WOULD MANDATED NURSE staffing ratios improve patient outcomes in Massachusetts? And are there even enough nurses to fill new slots that such a requirement would create?

It’s little wonder that voters are having a hard time sorting out these issues: A group of nursing experts differed sharply on the questions during a panel discussion convened on Wednesday by the state Health Policy Commission.

Massachusetts voters will be asked in a November ballot question whether the state should mandate minimum nurse staffing levels in hospitals. The Massachusetts Nurses Association, the state’s leading nurses’ union, which worked to put the measure on the ballot, says it will improve patient safety and care. The state’s hospitals, the main force opposing the question, say it will cause a spike in health care costs with no clear benefit to patients.

Judith Shindul-Rothschild, a professor of nursing at Boston College who authored an analysis of the ballot question impact for the Massachusetts Nurses Association, told the Health Policy Commission the evidence supporting increased nurse staffing was clear. “It is indisputable that better RN staffing levels lead to better patient outcomes,” said Shindul-Rothschild, a former president of the Mass. Nurses Association.

But Joanne Spetz, a professor at the University of California, San Francisco, said it is not clear that a law mandating minimum nurse staffing levels would lead to better patient outcomes. Spetz has extensively studied the issue in California, the only state with required nurse staffing minimums, and said the evidence there is far from clear-cut.

Vicki Bermudez, a regulation policy specialist at the California Nurses Association, told the commission that a study of California and two other states after the law was in place suggested those states would have seen 10 to 14 percent fewer surgical deaths had they adopted nurse staffing ratios similar to California’s.

Spetz said implementation of the California law in 2004 has increased nurse staffing levels there, but she said there is no firm evidence of a causal link between those changes and improved patient outcomes. She said that was even true in analyses that looked only at California hospitals that had the widest patient-to-nurse ratios before the law. “You didn’t see changes in outcomes that aligned with what you’d expect from the changes in staffing,” she said following the panel discussion.

Spetz coauthored a recent report with the Health Policy Commission’s research director, David Auerbach, that examined the cost implications of the Massachusetts ballot question. Their analysis, released earlier this month, projected that the measure would increase health care costs in Massachusetts by $676 million to $949 million and require the hiring of 2,286 to 3,101 new nurses.

The law would require different minimum nurse staffing levels depending on the patients being cared for. On standard hospital floors, a nurse could be responsible for no more than four patients. For most emergency department patients or on units caring for more acutely ill patients, the ratios would be smaller.

One major issue of disagreement among the panelists was whether an adequate supply of nurses exists to meet increased staffing demands if the question passes.

Nancy Gaden, the chief nursing officer at Boston Medical Center, said her hospital already struggles to fill nursing positions, a situation that she said would become much worse if the ballot question is approved.

“I am alarmed at what would happen if Question 1 passed and what it would mean for the delivery of care at my hospital, and at all hospitals across Massachusetts,” she said.

She said the staffing mandates would require her hire 52 new emergency department nurses, 20 new labor and delivery nurses, and 92 new nurses on medical and surgical floors. Until those staffing levels are reached, she said, the hospital would be turning away up to 100 people a day in its emergency department, the busiest in the state, and would have to close a third of its labor and delivery beds.

Shindul-Rothschild scoffed at the idea of nursing shortage, saying nursing students are desperate to be hired in the state. “I can tell you, because I am the faculty advisor for the Massachusetts Student Nurse Association, they are having a very hard time getting jobs in Massachusetts,” she said. “We don’t have a nursing shortage.

One explanation for the starkly different picture, said some on the panel, is a skills mismatch between the training of nursing graduates and the types of positions that hospitals need to fill.

The disagreement over the state’s nursing supply spilled over into differing views on the likely impact of the ballot question on nursing salaries. The analysis prepared by Spetz and Auerbach estimated that nursing salaries would increase by 4 to 6 percent if the ballot measure passes. But Shindul-Rothschild said the estimate was too high given the ample supply of nurses.

There was not even agreement on when the mandated staffing levels would take effect if voters approve the measure. The ballot question says the new law would be effective January 1, 2019, less than two months after the November 6 election.

Gaden said it will be impossible to hire enough new nurses in that time frame. “To be absolutely honest with you, if this passes, what I will focus on during November and December is closing areas so that I can meet the law,” she said.

Eliminating services because of an inability to meet staffing requirements, or the potential closure of entire smaller, community hospitals because of the cost of the hiring mandates, are among the potential harmful consequences opponents of the ballot question have cited.

But Shindul-Rothschild said the mandates would not take effect until each hospital develops a plan approved by the Health Policy Commission. She also pointed out that mandates don’t take effect in hospitals where nurses have union contracts until those agreements expire.

Tim Foley, a member of the commission and vice president of 1199SEIU Healthcare Workers East, said it was hard to sort out the competing claims on nursing supply and likely wage impact of the ballot question.

“There’s two different opinion on that. We’ve heard very different stories,” he said. “So I can understand why voters right now are very confused in Massachusetts.”

Stuart Altman, the commission chairman, said he’s had lots of conversations with people who readily admit to that confusion. “I can’t tell you the number of people who came to me, who legitimately wanted to do the right thing and said, ‘We have no idea [how to vote],’” he said. “‘Why are you asking voters to make this kind of a complicated decision?’”