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SARS lesson: Beware the undiagnosed case

HCWs dominate discussion, but 39 patients died

One of the harsh lessons of the "unforgiving" outbreak of severe acute respiratory syndrome (SARS) in Toronto was the infectious risk of the undiagnosed patient. While much has been made of the respiratory protection issues and fit-testing of N95 respirators, almost three-quarters of the health care workers infected in the 2003 Toronto outbreak were treating patients who had not been diagnosed with the emerging infection, said Allison McGeer, MD, infectious disease consultant at Mount Sinai Hospital in Toronto.

Speaking at a recent Institute of Medicine (IOM) meeting on personal protective equipment (PPE) issues raised by pandemic flu, McGeer said hazard identification was the single greatest protective factor for health care workers.

"The hazard analysis has to be right; we have to identify people who need to be in precautions," she told the IOM. "During the SARS outbreak, the rate of infection when patients were not recognized as SARS patients was 2.2 health care workers per patient day. When they were recognized as SARS patients — no matter when during the outbreak, no matter what people were wearing, no matter whether [respirators] were fit-tested — the rate was 0.0034 infections per patient. As with every other infectious disease, the critical issue is hazard identification — not what you wear afterwards."

Some noncompliance found

According to an analysis by McGeer and colleagues, another 12% of health care workers were infected because they were not adherent to precautions while treating SARS patients. Sometimes the patients were not identified with SARS, but that was in the stage of the outbreak when PPE had been ordered to treat all patients with respiratory conditions.

"They were supposed to be using precautions for people who had any kind of respiratory infection, but they made a conscious decision [that] the patient didn't have SARS and did not comply with precautions," she said. "And in a couple of circumstances patients were recognized with SARS, but it was early in the outbreak and the health care workers just didn't get the message about the severity and potential risk and didn't use precautions."

15% infected while using PPE

That leaves 15% of health care workers infected while they were "taking care of people with SARS and more or less using the right precautions," McGeer said. "Those 15% are the proportion where either we are talking about better adherence to precautions mitigating infection or we are talking about better design of PPE mitigating infection. This tells you why it is so hard to get data on what kind of PPE people should be wearing and what a good design is. Because you are only talking about being able to modify 15%; the other 85% are other issues entirely."

The final report by the Ontario Commission to Investigate the Introduction and Spread of SARS criticized some ICPs and medical officials about the lack of fit-testing programs for N95 respirators and for not urging rigorous airborne precautions from the onset of the emerging infection, even though the report itself acknowledges that "the jury is still out on the extent of airborne SARS [transmission]."

While lamenting the outcome, McGeer emphasized that many clinicians were concerned about the impact of ubiquitous PPE use on patient care. "Some say the health care industry is like other industries, but there are two kinds of people in the health care system," McGeer said. "Some of them are health care workers, but the rest of them are patients. I would point out to you that there were three health care workers who died of SARS in Toronto and that was catastrophic. But there were 39 patients who died, and they had even less choice about where they were and what happened to them during the SARS outbreak. In doing research on protecting health care workers in hospitals, we need to explicitly identify the impact of them on patients, and make sure when we are making workplaces safe for health care workers we are also making them safe for patients. Sometimes, those issues are in conflict."

McGeer presented data at the IOM meeting on PPE adherence (i.e., masks, eye protection, gloves) collected in interviews with some 800 health care workers who treated SARS patients at different Toronto hospitals. The investigation used a questionnaire, and patient charts were available to remind workers what happened. The outbreak was declared on March 15 and was declared over in mid-June.

"By the time we get into April, precautions were ordered for all patients with respiratory disease, so now you should see [full PPE] adherence was 100% for everybody," she said.

But compliance with PPE was falling short, running only 80% even for patients with known SARS. "By the time you get to May, six or seven weeks into the outbreak, adherence is about 95%," McGeer says. "The point is this was very scary. Health care workers were extremely worried about their own health. There was blanket media coverage and public health units and every health care facility in the city were doing their level best to get information to health care workers and try to make sure that everyone was wearing PPE. But six weeks into the outbreak they weren't doing that. We had enormous trouble getting people to change their behavior for what was clearly a life-threatening illness."

Paradoxically, lack of PPE adherence was found in health care workers treating some of the sickest patients. "The sicker the patient, the less likely people were to be adherent to precautions," McGeer said. "And we think that is probably a 'hero' phenomenon. People were less likely to wear precautions because they perceived it was interfering with care of patients that really needed them."

In general, workers in SARS units and ICUs were more compliant, suggesting training and education were a factor. "We had an enormous amount of difficulty changing people's behavior in an acute setting when the incentive to change should have been large," she says. "We think that health care workers were making decisions sometimes for their patients rather than themselves."