The figure is still only an estimate. The final death rate will be known only when the epidemic is over. Also, the estimate is for those diagnosed with SARS, not necessarily everyone infected with the SARS virus. Including such people would lower the death rate.
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2003 JUN 8 - (NewsRx.com & NewsRx.net) -- The overall death rate from SARS worldwide is about 15% - double previous estimates - according to the first in-depth global analysis by the World Health Organization (WHO).
Officials at the U.N. health agency said the calculation indicates the disease is more dangerous, particularly in the elderly, than experts had thought. More than half of SARS patients over 65 are dying.
Until now, WHO had estimated the death rate to be between 6% and 10%. The new estimate was based on more complete and detailed data from China, Canada, Hong Kong, Singapore and Vietnam.
A new study estimated the death rate in Hong Kong to be about 20% overall, but about 50% in patients over 60.
"The global estimate we had previously was always clearly an underestimate," said Mike Ryan, who is coordinating SARS response at the World Health Organization.
"We always had a figure in our heads that was a range, but now we see that it's toward the upper end of that range. We didn't have a proper estimate and this is now much more accurate," he said.
Severe acute respiratory syndrome has made more than 7,000 people around the world ill and killed more than 500.
Until now, WHO has been making a crude calculation of the death rate by dividing the number of deaths by the number of SARS cases. Using that method, the death rate would be 7.1%, which underestimates the true death rate because it assumes everyone still hospitalized will survive.
Another method is to add up the number of people who have died and those who have recovered and divide the deaths into that total. However, that overestimates the death rate because deaths show up more quickly than recoveries and it ignores people who are hospitalized, Ryan said.
The new figure was reached by estimating what proportion of those hospitalized will recover and what proportion will die. It also takes into account the length of time patients have survived - looking at the risk of dying in the first week of illness, the risk in the second week, and so on.
However, the figure is still only an estimate. The final death rate will be known only when the epidemic is over. Also, the estimate is for those diagnosed with SARS, not necessarily everyone infected with the SARS virus. Including such people would lower the death rate.
As suspected, the analysis indicated the chances of dying from SARS greatly depend on age and, linked to that, on the existence of other illnesses, Ryan added.
The death rate is below 1% for people aged 24 or younger, rising to 6% for those 25-44, 15% in those aged 45-64 and more than 50% for those over 65, WHO estimates.
"You really have to take into account the age groups because that will determine the outcome," Ryan said. "Some countries, like Canada, appear to have a high case fatality. In fact, that's more determined by the fact that their patient group was older.
"In Vietnam, their fatality rate was 8%. That's probably determined less by the quality of care but more by the fact that the majority of those cases were in young, healthy adults," he said.
By contrast, WHO said the death rate was 14% in Singapore and 15% in Hong Kong. The agency did not give a rate for China or Canada.
WHO experts said there is no evidence the SARS virus is becoming more lethal.
Recent fears that about 12 people in Hong Kong had relapsed after being sent home from the hospital have turned out to be unfounded, said Dr. David Heyman, the agency's communicable diseases chief.
"SARS has not reoccurred in any of these patients. These patients have been readmitted to hospital, but with diseases other than SARS," he said.
WHOsaid it was still optimistic it could prevent SARS from taking root in communities, even in China, where the number of reported cases continues to rise.
The number of new cases is now coming into single digits in Singapore, Hong Kong and Canada, Heymann noted.
China may be reporting more cases every day because it is now starting to look more actively for them, Heymann said.
"It's not just enough to look and say China continues to increase in the number of cases reported every day. What you must know is the date of onset of those cases, which is the information we are working with the Chinese government to obtain."
This article was prepared by Medical Letter on the CDC & FDA editors from staff and other reports.
