In a review of data from 168 Pennsylvania hospitals, surgery patients' death rates were nearly twice as high when the percentage of nurses with bachelor's degrees was low, University of Pennsylvania researchers said.
Low levels of education, coupled with low nurse staffing levels, could translate to thousands of preventable deaths nationwide each year, the researchers said.
The findings suggest that recruiting nurses with four-year bachelor's degrees instead of just two or three years of education "may lead to substantial improvements in quality of care," they said.
Registered nurse degrees are offered by two-year community colleges, three-year hospital diploma programs and four-year bachelor's of science programs.
Better-educated nurses tend to be more proficient in critical thinking, said lead author Linda Aiken, a University of Pennsylvania nursing and sociology professor.
"In most university programs, nurses are being reared alongside of physicians in medical schools and so they have the opportunity early in their education to interact with physicians and develop those skills that are ever important in critical circumstances," she said.
The percentages of more highly educated nurses vary at hospitals nationwide and ranged from zero to 77 percent at the hospitals studied.
The patients studied underwent common operations, such as knee replacements, appendectomies and gallbladder removal. Hospitals with fewer than 10 percent of nurses with bachelor's degrees had death rates of nearly 3 percent for such patients, compared with a 1.5 percent death rate at hospitals where more than 70 percent of nurses had bachelor's degrees.
"Some 4 million procedures like the ones we studied are performed in U.S. hospitals every year, yielding a substantial number of preventable deaths," Aiken said.
The findings appear in Wednesday's Journal of the American Medical Association.
Previously published research by the same group found that patient survival rates are also directly related to nurse staffing levels.
The current study found that nurse education is critically important as well, even when other factors that also affect death rates are taken into account, like surgeon expertise, severity of patients' conditions and availability of technology.
In Pennsylvania alone, low nurse education and low staffing levels may contribute to at least 1,700 preventable deaths annually, the researchers said.
The results were challenged by the National Association for Associate Degree Nursing, which represents community colleges offering two-year nursing programs.
"The conclusions are not supported by the data and there are serious questions about the flawed methodology," the group's president, Sharon Bernier, said in a statement.
Bernier said there is no difference in competence between associate- and bachelor's degree nurses. She faulted the study for lumping bachelor's degree nurses with those who obtained master's degrees or higher.
Nationwide data from 2001 show that 61 percent of new registered nurses came from associate-degree programs, 36 percent from bachelor's degree programs and 3 percent from hospital diploma programs - which educated the bulk of U.S. nurses 50 years ago.
The trend has continued to increase in favor of bachelor's degree programs, said Patricia Grady, director of the National Institute of Nursing Research, which helped fund the research.
The demands of modern-day nursing require a more educated nurse work force because hospitalized patients tend to be sicker and treatments more complex, Grady said.
By Lindsey Tanner