A 2004 California law mandating specific nurse-to-patient staffing standards in acute care hospitals has significantly lowered job-related injuries and illnesses for both registered nurses and licensed practical nurses, researchers report.

The need for higher nurse-to-patient ratios is typically invoked as a patient safety issue, and research supports that claim. Studies have found an increased risk of patient infections, mortality, and worker burnout as the number of patients assigned a given nurse increases. For example, a study that analyzed survey data from more than 7,000 registered nurses from 161 hospitals in Pennsylvania linked nurse understaffing to burnout and increased rates of catheter-associated urinary tract infections and surgical site infections.1 Another study found that every additional patient assigned to a nurse over four resulted in a 7% increase in mortality for all patients under that nurse’s care.”2

That said, there is not a clear consensus that the California law has improved patient outcomes, which was its primary intent. However, the recently published study is believed to be the first to evaluate the effect of the California staffing law on health care workers.3

The researchers estimated that the California law has resulted in an average annual reduction from 176 injuries and illnesses per 10,000 registered nurses to 120 per 10,000 — a 32% cut. For licensed practical nurses, the average yearly change went from 244 injuries per 10,000 to 161 per 10,000 — a 34% reduction.

“We were surprised to discover such a large reduction in injuries — these findings should contribute to the national debate about enacting similar laws in other states,” says lead author J. Paul Leigh, PhD, a professor of public health sciences at the Center for Healthcare Policy and Research at UC Davis in Sacramento.

California is the only state in the country with mandated minimum nurse-to-patient ratios, though other states have enacted requirements for staffing committees or public disclosure of staffing levels. California’s mandated nurse-to-patient ratios include:

  • intensive care units 1:2:
  • labor/delivery 1:3
  • pediatrics 1:4
  • medical–surgical 1:5
  • psychiatric 1:6

According to Leigh, some hospitals have argued against extending the law to other states because of the increased costs of additional nursing staff.

“Our study links the ratios to something just as important — the lower workers’ compensation costs, improved job satisfaction and increased safety,” he says.

Using data from the U.S. Bureau of Labor Statistics, Leigh and colleagues compared occupational illness and injury rates for nurses during several years before and after implementation of the new law. The change in injury rates among hospital nurses after implementation of the law in California was compared to the change in 49 other states and Washington, D.C. combined. This “difference-in-differences” methods separated the effects of California’s staffing mandates, though only for a few years after it was enacted.

Leigh speculated that the lower rates of injuries and illnesses to nurses could come about in a number of ways as a result of improved staffing ratios. Back and shoulder injuries could be prevented, for instance, if more nurses are available to help with repositioning patients in bed. Likewise, fewer needle-stick injuries may occur if nurses conduct blood draws and other procedures in a less time-pressured manner. The investigators recommended additional research using more recent data to see if the reductions in injury and illness rates held up over time.

“Even if the improvement was a temporary or ‘halo’ effect of the new law, it is important to consider our results in debates about enacting similar laws in other states,” he says. “Nurses are the most recognizable faces of health care. Making their jobs safer should be a priority.”

The research findings should embolden ongoing efforts to enact “safer” nurse-patient ratio laws in other states.

“The staffing problem in our hospitals has gotten worse lately,” says Kathy Santoiemma, RN, a nurse at Montefiore Medical Center’s New Rochelle (NY) Hospital. “The hospital practice of understaffing is almost a daily problem for us and it must be addressed.”

Santoiemma was one of some 1,000 members of the New York State Nurses Association (NYSNA), who recently rallied at the state capitol in Albany to support a proposed state law that would mandate “safe” nurse-patient ratios to protect patients from falls, healthcare-associated infections (HAIs) and other adverse events. Of course, protecting nurses is part of the equation, but the NYSNA has primarily seized on the political clout of patient safety in lobbying for the law.

“Staffing is an issue across the board, not just for our nurses but for our patients,” says Tara Martin, senior communications manager for the NYSNA. “The primary function of a nurse is to be an advocate for the patients. When you’re understaffed you have a problem because you are not giving your full attention to every patient that needs it. So it creates an unsafe work environment for the nurses and also [endangers] patients. Our primary focus has always been to make sure our patients are safe. With the current staffing levels that are happening across the state, patients are definitely at risk.”

The Safe Staffing for Quality Care Act would set enforceable nurse-to-patient ratios in New York health care facilities. The law would require minimum staffing levels ranging from one nurse per patient in trauma emergency, per two patients in ICUs, per three patients in the emergency department, per four patients on medical\surgical wards and per five patients in rehab\subacute. The bill has passed one committee, but must go through another committee to reach the floor for a full vote. “We actually have momentum on this bill and we hope to have a vote by the end of the session, which is in June,” Martin says.

The nurses cite clinical studies that have consistently shown that safe staffing improves patient outcomes and even saves money.

“In study after study, unsafe staffing levels lead to worse health outcomes, including shock, cardiac arrest, and hospital-acquired pneumonia,” says Martha Wilcox, an RN at Sullivan County (NY) Public Health. “We know that a safe and reliable healthcare system of the future cannot be created unless we empower our frontline providers of care, and give them what they need to get the job done. We need hospital management to take safe staffing seriously.”

However, hospital associations and other groups are arguing against such laws, saying they need staffing flexibility and mandated nursing levels could undermine their economic stability and cause cuts in other areas. The Greater New York Hospital Association (GNYHA) warned that staffing mandates will force hospitals to lay off other members of the care team and close nursing units because of a shortage of appropriately trained nursing staff. The nurses risk making their situation worse by “draining the resources necessary to provide support staff, licensed practical nurses, nurse assistants, and other types of professional staff, including physical therapists, clinical pharmacists, and phlebotomists,” the GNYHA said, adding that the extra work would then fall to nurses.


  1. Cimiotti JP, Aiken LH, Sloane DM, et al. Nurse staffing, burnout, and health care associated infection. AJIC 2012;40:486-490.
  2. Aiken, LH, Clark SP, Sloane DM, et al. Hospital Staffing and patient mortality, nurse burnout and job dissatisfaction. JAMA 2002; 288:16:1987-1993
  3. Leigh JP, Markis CA, Losif AM, et al. California’s nurse-to-patient ratio law and occupational injury. Int Arch Occup Environ Health 2015; 88(4):477-484