Swine Flu’s Surge in Intensive Lung Cases Reveals Winter’s Toll

By Tom Randall

Oct. 9 (Bloomberg) -- Swine flu drove a 15-fold increase in intensive care admissions for viral lung inflammation in Australia and New Zealand, especially among pregnant women, the obese and people with chronic lung disease, a study found.

During the peak of severe illness, patients with the new H1N1 influenza strain filled 8.9 percent to 19 percent of all intensive-care hospital beds in each state of Australia and New Zealand, according to the study published yesterday in the New England Journal of Medicine. Almost 65 percent of intensive-care H1N1 patients required mechanical ventilation.

The Southern Hemisphere’s winter flu season, studied from June 1 to Aug. 31, may give health officials in the Northern Hemisphere an indication of what to expect in coming months, the researchers said yesterday. The pandemic filled all available beds in some units and prompted doctors to postpone nonessential surgery, New Zealand’s health ministry said in July.

“We were being hit hard by young people with severe influenza pneumonitis, which we don’t normally see,” said Ian Seppelt, an intensive care specialist at Sydney’s Nepean Hospital and one of the study’s authors, in a telephone interview today.

The study, by doctors from the Australian and New Zealand Intensive Care Society, identified 856 patients with type-A influenza who were admitted to intensive care units, including 722 with laboratory-confirmed swine flu. That compares with an average of 57 patients admitted with viral pneumonitis, or lung inflammation, in the previous four years.

“The 2009 H1N1 virus had a substantial effect,” the doctors said. “Our data indicate that the greatest effect on ICU resources in a given region occurs approximately 5 to 6 weeks after the first confirmed winter admission,”

Spreading Virus

H1N1 rates have subsided in the Southern Hemisphere, and the virus is now spreading widely in most U.S. states, according to the U.S. Centers for Disease Control and Prevention. The official winter flu season started in the U.S. on Oct. 4, and doctors began administering vaccines this week in the country’s largest flu vaccination program.

Patients most at risk for severe complications in the study included infants, adults ages 26 to 64, pregnant women, the obese, and indigenous populations, according to the researchers. More than 16 percent of patients admitted to hospitals died, and a third of severely ill people had no underlying condition that would elevate their risk, according to the study.

Pregnant women, who make up 1 percent of the population in the two countries, were responsible for 9.1 percent of the intensive-care cases. Obese patients with body mass index over 35 were responsible for 29 percent of admissions, even though they only made up 5.3 percent of the population in 2003. People with asthma and other chronic lung conditions made up 33 percent of the severe cases and just 13 percent of the population.

U.S. Cases

In a separate study in the journal, the CDC studied 272 patients hospitalized in the U.S. for at least 24 hours from April, when the disease first emerged, to mid-June. About 75 percent of the patients took antiviral therapies, including Roche Holding AG’s Tamiflu and GlaxoSmithKline Plc’s Relenza.

Among the U.S. cases, 25 percent were admitted to an intensive care unit and 7 percent died. About 73 percent were pregnant or had underlying conditions including asthma, diabetes, heart, lung and neurologic diseases.

To contact the reporters on this story: Tom Randall in New York at trandall6@bloomberg.net
Last Updated: October 8, 2009 22:42 EDT