Sheetz - former director of school health services at the Massachusetts Department of Public Health - said the findings were of particular interest in Philadelphia, where last week a first grader died after becoming ill at a school that had no full-time nurse.
Jackson Elementary student Sebastian Gerena, 7, died of a congenital heart defect. It is unclear whether a full-time nurse at the school would have made a difference.
The study, published this month, examined a Massachusetts program that put full-time nurses in schools. Using data collected in those schools, researchers calculated how much nurses' procedures would have cost at a hospital or clinic, and measured the cost of lost workplace productivity by parents and teachers.
They found that during the 2009-10 school year, nurses at 933 schools were paid $79 million. The care they provided would have cost $20 million elsewhere, the researchers calculated, plus $28 million in parent productivity losses and $129.1 million in teacher productivity losses.
Sheetz said that many decision-makers do not realize the far-reaching effects that nurses have in schools, especially urban ones.
"They really are one of the most cost-effective, unrecognized resources in our country," she said.
Philadelphia school nurse Eileen DiFranco has long made the authors' point.
"Cutting nurses is not a savings," said DiFranco, who is Roxborough High School's nurse. In late 2011 and early 2012, she organized a series of protests outside Philadelphia School District headquarters after 47 nurses lost their jobs for budgetary reasons.
The district's money woes have worsened, and nurse staffing has paid the price.
"911 gets called for nosebleeds, for stitches, for things that are not a medical emergency," DiFranco said. "People do not have the expertise to be able to parse out an emergency for something that's not run-of-the-mill."
Just Tuesday, DiFranco handled crises small and big, including dealing with one student who had been sexually assaulted and another who had overdosed on medication.
DiFranco works full time at Roxborough because it's a larger school - 618 students - with many teens who have special medical needs, she said.
At Jackson Elementary, two adults - including a retired nurse who happened to be volunteering at the school - administered CPR on the boy until emergency crews arrived. District officials say all protocol was followed.
"But that's no plan," DiFranco said. "That's just dumb luck."
After the boy's death, Superintendent William R. Hite Jr. was careful to praise the adults who tended to Sebastian Gerena.
But Hite, in a statement after the death, also said the Jackson student's case "illustrates the serious needs and challenges that our students, teachers, staff and principals face every day. During times of tragedy, our community should not have to question whether an extra staff member or program would have made a difference. We should all feel confident that our schools have everything they need."
About 45 percent of U.S. public schools have full-time nurses; 30 percent have a part-time nurse; and 25 percent have no nurse.
Michael Pistiner, a Massachusetts pediatric allergist who worked with the school health program there, hopes the study has far-reaching implications.
"This should change our conversations," Pistiner said. "This should change the way school boards look at the way money spent on nurses is considered."