing levels on wards. Most studies simply offer an estimate of the average effect of changing staff levels. The estimates are prone to bias and, crucially, give no clear indication of the actual staffing levels to be achieved. In effect, the answer to the question of how many nurses to deploy on a ward is ‘more.’” [2]

-Griffiths, et al 2017, Health Work: Evidence Briefs

 

What the Research Says About Factors That Affect Patient Outcomes

Lack of Consensus on What Constitutes “Adequate” Staffing

Despite the thousands of studies looking at the effects of nurse staffing and other variables on patient outcomes and quality of care, many researchers acknowledge that there is no agreed-upon fixed ratio or even consensus on the association between nurse staffing and many specific patient outcomes.[3]

“But what’s adequate? It’s difficult to generalize because nurse-patient ratios depend on factors that can vary, including characteristics of the patient, nurse, and work environment. A nurse-patient ratio that’s sufficient on one unit might not be on another. And there’s no scientific evidence to support specific nurse-patient ratios. Where minimum nurse-patient ratios have been legislated, as in California, they reflect political compromises among hospitals, insurers, nurses, and the public, rather than hard science.” [4]

-Unruh, 2008, The American Journal of Nursing

Moreover, some researchers make the case that even attempting to establish ideal or optimal nurse-to-patient ratios is an exercise in futility because patient care is so complex, and individuals and technology, treatment and quality improvement initiatives are constantly changing as new information becomes available. They argue that even if such optimal ratios were identified, they would likely be outdated within a short period of time.[5] Further, optimal ratios are unlikely to be universal across hospitals due to the high variations in patient characteristics, technology, staffing, resources, and other pertinent variables.[6]

Jack Needleman, nursing researcher at the University of California-Los Angeles, is one of the experts frequently cited by the supporters of Question 1. He has an extensive body of research on nurse staffing, including two of the most prolific studies looking at nurse staffing and patient mortality that have been conducted,[7] and yet even he has not spoken in favor of widespread staffing mandates. Though he is a strong advocate for ‘adequate’ levels of both nurse staffing and nurse education, he questions what constitutes ‘adequate’ in a 2015 publication.[8] In addition, his co-author on multiple publications, Peter Buerhaus, is the most out-spoken nursing researcher against staffing mandates.[9]

“Staffing matters. But even accepting this conclusion, the question remains: what is the appropriate level of staffing to assure care is delivered safely and reliably and nurses have the time to meet the needs of their patients?” [10]

-Needleman, 2015, Nursing Economics

 

 

 

Nurse Staffing and Patient Outcomes

Many nursing-related variables have been studied, but none more so than nurse staffing levels. While the research shows strong associations between nurse staffing and patient mortality, surprisingly, quality measures that are widely considered to be nursing-sensitive- or heavily influenced by nursing care- are not consistently associated with nurse staffing levels. This suggests that there are other important factors that contribute to patient safety and outcomes.

“Although past studies have recognized an association between adequate nurse staffing and quality of care, patient safety, and mortality, such one-dimensional perspective is much too simplistic and dangerously flawed given the challenges associated with patient needs and healthcare delivery systems in today’s complex and multifaceted environments.” [11]

-Wallace, 2013, Nursing Management

Furthermore, multiple studies have found that there appear to be diminishing returns on investments of staffing, suggesting that the benefits of nurse staffing increases are likely to be biggest where nurse staffing levels were previously lowest. Research indicates that there may be some threshold above which increases in nurse staffing levels will not be associated with improvements in patient outcomes, and could possibly be associated with worse patient outcomes.[12] A 2008 study[13] suggests that this non-linear effect and the differences in strength of associations between nurse staffing and patient outcomes means that a “one-size-fits-all” approach to staffing would be an inefficient use of resources, as hospital budgets and characteristics vary and artificial staffing levels may draw funds away from other critical patient services and programs. All nurse researchers acknowledge a relationship between nursing care and patient outcomes. But acknowledging a relationship does not equate to supporting a statewide staffing mandate that has the potential for serious unintended consequences.

 

Other Factors that Affect Patient Outcomes

Nursing care is complex. Being able to adapt to ever-changing patient needs means having the right education and training, as well as the flexibility to modify care and attention as needed. Nurses are as varied as the patients they care for, with a wide range of educational attainments from diplomas to advanced degrees and certification. Hospitals vary in the composition of their care teams (e.g., teaching hospitals versus smaller community hospitals), medical technology, facilities, and physical layouts.

“Hospitals with higher staffing seem to have other unmeasured characteristics that contribute to better outcomes. For example, changes in the work environment or changes in nursing skill mix may contribute to better patient outcomes, whether or not they are accompanied by increases in nurse staffing.” [14]

-Sochalski et al, 2008, Medical Care

Research has shown many factors influence patient outcomes, including the education and experience of nurses, the work environment, nurse-physician communication, and collaboration among the whole medical care team, among others. The following is a brief summary of the research on these factors and how they relate to both patient outcomes and staffing.

Nurse Education and Experience

Many studies have looked at the relationship between nurses’ level of education and/or experience and patient outcomes; almost all have found significant, positive correlations between them.[15] For example, a 2014 study[16] by Aiken and colleagues concluded that nurse staffing cuts can negatively affect patient outcomes, but that a higher proportion of nursing staff with bachelor’s degrees or higher could mitigate these effects and reduce preventable hospital deaths.

“Nurse-related staffing formulas and guidelines assume that all nurses practice with the same level of vigilance and expertise. They also assume that all nurses exhibit the same level of critical thinking and clinical judgment and are able to access vital resources in a timely fashion when a patient’s condition deteriorates or his or her safety and well-being are at risk." [17]

-Wallace, 2013, Nursing Management

 In fact, the link between higher educated nurses and improved patient outcomes is so strong that in 2010 the IOM released another report titled The Future of Nursing: Leading Change, Advancing Health that calls for a campaign to increase the percentage of RNs with bachelor’s degree or higher to 80% by 2020. A follow-up to the 2010 report[18] found that while there was still work to be done on the recommendations, much progress had been made in the five years since its publication. Improvements to nursing education and increases in RN educational attainment have been included as recommendations in many reports.[19]

Of note, Massachusetts RNs have higher rates of educational attainment than the national average (58% to 55.2% with a BSN or higher). When looking at younger nurses (under 35 years), the rate is substantially higher, and virtually at the benchmark identified in the IOM report (79.3%).[20] This above-average educational attainment of Massachusetts RNs could partially explain the high quality scores that Massachusetts hospitals typically receive.

Work Environment

There are several studies that measure work environment, either alone or with other variables, in relation to patient outcomes. The strong positive association between work environment and patient outcomes is fairly consistent across the literature.[21] At least one study suggests that work environment can be a strong modifier of patient outcomes relative to staffing, finding that the effects of nurse staffing on patient outcomes was significantly dependent upon the quality of the work environment, with effects being maximized in those with good work environments and almost non-existent in poor work environments.

“The most important new finding in this study is that the impact of nurse staffing is contingent upon the quality of the nurse work environment, and vice versa. Absent a good work environment, reducing nurse workloads by adding additional nurses, a costly proposition, may have little consequence.” [22]

-Aiken et al, 2011, Medical Care

In fact, the widespread effect of work environment on both nurse and patient outcomes inspired the creation of the American Nurses Credentialing Center (ANCC) Magnet Recognition Program®. Organizations recognized as Magnet® are, “recognized for superior nursing processes and quality patient care, which leads to the highest levels of safety, quality, and patient satisfaction…” Of note, eight Massachusetts hospitals are recognized as Magnet hospitals, with several more on the journey toward Magnet accreditation.

A study on the effects of several factors of nursing environment on nurse-reported patient outcomes found that nurse-physician relations, nurse involvement in decision-making, and physical work environment all contributed to nurses’ ratings on the quality of care. Due to the world-wide RN shortage that both exists and is anticipated as the aging RN population moves closer to retirement age, the researchers sought specifically to determine what factors best influence patient outcomes aside from staffing. They found that improvements to multiple areas of the work environment led to improvements in patient outcomes while holding RN staffing levels constant.[23]

The Whole Care Team

Several studies have looked at the role of the whole medical team, including physicians and nursing assistants, in relation to patient outcomes and have found significant associations between medical team staffing and mortality.[24] Nurses are not the only ones caring for patients; staffing assessments should take into account the whole team.

“Each professional group and ancillary support team involved in the delivery of healthcare services must be responsible for determining their own staffing needs based on their respective care models for practice, including respectful collaboration, and identifying resources they must have onsite to keep patients safe and prevent adverse outcomes." [25]

-Wallace, 2013, Nursing Management

One study looked at the effect of good nurse-physician collaboration on patients’ hospital-acquired infections. The researchers’ findings support other existing research linking nurse-physician collaboration with better patient outcomes, including outcomes related to mortality and infections.[26] In another study, researchers looking at the relationship between nurse staffing and missed nursing care speculated from their findings that the biggest possible factor related to missed care was a lack of teamwork between nurses and nursing assistants. The authors also acknowledge that there should be a larger emphasis on teamwork of the whole medical care team with more clearly defined roles and responsibilities of individual team members. They suggest that it is not so much the number of staff members leading to missed care as the lack of teamwork among types of staff that is leading to incorrect assumptions between staff members as to who is providing specific needs and care.[27] Other research has shown that interventions to improve teamwork can help to improve performance and reduce errors.[28]

 

The Need for Flexibility and Caution Against Staffing Mandates

Opponents of mandated staffing ratios value the work that nurses do, and do not discount the associations between nursing care and patient outcomes. Rather, opponents of mandated staffing ratios recognize the myriad of operational and economic complexities involved in nurse staffing and patient care.[29] Beyond the factors just described, patient and hospital characteristics – such as varying patient mix and acuity, the physical facility layout and resources available at different hospitals, and the evolution of technology – all affect patient care and outcomes. Even ardent proponents of higher levels of nurse staffing acknowledge the high costs involved, as well as the influence of other factors affecting patient outcomes, and generally stop short of advocating for state or federal legislation setting specific, rigid ratios.[30]

“Our calculations suggest that it is difficult to set fixed standard RN ratios. Indeed, fixed minimum RN-to-patient ratios implemented in California did not provide the expected patient safety benefits. To maintain a reasonable staffing level in the face of an increasing RN shortage, hospitals may need to reduce capacity. Mandatory nurse-to-patient ratios without legislative agreement to increase reimbursement may result in administrative decisions to reduce support staff positions and investments in other quality initiatives.” [31]

Kane et al, 2007 ,Medical Care

Beyond the research limitations and complexities, opponents of mandated staffing ratios argue that the very notion of implementing wide-scale staffing mandates without regard to local context and considerations just doesn’t make sense, financially or operationally. [32]  Attempting to apply a one-size-fits-all staffing ignores these complexities and resources that vary across organizations.

 

The California Experience

In 1999, the California legislature passed a bill (AB 394) mandating minimum nurse-to-patient ratios in all acute care hospitals. Although the bill was signed in 1999, the actual ratios were not established until 2003 following substantial research and stakeholder debate. Nurse-to-patient ratios were initially implemented in 2004 and then increased using a phased-in approach in some units, with new minimum thresholds implemented in 2005 and 2006, and the final thresholds for certain units implemented in 2008. Currently, California is the only state in the US to have state-wide, mandatory minimum nurse staffing ratios in hospitals.

There are several key differences between the California law and the ballot proposal from the MNA:

  • California hospitals had five years between the legislation passing and the ratios going into effect; Massachusetts hospitals would need to come into compliance by January 1, 2019, or just 37 business days after the ballot.
  • The mandated nurse-to-patient ratios are more lenient in California than in the MNA’s proposal, meaning that Massachusetts hospitals will face higher staffing needs than California.
  • California’s law allows both registered nurses (RNs) and up to 50% licensed practical/vocational nurses (LPNs/LVNs) to count towards the ratio requirement; however, the MNA’s Question 1 proposal requires ratios to only be met by RNs.
  • Violations of the ratio mandate do not result in monetary civil penalties in California, in contrast to the MNA’s proposal which includes fines of up to $25,000 per incident, per day.
  • The California law’s legislative structure permits waivers for small/rural hospitals,[33] while Question 1 explicitly forbids such waivers.

Patient Outcomes and Emergency Department Wait Times in California

Though the supporters of Question 1 repeatedly claim that “the results have been universally positive,” the evidence from the research suggests otherwise. More than a dozen primary studies and multiple systematic reviews have assessed the impact of California nurse staffing ratios on patient outcomes and all conclude the same thing: while nurse staffing has increased, the intended patient safety and outcome benefits have not been realized. Far from being “universally positive,” the vast majority of research looking at patient outcomes before and after California became the first and only state in the US to have mandated nurse staffing ratios concludes there has been little to no improvement for the majority of patient outcomes measured.[34] The October 2018 report from the state healthcare’s watchdog, the Health Policy Commission, made a similar conclusion.[35]

“The findings from the majority of these studies do not support the assumption that increases in nurse staffing would lead to better quality of care, improvements in patient safety, or increased patient satisfaction.” [36]

Serratt, 2013, Journal of Nursing Administration

The supporters of Question 1 repeatedly make the vastly misleading claim that emergency department (ED) wait times in California are shorter than those in Massachusetts and that it is because “ratios work.” There is scant evidence for this claim that ED wait times improved in California following the implementation of mandated ratios. In fact, studies show that ED wait times increased, despite fewer people seeking care.[37] Further, the most recent data available from the Centers for Medicare and Medicaid Services (CMS) shows that for the majority of ED-related measures, Massachusetts scores better than California.[38]

California hospital leaders have reported bottlenecks caused by mandated staffing ratios, where hospitals may have empty beds, but not enough nurses to staff them to stay in compliance with the ratios.[39] Despite nursing union promises of nurses coming back into the workforce and ratios being cost-effective, the extreme nursing shortage in California remains[40] and many hospitals – particularly safety-net facilities – are not staffed fully in compliance with the ratio law.[41] Therefore, because of the arbitrary mandate, patients wait in the ED instead of moving to inpatient units for timely, condition-specific inpatient care, despite the fact that there may be empty beds that would otherwise be available. [42]

Increased Costs and Hospital Closures

Mandating staffing levels without any additional funding – either from the government or from increased insurance reimbursement – will disproportionately affect hospitals, as evidenced by California. Research on care following the implementation of ratios found that some hospitals decreased uncompensated care,[43] cut services and programs,[44] and disproportionately affected safety-net hospitals.[45]

“California hospitals benefitted from increased availability of nurses due to the uniquely high number of hospital closures in the state…[S]taffing requirements may have contributed to financial hardships for many California hospitals.” [46]

Munnich, 2014, Health Economics

One study found that not only were safety-net hospitals harmed by needing to hire more staff, with the resultant nurse wage inflation from ratios, they likely lost RNs to other hospitals that could afford to pay more. The safety-net facilities were therefore left with a lower skill mix of nurses than non-safety net hospitals and were more likely to be out of compliance with the ratios. In fact, this effect was so severe that the researchers, including Linda Aiken and Matthew McHugh who are widely cited by Question 1 supporters, cautioned that policy makers should consider alternative approaches to increase staffing. For example, they suggested pairing funding with the staffing mandate for hospitals in need, or creating targeted policies that would assist hospitals with the lowest staffing levels, or endorsing government initiatives to help increase the supply of nurses.[47]

A 2014 study[48] on labor effects found that the rate of California hospital closures between 1986 and 2008 was more than double the national rate (25% vs. 10.5%)  This coincides with the signing of the legislation in 1999 and ramping up of nurse staffing in the years leading up to the law’s implementation in 2004. The authors reported 15 hospital closures in the years surrounding the implementation of the staffing legislation (2003-2005).[49]

California experienced a particularly sharp decline [in hospitals] between 2002 and 2004 and changes in the number of hospitals decreased at an increasing rate after this period.” [50]

Munnich, 2014, Health Economics

A healthcare management and economics researcher from the University of Pennsylvania studied California hospitals relative to similar matched hospitals across the country and found that overall, California hospitals were more than twice as likely to close as hospitals in other states during the same time period (1999-2006) from the passing of the staffing legislation to two years post-implementation.[51] California hospitals with the lowest staffing levels, which also tended to have the lowest operating margins, were more than four times more likely to close than similar hospitals in other states. Similar effects were found for emergency departments. The researcher used a rigorous methodology that accounted for other significant concurrent costs to hospitals and determined that the link between nurse staffing ratios and hospital closures was “likely causal.”[52]

 

How the Research is Misrepresented

The Massachusetts Nurses Association (MNA), which is the primary organization behind Question 1, has compiled dozens of articles over the years and posted them on its website.[53] For each article or topic, the MNA states a series of nurse-staffing-related claims that upon closer inspection have proved to be misrepresentations. Many of the articles actually refute the MNA’s arguments for ratios or suggest alternative means to improving patient outcomes. More than 30 of the authors the MNA has cited have expressed words of caution or even argued against the concept of fixed ratios. These include many of the most prolific nursing researchers such as Peter Buerhaus,[54] Barbara Mark,[55] Patricia Stone,[56] Joanne Spetz,[57] Sean Clarke,[58] Jean Ann Seago,[59] Robert Kane,[60] Julie Sochalski,[61] and even Linda Aiken and Matthew McHugh.[62]

“The overall conclusion we draw from these results is that it will likely be necessary to vary staffing hours and staff mix depending on which patient outcome or outcomes you wish to achieve…Additionally, if patient care unit characteristics other than staffing hours and skill mix can be captured, it may be possible to identify other variables that can be varied to achieve positive patient outcomes.” [63]

Seago et al, 2006, Journal of Nursing Administration

For example, the MNA frequently cites a seminal 2002 study by Linda Aiken and colleagues as showing definitive proof that nurses in medical-surgical units should never care for more than four patients at a time. But while Aiken and colleagues did find decreased mortality rates associated with nurses caring for fewer patients, they specifically state that their research should not be used to inform specific staffing policies.

“Our results do not directly indicate how many nurses are needed to care for patients or whether there is some maximum ratio of patients per nurse above which hospitals should not venture.” [64]

Aiken et al, 2002, Journal of the American Medical Association

Other studies that the MNA cites in support explain the nuances to their research findings and the many complexities involved in patient care and staffing decisions.

“Although staffing is shown to be associated with infection rates, “association” is not the same as “cause.” Other variables include RN experience and use of temporary workers. Moreover, “failure to rescue” is generally related to hospital characteristics and not hand washing or treatment errors. These inconsistencies suggest a missing layer- a systems layer that has not yet been identified.” [65]

Jackson et al, 2002, American Journal of Infection Control

The MNA even misrepresented the conclusions of one of the most prestigious independent medical groups in the United States, the National Academy of Medicine (formerly the Institute of Medicine) by implying that the group recommends nurse staffing ratios such as those proposed in their ballot.

“A number of researchers studying hospital staffing levels and patient outcomes have found that evidence does not yet exist to indicate the necessary (minimum) or ideal (optimal) staffing across the various types of hospital inpatient care units…The committee agrees that generalizing the results of studies of the effects of hospital-wide staffing on patient safety to specific types of hospital units is inappropriate.” [66]

Institute of Medicine, 2004, National Academies Press.

The MNA frequently refers to research done by Boston College Associate Professor of Nursing and former MNA president, Judith Shindul-Rothschild and colleagues as evidence to support their ballot proposal. We have reviewed the research published by them and found that, overall, there are several methodological limitations that weaken their conclusions. These limitations, which are described in each papers’ discussion sections, include a lack of controls for relevant factors that are known to influence patient outcomes, as well as other data constraints.[67] Some of their research also uses staffing and patient outcomes data from misaligned time periods such that valid comparisons of the influence of staffing on patient outcomes are not possible.[68]

“[T]he data analyzed in this study did not account for comorbid medical diagnoses, psychiatric conditions, or socioeconomic factors that may also influence patients’ satisfaction with pain management. HCAHPS is case mix adjusted; however, scores are not adjusted for type of specialty care or diagnosis, which have been found to be significantly associated with HCAHPS score. Participation in HCAHPS is voluntary, and response bias may influence patients’ perception of pain control.” [69]

Shindul-Rothschild et al, 2017, Pain Management Nursing

Further, in print and speaking, both the MNA and Dr. Shindul-Rothschild omit some of the research findings in their descriptions of it and their claims of how it supports setting rigid staffing ratios. For example, a 2014 study by Shindul-Rothschild and colleagues found that Massachusetts had significantly better patient self-reports of the quality of nursing care than the comparison states in the study, California and New York,[70] yet they frequently claim that California nurses have more time with their patients and that patients in California are more satisfied with their care.

“More research is needed on the numbers and mix of ED professionals, patient demographics, and severity, as well as overall hospital characteristics, to more fully understand the dynamics that contribute to ED crowding. Important community factors to consider include access to urgent care and outpatient clinics, case management availability, and other non-hospital-based supports that may contribute to the 62% variation in ED door to diagnostic evaluation that remained unexplained in this study.” [71]

Shindul-Rothschild et al, 2017, Journal of Emergency Nursing

 

Conclusion: The Scientific Evidence Argues Against Question 1

Cutting through the clutter of competing claims, we find:

  • There is NO evidence to support specific nurse-to-patient ratios.
  • Patient care is complex and staffing levels should be determined within the context of local patient populations, nurse and other team member characteristics, and resource availability.
  • There were many unintended consequences of the nurse staffing mandate in California.

 

“The sheer number of variables and myriad linkages depicted suggest why precise evidence-based formulas for deploying nursing staff to ensure safe, high-quality patient care are impossible based on the knowledge on hand. In fact, such prescriptions may never be possible.” [72]

-Clarke & Donaldson, 2008, Patient Safety and Quality: An Evidence-Based Handbook for Nurses

 

[1] Conway, P. H., Tamara Konetzka, R., Zhu, J., Volpp, K. G., & Sochalski, J. (2008). Nurse staffing ratios: trends and policy implications for hospitalists and the safety net. Journal of Hospital Medicine, 3(3), 193-199.

[2] Griffiths, P., Dall'ora, C., & Ball, J. (2017). Nurse staffing levels, quality and outcomes of care in NHS hospital wards: what does the evidence say?. Health Work: Evidence Briefs, 1(1).

[3] See, for example:

  1. Griffiths, P., Ball, J., Drennan, J., Dall’Ora, C., Jones, J., Maruotti, A., ... & Simon, M. (2016). Nurse staffing and patient outcomes: Strengths and limitations of the evidence to inform policy and practice. A review and discussion paper based on evidence reviewed for the National Institute for Health and Care Excellence Safe Staffing guideline development. International Journal Of Nursing Studies, 63, 213-225.;
  2. Kane, R. L., Shamliyan, T. A., Mueller, C., Duval, S., & Wilt, T. J. (2007). The association of registered nurse staffing levels and patient outcomes: systematic review and meta-analysis. Medical Care, 45(12), 1195-1204.;
  3. Unruh, L. (2008). Nurse staffing and patient, nurse, and financial outcomes. AJN The American Journal of Nursing, 108(1), 62-71.;
  4. Welton, J. M. (2014). Massachusetts New Nurse Staffing Law. Journal of Nursing Administration, 44(11), 553-555.

[4] Unruh, L. (2008). Nurse staffing and patient, nurse, and financial outcomes. AJN The American Journal of Nursing, 108(1), 62-71.

[5] See, for example:

  1. Buerhaus, P. I. (2009). Avoiding mandatory hospital nurse staffing ratios: An economic commentary. Nursing Outlook, 57(2), 107-112.;
  2. Buerhaus, P. I. (2010). It's time to stop the regulation of hospital nurse staffing dead in its tracks. Nursing Economics, 28(2), 110.;
  3. Douglas, K. (2010). Ratios-If it were only that easy. Nursing Economics, 28(2), 119.;
  4. Spetz, J. (2005). Public policy and nurse staffing: what approach is best?. Journal of Nursing Administration, 35(1), 14-16.

[6] See, for example:

  1. Clarke, S. P., & Donaldson, N. E. (2008). Nurse staffing and patient care quality and safety. An excerpt from Patient Safety and Quality: An Evidence-Based Handbook for Nurses.
  2. Mark, B. A., Hughes, L. C., & Jones, C. B. (2004). The role of theory in improving patient safety and quality health care. Nursing Outlook, 52(1), 11-16.

[7] See:

  1. Needleman, J., Buerhaus, P., Mattke, S., Stewart, M., & Zelevinsky, K. (2002). Nurse-staffing levels and the quality of care in hospitals. New England Journal of Medicine346(22), 1715-1722.
  2. Needleman, J., Buerhaus, P., Pankratz, V. S., Leibson, C. L., Stevens, S. R., & Harris, M. (2011). Nurse staffing and inpatient hospital mortality. New England Journal of Medicine, 364(11), 1037-1045.

[8] Needleman, J. (2015). Nurse staffing: the knowns and unknowns. Nursing Economics, 33(1), 5-7.

[9] See, for example:

  1. Buerhaus, P. J. (1997). What is the harm in imposing mandatory hospital nurse staffing regulations?. Nursing Economics, 15(2), 66-73.
  2. Buerhaus, P. I. (2009). Avoiding mandatory hospital nurse staffing ratios: An economic commentary. Nursing Outlook, 57(2), 107-112.
  3. Buerhaus, P. I. (2010). It's time to stop the regulation of hospital nurse staffing dead in its tracks. Nursing Economics, 28(2), 110.
  4. Douglas, K., & Kerfoot, K. M. (2011). A Provocative Conversation With Peter I. Buerhaus, PhD, RN, FAAN. Nursing Economics, 29(4), 169.

[10] Needleman, J. (2015). Nurse staffing: the knowns and unknowns. Nursing Economics, 33(1), 5-7.

[11] Wallace, B. C. (2013). Nurse staffing and patient safety: What's your perspective?. Nursing Management, 44(6), 49-51.

[12] See, for example:

  1. Sochalski, J., Konetzka, R. T., Zhu, J., & Volpp, K. (2008). Will mandated minimum nurse staffing ratios lead to better patient outcomes?. Medical Care, 46(6), 606-613.;
  2. Mark, B. A., Harless, D. W., McCue, M., & Xu, Y. (2004). A longitudinal examination of hospital registered nurse staffing and quality of care. Health Services Research, 39(2), 279-300.

[13] Sochalski, J., Konetzka, R. T., Zhu, J., & Volpp, K. (2008). Will mandated minimum nurse staffing ratios lead to better patient outcomes?. Medical Care, 46(6), 606-613.

[14] Sochalski, J., Konetzka, R. T., Zhu, J., & Volpp, K. (2008). Will mandated minimum nurse staffing ratios lead to better patient outcomes?. Medical Care, 46(6), 606-613.

[15] See, for example:

  1. Blegen, M. A., Goode, C. J., Park, S. H., Vaughn, T., & Spetz, J. (2013). Baccalaureate education in nursing and patient outcomes. Journal of Nursing Administration, 43(2), 89-94.;
  2. Aiken, L. H., Sloane, D. M., Bruyneel, L., Van den Heede, K., Griffiths, P., Busse, R., ... & McHugh, M. D. (2014). Nurse staffing and education and hospital mortality in nine European countries: a retrospective observational study. The Lancet, 383(9931), 1824-1830.;
  3. Estabrooks, C. A., Midodzi, W. K., Cummings, G. G., Ricker, K. L., & Giovannetti, P. (2005). The impact of hospital nursing characteristics on 30‐day mortality. Nursing Research, 54(2), 74-84.;
  4. Yakusheva, O., Lindrooth, R., & Weiss, M. (2014). Economic evaluation of the 80% baccalaureate nurse workforce recommendation: a patient-level analysis. Medical Care, 52(10), 864-869.

[16] Aiken, L. H., Sloane, D. M., Bruyneel, L., Van den Heede, K., Griffiths, P., Busse, R., ... & McHugh, M. D. (2014). Nurse staffing and education and hospital mortality in nine European countries: a retrospective observational study. The Lancet, 383(9931), 1824-1830.

[17] Wallace, B. C. (2013). Nurse staffing and patient safety: What's your perspective?. Nursing Management, 44(6), 49-51.

[18] National Academies of Sciences, Engineering, and Medicine. (2016). Assessing progress on the Institute of Medicine report The Future of Nursing. National Academies Press.

[19]See, for example:

  1. Joint Commission on Accreditation of Healthcare Organizations. (2002). Health care at the crossroads: Strategies for addressing the evolving nursing crisis.;
  2. Buerhaus, P. I., Auerbach, D. I., Staiger, D. O., & Muench, U. (2013). Projections of the long-term growth of the registered nurse workforce: a regional analysis. Nursing Economics, 31(1), 13.;
  3. Buerhaus, P. I., Auerbach, D. I., & Staiger, D. O. (2014). The rapid growth of graduates from associate, baccalaureate, and graduate programs in nursing. Nursing Economics, 32(6), 290.;
  4. Buerhaus, P. I., Skinner, L. E., Auerbach, D. I., & Staiger, D. O. (2017). State of the Registered Nurse Workforce as a New Era of Health Reform Emerges. Nursing Economics, 35(5), 229-237.

[20] Massachusetts Department of Public Health. (2016). Data Brief: Health Professions Data Series – Registered Nurse 2014. Available from https://www.mass.gov/files/documents/2018/07/06/health-professions-data-series-registered-nurses-2014.pdf.

[21] See, for example:

  1. Estabrooks, C. A., Midodzi, W. K., Cummings, G. G., Ricker, K. L., & Giovannetti, P. (2005). The impact of hospital nursing characteristics on 30‐day mortality. Nursing Research, 54(2), 74-84.;
  2. Kane, R. L., Shamliyan, T. A., Mueller, C., Duval, S., & Wilt, T. J. (2007). The association of registered nurse staffing levels and patient outcomes: systematic review and meta-analysis. Medical Care, 45(12), 1195-1204.;
  3. Stalpers, D., de Brouwer, B. J., Kaljouw, M. J., & Schuurmans, M. J. (2015). Associations between characteristics of the nurse work environment and five nurse-sensitive patient outcomes in hospitals: a systematic review of literature. International Journal of Nursing Studies, 52(4), 817-835.

[22] Aiken, L. H., Cimiotti, J. P., Sloane, D. M., Smith, H. L., Flynn, L., & Neff, D. F. (2011). The effects of nurse staffing and nurse education on patient deaths in hospitals with different nurse work environments. Medical Care, 49(12), 1047.

[23] Djukic, M., Kovner, C. T., Brewer, C. S., Fatehi, F. K., & Cline, D. D. (2013). Work environment factors other than staffing associated with nurses’ ratings of patient care quality. Health Care Management Review, 38(2), 105-114.

[24] Griffiths, P., Ball, J., Drennan, J., Dall’Ora, C., Jones, J., Maruotti, A., ... & Simon, M. (2016). Nurse staffing and patient outcomes: Strengths and limitations of the evidence to inform policy and practice. A review and discussion paper based on evidence reviewed for the National Institute for Health and Care Excellence Safe Staffing guideline development. International Journal of Nursing Studies, 63, 213-225.

[25] Wallace, B. C. (2013). Nurse staffing and patient safety: What's your perspective?. Nursing Management, 44(6), 49-51.

[26] Boev, C., & Xia, Y. (2015). Nurse-physician collaboration and hospital-acquired infections in critical care. Critical Care Nurse, 35(2), 66-72.

[27] Dabney, B. W., & Kalisch, B. J. (2015). Nurse staffing levels and patient-reported missed nursing care. Journal of Nursing Care Quality, 30(4), 306-312.

[28] See, for example:

  1. Morey, J. C., Simon, R., Jay, G. D., Wears, R. L., Salisbury, M., Dukes, K. A., & Berns, S. D. (2002). Error reduction and performance improvement in the emergency department through formal teamwork training: evaluation results of the MedTeams project. Health Services Research, 37(6), 1553-1581.;
  2. Boyle, D. K., & Kochinda, C. (2004). Enhancing collaborative communication of nurse and physician leadership in two intensive care units. Journal of Nursing Administration, 34(2), 60-70.

[29] See, for example:

  1. Hertel, R. (2012). Regulating patient staffing: a complex issue. Academy of Medical-Surgical Nursing, 21(1), 3-7.; Douglas, K. (2010). Ratios-If it were only that easy. Nursing Economics, 28(2), 119.;
  2. Buerhaus, P. I. (2009). Avoiding mandatory hospital nurse staffing ratios: An economic commentary. Nursing Outlook, 57(2), 107-112.;
  3. Buerhaus, P. I. (2010). It's time to stop the regulation of hospital nurse staffing dead in its tracks. Nursing Economics, 28(2), 110.; Griffiths, P. (2009). RN+ RN= better care? What do we know about the association between the number of nurses and patient outcomes?. International Journal of Nursing Studies, 46(10), 1289-1290.;
  4. Sochalski, J., Konetzka, R. T., Zhu, J., & Volpp, K. (2008). Will mandated minimum nurse staffing ratios lead to better patient outcomes?. Medical Care, 46(6), 606-613.; Tevington, P. (2011). Mandatory nurse-patient ratios. Medsurg Nursing, 20(5), 265.;
  5. Wallace, B. C. (2013). Nurse staffing and patient safety: What's your perspective?. Nursing Management, 44(6), 49-51.;
  6. Welton, J. M. (2007). Mandatory hospital nurse to patient staffing ratios: Time to take a different approach. Online Journal of Issues in Nursing, 12(3).

[30] See, for example:

  1. Aiken, L. H., Sloane, D. M., Bruyneel, L., Van den Heede, K., Griffiths, P., Busse, R., ... & McHugh, M. D. (2014). Nurse staffing and education and hospital mortality in nine European countries: a retrospective observational study. The Lancet, 383(9931), 1824-1830.;
  2. Dall, T. M., Chen, Y. J., Seifert, R. F., Maddox, P. J., & Hogan, P. F. (2009). The economic value of professional nursing. Medical Care, 47(1), 97-104.;
  3. McHugh, M. D., Rochman, M. F., Sloane, D. M., Berg, R. A., Mancini, M. E., Nadkarni, V. M., ... & American Heart Association’s Get With The Guidelines-Resuscitation Investigators. (2016). Better nurse staffing and nurse work environments associated with increased survival of in-hospital cardiac arrest patients. Medical Care, 54(1), 74.

[31] Kane, R. L., Shamliyan, T. A., Mueller, C., Duval, S., & Wilt, T. J. (2007). The association of registered nurse staffing levels and patient outcomes: systematic review and meta-analysis. Medical Care, 45(12), 1195-1204.

[32] See, for example:

  1. Douglas, K. (2010). Ratios-If it were only that easy. Nursing Economics, 28(2), 119.;
  2. Buerhaus, P. I. (2009). Avoiding mandatory hospital nurse staffing ratios: An economic commentary. Nursing Outlook, 57(2), 107-112.;
  3. Buerhaus, P. I. (2010). It's time to stop the regulation of hospital nurse staffing dead in its tracks. Nursing Economics, 28(2), 110.;
  4. Griffiths, P. (2009). RN+ RN= better care? What do we know about the association between the number of nurses and patient outcomes?. International Journal of Nursing Studies, 46(10), 1289-1290.;
  5. Malloch, K. (2015). Measurement of nursing's complex health care work: evolution of the science for determining the required staffing for safe and effective patient care. Nursing Economics, 33(1), 20.

[33] Spetz, J. (2004). California's Minimum Nurse‐to‐Patient Ratios: The First Few Months. Journal of Nursing Administration, 34(12), 571-578.

[34]  Serratt, T. (2013). California’s Nurse-to-Patient Ratios, Part 3: Eight Years Later, What Do We Know About Patient Level Outcomes? Journal of Nursing Administration, 43(11), 581-585. Some of the individual primary studies included in this systematic review are:

  1. Burnes Bolton, L., Aydin, C. E., Donaldson, N., Storer Brown, D., Sandhu, M., Fridman, M., & Udin Aronow, H. (2007). Mandated nurse staffing ratios in California: a comparison of staffing and nursing-sensitive outcomes pre-and postregulation. Policy, Politics, & Nursing Practice, 8(4), 238-250.
  2. Donaldson, N., Bolton, L. B., Aydin, C., Brown, D., Elashoff, J. D., & Sandhu, M. (2005). Impact of California’s licensed nurse-patient ratios on unit-level nurse staffing and patient outcomes. Policy, Politics, & Nursing Practice, 6(3), 198-210.
  3. Cook, A., Gaynor, M., Stephens Jr, M., & Taylor, L. (2012). The effect of a hospital nurse staffing mandate on patient health outcomes: Evidence from California's minimum staffing regulation. Journal of Health Economics, 31(2), 340-348.
  4. Mark, B. A., Harless, D. W., Spetz, J., Reiter, K. L., & Pink, G. H. (2013). California's minimum nurse staffing legislation: results from a natural experiment. Health Services Research, 48(2pt1), 435-454.
  5. Hickey, P. A., Gauvreau, K., Jenkins, K., Fawcett, J., & Hayman, L. (2011). Statewide and national impact of California's staffing law on pediatric cardiac surgery outcomes. Journal of Nursing Administration, 41(5), 218-225.
  6. Donaldson, N., & Shapiro, S. (2010). Impact of California mandated acute care hospital nurse staffing ratios: A literature synthesis. Policy, Politics, & Nursing Practice, 11(3), 184-201.

[35] Health Policy Commission (2018). Mandated Nurse-to-Patient Staffing Ratios in Massachusetts: Research Presentation: Analysis of Potential Cost Impact. October 3, 2018.

[36]  Serratt, T. (2013). California’s Nurse-to-Patient Ratios, Part 3: Eight Years Later, What Do We Know About Patient Level Outcomes? Journal of Nursing Administration, 43(11), 581-585.

[37] See, for example:

  1. Chapman, S. A., Spetz, J., Seago, J. A., Kaiser, J., Dower, C., & Herrera, C. (2009). How have mandated nurse staffing ratios affected hospitals? Perspectives from California hospital leaders. Journal of Healthcare Management, 54(5), 321-335.;
  2. Weichenthal, L., & Hendey, G. W. (2011). The effect of mandatory nurse ratios on patient care in an emergency department. The Journal of Emergency Medicine, 40(1), 76-81.

[38] United States, & Centers for Medicare & Medicaid Services (U.S.). (2018). Hospital compare: A quality tool for adults, including people with Medicare. Washington, D.C: United States, Dept. of Health & Human Services. Data Accessed June 2018.

[39] Chapman, S. A., Spetz, J., Seago, J. A., Kaiser, J., Dower, C., & Herrera, C. (2009). How have mandated nurse staffing ratios affected hospitals? Perspectives from California hospital leaders. Journal of Healthcare Management, 54(5), 321-335.

[40] Auerbach, D. I., & Staiger, D. O. (2017). How fast will the registered nurse workforce grow through 2030? Projections in nine regions of the country. Nursing Outlook, 65(1), 116-122.

[41] McHugh, M. D., Brooks Carthon, M., Sloane, D. M., Wu, E., Kelly, L., & Aiken, L. H. (2012). Impact of nurse staffing mandates on safety‐net hospitals: Lessons from California. The Milbank Quarterly, 90(1), 160-186.

[42] Chapman, S. A., Spetz, J., Seago, J. A., Kaiser, J., Dower, C., & Herrera, C. (2009). How have mandated nurse staffing ratios affected hospitals? Perspectives from California hospital leaders. Journal of Healthcare Management, 54(5), 321-335.

[43] Reiter, K. L., Harless, D. W., Pink, G. H., Spetz, J., & Mark, B. (2011). The effect of minimum nurse staffing legislation on uncompensated care provided by California hospitals. Medical Care Research and Review, 68(3), 332-351.

[44] Chapman, S. A., Spetz, J., Seago, J. A., Kaiser, J., Dower, C., & Herrera, C. (2009). How have mandated nurse staffing ratios affected hospitals? Perspectives from California hospital leaders. Journal of Healthcare Management, 54(5), 321-335.

[45] Conway, P. H., Tamara Konetzka, R., Zhu, J., Volpp, K. G., & Sochalski, J. (2008). Nurse staffing ratios: trends and policy implications for hospitalists and the safety net. Journal of Hospital Medicine, 3(3), 193-199.

[46] Munnich, E. L. (2014). The labor market effects of California's minimum nurse staffing law. Health economics, 23(8), 935-950.

[47] McHugh, M. D., Brooks Carthon, M., Sloane, D. M., Wu, E., Kelly, L., & Aiken, L. H. (2012). Impact of nurse staffing mandates on safety‐net hospitals: Lessons from California. The Milbank Quarterly, 90(1), 160-186.

[48] Munnich, E. L. (2014). The labor market effects of California's minimum nurse staffing law. Health Economics23(8), 935-950.

[49] Munnich, E. L. (2014). The labor market effects of California's minimum nurse staffing law. Health Economics23(8), 935-950.

[50] Munnich, E. L. (2014). The labor market effects of California's minimum nurse staffing law. Health Economics, 23(8), 935-950.

[51]  Terasawa, E. (2016). California's minimum nurse-staffing law and its impact on hospital closure, service mix, and patient hospital choice. University of Pennsylvania. Doctoral Dissertation.

[52]  Terasawa, E. (2016). California's minimum nurse-staffing law and its impact on hospital closure, service mix, and patient hospital choice. University of Pennsylvania. Doctoral Dissertation.

[53] Massachusetts Nurses Association (2018). Research Linking Safe Patient Limits to Patient Safety. Accessed from https://www.massnurses.org/legislation-&-politics/safe-staffing/scientific-research.

[54] Buerhaus, P. I. (2010). It's time to stop the regulation of hospital nurse staffing dead in its tracks. Nursing Economics, 28(2), 110.

[55] Mark, B. A., Hughes, L. C., & Jones, C. B. (2004). The role of theory in improving patient safety and quality health care. Nursing Outlook, 52(1), 11-16.

[56] Stone, P. W., Tourangeau, A. E., Duffield, C. M., Hughes, F., Jones, C. B., O'Brien-Pallas, L., & Shamian, J. (2003). Evidence of nurse working conditions: a global perspective. Policy, Politics, & Nursing Practice, 4(2), 120-130.

[57] Spetz, J., Harless, D. W., Herrera, C. N., & Mark, B. A. (2013). Using minimum nurse staffing regulations to measure the relationship between nursing and hospital quality of care. Medical Care Research and Review, 70(4), 380-399.

[58] Spetz, J., Harless, D. W., Herrera, C. N., & Mark, B. A. (2013). Using minimum nurse staffing regulations to measure the relationship between nursing and hospital quality of care. Medical Care Research and Review, 70(4), 380-399. Clarke, S. P., & Donaldson, N. E. (2008). Nurse staffing and patient care quality and safety. An excerpt from Patient Safety and Quality: An Evidence-Based Handbook for Nurses.

[59] Seago, J. A. (2002). The California experiment: alternatives for minimum nurse-to-patient ratios. Journal of Nursing Administration, 32(1), 48-58.

[60] Kane, R. L., Shamliyan, T. A., Mueller, C., Duval, S., & Wilt, T. J. (2007). The association of registered nurse staffing levels and patient outcomes: systematic review and meta-analysis. Medical Care, 45(12), 1195-1204.

[61] Sochalski, J., Konetzka, R. T., Zhu, J., & Volpp, K. (2008). Will mandated minimum nurse staffing ratios lead to better patient outcomes?. Medical Care, 46(6), 606-613.

[62] McHugh, M. D., Brooks Carthon, M., Sloane, D. M., Wu, E., Kelly, L., & Aiken, L. H. (2012). Impact of nurse staffing mandates on safety‐net hospitals: Lessons from California. The Milbank Quarterly, 90(1), 160-186.

[63] Seago, J. A., Williamson, A., & Atwood, C. (2006). Longitudinal analyses of nurse staffing and patient outcomes: more about failure to rescue. Journal of Nursing Administration36(1), 13-21.

[64] Aiken, L. H., Clarke, S. P., Sloane, D. M., Sochalski, J., & Silber, J. H. (2002). Hospital nurse staffing and patient mortality, nurse burnout, and job dissatisfaction. Journal of the American Medical Association, 288(16), 1987-1993.

[65] Jackson, M., Chiarello, L. A., Gaynes, R. P., & Gerberding, J. L. (2002). Nurse staffing and health care-associated infections: Proceedings from a working group meeting. American Journal of Infection Control, 30(4), 199-206.

[66] Page, A. (Ed.). (2004). Keeping patients safe: Transforming the work environment of nurses. National Academies Press.

[67] See, for example:

  1. Shindul-Rothschild, J., Flanagan, J., Stamp, K. D., & Read, C. Y. (2017). Beyond the pain scale: provider communication and staffing predictive of patients’ satisfaction with pain control. Pain Management Nursing18(6), 401-409.
  2. Read, C. Y., Shindul-Rothschild, J., Flanagan, J., & Stamp, K. D. (2018). Factors Associated With Removal of Urinary Catheters After Surgery. Journal of Nursing Care Quality33(1), 29-37.
  3. Shindul-Rothschild, J., Read, C. Y., Stamp, K. D., & Flanagan, J. (2017). Nurse staffing and hospital characteristics predictive of time to diagnostic evaluation for patients in the emergency department. Journal of Emergency Nursing43(2), 138-144.

[68] Stamp, K. D., Flanagan, J., Gregas, M., & Shindul-Rothschild, J. (2014). Predictors of excess heart failure readmissions: implications for nursing practice. Journal of Nursing Care Quality29(2), 115-123.

[69] Shindul-Rothschild, J., Flanagan, J., Stamp, K. D., & Read, C. Y. (2017). Beyond the pain scale: provider communication and staffing predictive of patients’ satisfaction with pain control. Pain Management Nursing, 18(6), 401-409.

[70] Stamp, K. D., Flanagan, J., Gregas, M., & Shindul-Rothschild, J. (2014). Predictors of excess heart failure readmissions: implications for nursing practice. Journal of Nursing Care Quality29(2), 115-123.

[71] Shindul-Rothschild, J., Read, C. Y., Stamp, K. D., & Flanagan, J. (2017). Nurse staffing and hospital characteristics predictive of time to diagnostic evaluation for patients in the emergency department. Journal of Emergency Nursing43(2), 138-144.

[72] Clarke, S. P., & Donaldson, N. E. (2008). Nurse staffing and patient care quality and safety. An excerpt from Patient Safety and Quality: An Evidence-Based Handbook for Nurses.