Aiken's most famous projects involve studies that link lower patient-to-nurse staffing ratios with better outcomes.
In 2002, Aiken's research revealed that every time another general surgical patient is added to a nurse's workload, there's a 7% higher mortality rate for the patients, and the nurses have more burnout and job dissatisfaction.
And in 2010, she found that if Pennsylvania and New Jersey, two states with no patient-nurse ratio legislation, staffed hospitals at the levels mandated by California's nurse staffing mandate, implemented in 2004, in-hospital mortality for patients undergoing common surgical procedures would drop between 10.6% and 13.9%.
The California law says one nurse should care for no more than five patients on a medical-surgical unit, two in the intensive care unit, and three in a labor and delivery unit.
When lawsuits threatened the 1999 California law, nursing organizations successfully used Aiken's 2002 research as a defense before the state Supreme Court.
Hospitals started to pay more attention to the issue.
"Now we have a patient-nurse ratio bill pending in Pennsylvania, and many other states have legislation under consideration," she says. Half of all states either have some other form of nurse staffing legislation passed or in the works, she says.
Aiken doesn't pin her success on passage of laws, however, but on the public debate they provoke. "We've changed the way a broad group of stakeholders thinks about nursing, that it is a resource to contribute to better patient care, as compared to just a flat-out operating cost, which is how hospital executives often think about it," she says.