Swine Flu Study Finds Women More at Risk: Females and Aboriginals Linked to Critical Cases of H1N1 Influenza

The United States, Mexico, Canada, Chile, and Australia have documented the largest number of confirmed cases of H1N1 flu, which is also known as swine flu. Both Canada and Mexico have dealt with big localized H1N1 outbreaks, where people have become seriously ill and had to be taken to the intensive care unit (ICU) for ventilator support. This Canadian study is called, and takes a closer look at, Critically Ill Patients with 2009 Influenza A (H1N1) Infection in Canada.

Patients Involved in Canadian H1N1 Flu Study

The research took place between April 16 and July 13, 2009 and involved 168 critically ill patients with confirmed or probable H1N1 influenza infections in Canada.

The average age was 32 for those who were critically ill and it included:

  • 70% were adults
  • 67% were women
  • 40% were Caucasian
  • 25.6% were First Nations, Metis, Inuit or Aboriginal
  • 10% were Asian or Latin American (includes South Asian and West Asian/Arab)
  • 8% were Black

Most Common Symptoms of Critically Ill H1N1 Patients

More than 90 per cent of these patients had a fever and respiratory problems. More than half were experiencing weakness and more than a third had muscle pain or tenderness. (more on this on www.optinghealth.com)

Other conditions people had with the H1N1 infection included possible bacterial pneumonia in almost a third of cases and extremely low blood pressure in 13.7 per cent of cases. Other medical problems that small number of patients had at the same time as the H1N1 virus include either asthma, chronic pulmonary disease, an altered level of consciousness, a serious kidney injury, or chest pain.

How Long Patients were Patients Sick With H1N1 Flu?

Patients who were seriously ill exhibited symptoms for about four days before they went to the hospital. Once they were in the hospital, most of them ended up in the ICU within a day. The majority of critically ill patients had extensive fluid buildup in their chest and a serious lung injury during the onset of their infection. Very few, just six per cent of them, had had a seasonal flu shot in the past two years.

More than three-quarters of these patients had to be put on a ventilator on their first day in the ICU, with only a third of them having the procedure done noninvasively. But, most of those who had the noninvasive procedure initially, ended up needing invasive ventilation later on. The average stay on ICU was 12 days, which is also the average time that patients were on a mechanical ventilator.

Deaths Due to the H1N1 Flu

Twenty-nine people died out of the 168, with 18 passing away within the first two weeks and six more died within the two week period after that. Of those who died, 21 were female and eight were male. There were 50 children who were critically ill, four of them died. There were also nine health care workers, and none of them died.

Research Finds Women and Aboriginal Patients More at Risk for Severe Case of H1N1 Flu

Young women and aboriginal patients who didn’t have any preexisting medical conditions were the ones most affected in the spring outbreak of the H1N1 flu. The study found that once people became critically ill, many of them had trouble breathing and needed to be put on a ventilator. Rescue therapies also needed to be administered multiple times.

Researchers found it “striking” that women were more likely to develop a severe case of H1N1 flu. Females being more at risk has not been seen in other flu studies. When it comes to most infectious diseases and related complications like septic shock, men usually are more at risk for getting sick and dying. Scientists don’t know why women are more at risk, but they do say that pregnancy has put women at higher risk when analyzing data from past flu pandemics.

Weakness of Canadian Study of Swine Flu

Researchers say that critically ill H1N1 cases were studied from across Canada, but there was a sizeable outbreak in the province of Manitoba. Many of the cases came from an aboriginal community in Manitoba and this could impact the figures when trying to generalize to the larger population.

Strength of Canadian H1N1 Flu Study

This study is the largest of its kind to look at a series of patients with severe cases of the 2009 H1N1 influenza. It also included both adults and children from different races and geographical areas from across Canada, making the results more applicable to the general population.

Importance of Hospital Care for Critically Ill H1N1 Patients

The researchers say for most critically ill H1N1 patients, going on a ventilator and rescue therapies can help people survive this illness. But, with a second wave of this virus set to spread this winter, no one knows exactly how many people will get sick. This is an important issue, because it could impact a hospital’s ability to provide the critical care that is needed for those with severe cases of the swine flu to survive.