A law setting mandatory nurse-to-patient staffing ratios has reduced the number of workplace injuries for registered nurses and licensed practical nurses in California, according to recently published findings.

The state law enacted in 2004 established minimum staffing ratios for acute care hospitals, and is the only such law in the United States. It can be credited with a 32% average yearly reduction in registered nurse illnesses and injuries, investigators at the University of California, Davis determined. There also have been a third fewer injuries for licensed practical nurses.

Studies linking the law to patient outcomes have arrived at mixed results, the study authors noted.

“Our study links the ratios to something just as important — the lower workers’ compensation costs, improved job satisfaction and increased safety that comes with linking essential nursing staff levels to patient volumes,” lead author J. Paul Leigh, Ph.D., stated in a press release.

The increased staffing could prevent injuries in a number of ways, Leigh noted. For instance, having multiple people to transfer a patient could reduce back and shoulder injuries.

The findings stemmed from an analysis of injury and illness rates tracked by the U.S. Bureau of Labor Statistics. The BLS routinely identifies nursing as one of the most dangerous professions in the country, and nursing homes as especially hazardous settings due to the propensity for staff to lift residents without mechanical assistance.

Leigh and his colleagues believe their research could support similar staffing laws in other states. Many providers have expressed wariness about these laws, due to increased costs and the inconclusive findings regarding patient outcomes.

Full findings have been published in the online version of the International Archives of Occupational and Environmental Health.