Proportionately more H1N1 patients needed ICU care compared with seasonal flu patients. (CBC)

H1N1 patients were younger, sicker, and a higher proportion of them died compared with seasonal flu patients, according to a new Canadian report.

Thursday's analysis by the Canadian Institute for Health Information (CIHI) is the first pan-Canadian look at how hospitalizations for H1N1 differed from hospitalizations for a typical flu.

Public health officials mounted an unprecedented response to the H1N1 pandemic. Now that it is winding down in Canada, the researchers aimed to document lessons for the future.

Analysts compared FluWatch data from the Public Health Agency of Canada from April to December 2009 with CIHI's hospital statistics for the year 2007 to 2008.

Among the 8,507 people hospitalized for H1N1 during the study period, the median age of patients was 28 compared with 71 during a regular flu season.

Hospital care in H1N1

"I think it sort of shows the magnitude of the difference," said Kathleen Morris, head of emerging issues at CIHI. "So we know they're younger. We also have a better sense of how they used hospital care."

Proportionately more H1N1 patients needed specialized and intensive hospital care like ventilation and admission to the intensive care unit than in a typical flu season, said Jean-Marie Berthelot, vice-president of programs at CIHI.

During the 2007 flu season, seven per cent of those admitted to hospital with influenza or pneumonia were admitted to an intensive care unit. For H1N1, almost 17 per cent of hospitalized H1N1 patients were admitted to ICU, the researchers found.

Of those who were hospitalized with regular flu, three per cent were put on mechanical ventilation. For hospitalized H1N1 patients, the need for ventilation more than tripled to 10 per cent.

Of the in-hospital deaths, 1.6 per cent occurred for seasonal flu compared with five per cent for H1N1.

There were also four deaths of pregnant women with H1N1, but deaths in hospital among pregnant women with seasonal flu was "exceedingly rare," the report's authors found.

"Those are small numbers but I think there are some signs that it's worth continuing to look into the effects of H1N1 on pregnancy," Morris said.

Factors including the virus itself and those related to the patient could explain why H1N1 killed more pregnant women or made them seriously ill. The researchers hope their work will be springboard into answering those questions.