Young Canadians at high risk for H1N1
October 12, 2009
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EMILY MATHIEU
STAFF REPORTER
Canadians in their 30s are most susceptible to contracting H1N1, and once admitted to hospital require rapid admittance to critical care and aggressive treatment, according to a new study.
"In the Canadian context we found these were young patients, much younger than we would usually imagine treating flu patients in the ICU," said Dr. Robert Fowler, a critical care physician at Sunnybrook hospital.
The report, Critically Ill Patients With 2009 Influenza A(H1N1) Infection in Canada, included treatment information for 168 critical care patients in Canada infected with H1N1 from April to June of this year. Also released was Critically Ill Patients with 2009 Influenza A(H1N1) in Mexico, a joint effort between critical care specialists in Canada and Mexico. Fowler was the senior author on both studies, published Monday in the Journal of the American Medical Association.
He said the two most "surprising," results in the Canadian study were the relatively low age of patients and the number of patients who required aggressive treatment, including ventilation, signalling the need to properly prepare for the second wave this fall.
"Our absolute numbers of patients who are going to need support in ICU is going to be a lot more than people are used to seeing and that is the thing people are trying to plan for," said Fowler. "I would say the ability to treat patients early and then through the illness with a very aggressive supporting care can save lives."
The mean age of patients was about 32. About 67 per cent, or 113 cases, were female; children accounted for 29 per cent, or 50 cases, and aboriginal Canadians were 25 per cent, or 43 cases.
In the Canadian report, the authors described the high numbers of females who became seriously ill as "striking," as "female susceptibility has not been observed in other influenza outbreaks.
The report goes on to state the "explanation for increased risk of severe disease and death among females in this report is unclear, but the role of pregnancy as a risk factor has been noted in previous influenza pandemics."
Patients were admitted to hospital four days after their symptoms appeared and patients requiring critical care were admitted to the ICU about 24 hours later, with 81 per cent receiving ventilation the first day.
Of the 168 critically ill patients, 29 died, the majority in two weeks.
The majority of the deaths were female, or 72 per cent and four of the deaths were children. While young people are the most susceptible to contracting H1N1 – potentially because of lack of exposure to previous strains of influenza – the study showed seniors, in their 70s and 80s, were the most likely to die after contracting H1N1.
Fowler said mortality rates among patients in Mexico was double that, partly because of increased patient volumes preventing the same speed of admittance to the ICU and varying methods of treatment.
He said early therapy, involving anti-viral medication and aggressive therapy in critical care kept the mortality rate in Canada low.
There is some concern that capacity in some reasons could be stretched during peak season, he said.
Hospitals, particularly critical care wards, operate close to or at capacity all the time, said Fowler. "So in order to get more capacity you need to be very flexible and this opens up the idea of sharing resources across jurisdictions that we have never had to do or think about before."
The province is planning to purchase extra equipment for critical care treatment.
Allison Stuart, assistant deputy minister of public health for the Ministry of Health and Long-Term Care, said the province is currently reviewing proposals from ventilator manufacturers, with the intent of purchasing approximately 200 ventilators for more aggressive treatment, including intubation.
It's important to have the proper equipment, she added, but you still need the appropriate staff to treat and monitor critically ill patients.
She said most facilities will have ventilators in different areas of the hospitals and the individuals who support that equipment may be able to be reassigned to the critical care unit. "That will allow for some limited surge capacity," she said.
thestar.com