MIT economist Jonathan Gruber and Samuel Kleiner of Cornell University analyzed 50 strikes in New York between 1983 and 2004. They calculated that mortality rose to 2.22 percent on average during strikes, compared to 1.86 percent in the periods before and after the job actions — a 19.4 percent jump. Readmissions increased by an average of 6.5 percent, according to their 2010 paper.

One of the few studies examining this question found that more patients die and are readmitted to the hospital during nurses’ strikes.

Tufts Medical Center has gone to great lengths to reassure patients during this week’s strike by nurses, but there is some evidence that medical care can suffer when nurses walk the picket line.


“We found consistent evidence that patient outcomes worsened,’’ Gruber said in an interview.

The authors did not determine the reason for the increase, and Gruber cautioned that the results do not mean that patient care suffers during every strike. But he said one possible factor is that replacement nurses hired from temp agencies may be less experienced than staff nurses.

Tufts executives said they do not believe Gruber’s study applies to their hospital. Dr. Saul Weingart, chief medical officer, pointed out that most of the hospitals the economists examined were smaller than Tufts, and may not have overnight coverage from attending physicians, residents, and fellows. Weingart also said most of the strikes lasted far longer, some for weeks — though Gruber said he also saw problems during week-long job actions.

“Tufts Medical Center is known for great clinical care and a welcoming atmosphere. This will not change,” Weingart said.

Hospital spokeswoman Brooke Tyson Hynessaid executives carefully selected replacement nurses to make sure their experience matches patients’ needs. Tufts said it hired the nurses through US Nursing Corp. and that they have experience working at academic medical centers providing complex care.


“Anyone in the NICU [neonatal intensive care unit] has NICU experience. Anyone on the cardiac floor has cardiac experience,’’ Hynes said.

The 1,200 Tufts nurses went on strike for one day, but the hospital said it will lock them out for an additional four days, meaning they can return to work Monday.

The hospital and the nurses union provided very different accounts of the first day of the strike. Weingart said care at the hospital was “pretty seamless.’’ The union, the Massachusetts Nurses Association, said members had received texts from employees inside the hospital reporting chaos.

“What we’ve heard is that it’s very chaotic, and people don’t know what they’re doing,” said Barbara Tiller, a Tufts nurse for 27 years who was protesting outside the hospital on Wednesday. “They’re trying to do a job that they’re not trained to do, and it’s scary.”

For example, union officials said the hospital’s chief nursing officer walked into the cardiac transplant unit and asked if there were any nurses with transplant experience. One nurse posted on Facebook that a replacement nurse from Louisiana failed an NICU medication administration test twice and was sent home.

Hynes said she could not verify the account about the transplant unit, but that it would not be unusual for managers to ask nurses about their experience when they are handing out assignments in the morning. She said the anecdote about the Louisiana nurse was untrue.

Ultimately, state health inspectors will determine whether the strike is affecting patient care.


Six officials from the Department of Public Health arrived at Tufts at 6 a.m. Wednesday and stayed until noon, hospital executives said. Inspectors plan to return twice a day at unannounced times until the nurses return to work. The Department of Mental Health is also onsite.

Tom Lyons, a spokesman for the Department of Public Health, said “some minor issues were identified and quickly corrected’’ on Wednesday. “The hospital was very responsive to our observations and requests. Throughout the coming days, we will continue to work with the medical center to ensure patients receive safe, effective, and high-quality care,’’ he said in an e-mail.

The department required Tufts to submit a comprehensive strike plan that included staffing details, but it would not release the plan to the Globe.

Anecdotally, there have been safety problems during nurses strikes around the country.

A replacement nurse working during a strike at Abbott Northwestern Hospital in Minnesota severely injured an asthmatic patient by administering adrenaline in a way that contradicted a doctor’s order, the Star Tribune in Minneapolis reported in October, citing a federal Medicare investigation.

In Worcester, three replacement nurses were fired during a 2000 strike at Worcester Medical Center, now called Saint Vincent Hospital, for poor patient care. State and hospital officials said at the time that two were terminated after leaving a patient unattended for nearly an hour following surgery, while another was fired for handing the wrong baby to a mother to breast-feed.


In many cases, said Charles Idelson, spokesman for National Nurses United, the country’s largest union and professional association for registered nurses, hospitals will postpone elective surgeries, transfer unstable patients to other facilities, and seek the help of nurse managers, who are licensed and unaffiliated with the union.

However, Tufts officials have indicated that the hospital would be operating as usual during the strike, with all appointments and surgeries continuing as scheduled, unless patients are informed otherwise. “That is totally irresponsible,” said Idelson.

Hynes said the hospital absolutely has acted responsibly.

“The MNA made the decision to strike, and they set the date for nurses to leave our patients. Tufts Medical Center did the responsible thing. We brought in talented, experienced nurses to pick up where our nurses left off,” she said in an email.

Liz Kowalczyk can be reached at kowalczyk@globe.com.