TORONTO - Developing countries with limited access to advanced health-care facilities may be in for a rough ride with swine flu and even countries with high-tech ICUs may find themselves pushed to the limit as their hospitals struggle to save gravely ill H1N1 patients, new studies suggest.
The studies, which compare outcomes among H1N1 patients admitted to intensive care units in Canada and Mexico, showed the death rate in the latter was more than double that seen among Canadian patients. Just over 40 per cent of critically ill Mexican patients succumbed to their illness by day 60, compared to 17.3 per cent of Canadian patients by day 90.
"I think this H1N1 (virus), it's not going to be the one that people would say 'Oh, my God, that killed off X per cent of our population'," said Dr. Rob Fowler, a critical care specialist and senior author of both studies.
"But we're going to see large numbers of patients that have illness, a subset that are critically ill and in different parts of the world it's actually going to translate into lots of people dying that wouldn't have otherwise died - especially so if you can't support them (medically)."
The studies were published online Monday by the Journal of the American Medical Association. Their publication was timed to coincide with Fowler's presentation of the data at a conference staged by the European Society of Critical Care Medicine.
Dr. Michael Osterholm, an infectious diseases expert at the University of Minnesota, said the findings should serve as an eye-opener for the large segment of the public that has dismissed swine flu as a mild form of influenza.
For many it is, but "for a very small number of patients, this illness is hell," said Osterholm, director of the Center for Infectious Diseases Research and Policy.
An editorial that accompanied the package said saving that group of patients depends on the ability of medical teams to employ sophisticated mechanical ventilatory support. There may not be enough of these beds available or the trained staff needed to deliver this kind of care, the authors warned.
"Clinicians and hospitals should take note that the rescue therapies used in these studies have the potential to cause harm if not implemented in a co-ordinated manner," noted Dr. Douglas White and Dr. Derek Angus, critical care physicians at the University of Pittsburgh.
They suggested hospitals need to make plans for how they will handle an influx of severely ill cases, noting that while the number of such cases during the spring wave was modest, the burden they place on hospitals in both Canada and Mexico was "sobering."
"Any deaths from 2009 influenza A (H1N1) will be regrettable, but those that result from insufficient planning and inadequate preparation will be especially tragic," Angus and White said.
As they and many others have noted, this pandemic is not triggering the volume of severe disease experts feared the world might see with the first pandemic of the century.
While it's not currently possible to estimate what percentage of people who catch the virus need to be hospitalized, it is clear that for most people, H1N1 is indistinguishable from regular influenza.
But a small proportion of patients became profoundly ill and did so quickly. Fowler said those who went into this sharp decline generally ended up in the ICU within about 24 hours of entering hospital.
There medical teams battled to save their lives, hooking these patients up to ventilators that breathed for them or even the types of bypass machines - called extracorporeal membrane oxygenation, or ECMO - used in cardiac surgery.
These patients are far younger than those hospitals generally see dying from flu or the complications of flu, said Dr. Anand Kumar, an intensivist who treated many of these patients in Winnipeg hospitals this spring and the lead author on the Canadian study.
He said any loss of life in an ICU is difficult, but it is especially hard when the cases are like those this virus often kills - younger adults and middle-aged people who were relatively healthy before they contracted the virus.
"To lose somebody 24, 25, 30, 40 years old - it's just not their time," Kumar said.
He said he's gotten emails from intensivists all over asking why public health authorities are calling this flu mild, "because it's certainly not mild from an ICU context." The World Health Organization also objects to the use of the term mild to describe this pandemic, calling it moderate.
Where resource-intensive therapies are available, chances are decent that H1N1 patients will pull through, these and other recently published studies have found.
But where they are not, the death toll will be higher, said Fowler, a critical care specialist at Toronto's Sunnybrook Health Sciences Centre.
"This is a young, relatively healthy group of patients that has their lungs fail. And if you can throw the book at them to get their lungs through this, then you have a pretty good shot at keeping them alive," Fowler said.
"And I think in places that aren't able to do that, well ... you have a much lesser likelihood of making it."
The comparison of the outcomes between the two patient groups - 168 confirmed or probable cases in Canada, 58 in Mexico - provided some other important information.
Fewer of the patients from Mexico were treated with antiviral drugs like Tamiflu, allowing the authors to compare the outcomes of the patients who received the drugs and those who did not.
Antiviral treatment is recommended for all patients sick enough to require hospitalization, even if treatment is commenced later than the 48-hour window in which therapy is supposed to start for best results. In Canada most of the patients would have received the drugs, so there would be no way to assess whether they were helping or not.
But by comparing the data from the two countries, the authors showed that people who received the drugs were seven times more likely to survive than those who did not.
"People should get these drugs," Fowler said.
The Canadian study also found a disproportionately high percentage of the severely ill cases were women - 67.3 per cent. The virus is especially tough on pregnant women, but the pregnancy doesn't account for all of the excess in women, Fowler said.
He admitted the gender imbalance among severe cases is puzzling.
"I have no idea why that could be the case," Fowler said. "But that does seem to be something that has been consistently reported ... that critically ill women are over-represented relative to critically ill men."
Follow Medical Reporter Helen Branswell's flu coverage on Twitter at CP-Branswell.