WASHINGTON (Reuters) - People who use statin drugs are less likely to die of influenza and chronic bronchitis, according to a study that shows yet another unexpected benefit of the cholesterol-lowering medications.

Their study of more than 76,000 people showed that those who had taken statins for at least 90 days had a much lower risk of dying from chronic obstructive pulmonary disease or COPD, the technical name for emphysema and chronic bronchitis.

Patients on statins also had a lower risk of dying from influenza or pneumonia, the researchers reported on Monday.

Statins -- which include Pfizer Inc.’s $10 billion-a-year Lipitor, Bristol-Myers Squibb Co.’s Pravachol and Merck and Co. Inc.’s Zocor -- are the world’s best-selling drugs, taken by millions to reduce the risk of heart attack.

The new study supports a theory proposed last year that statin drugs might help patients with H5N1 avian influenza, which some studies suggest kills by causing an immune system overreaction called a cytokine storm.

Floyd Frost of the Lovelace Respiratory Research Institute in Albuquerque, New Mexico and colleagues analyzed their institute’s database of medical records from several health maintenance organizations.

They looked at incidence of influenza and pneumonia and of COPD, and then cross-checked to see which patients were also taking statins.

“This study found a dramatically reduced risk of death from COPD among statin users and a significantly reduced risk of death from influenza/pneumonia,” the researchers wrote in their report, published in the journal Chest.

“These findings suggest that moderate-dose statin use reduces the risk of influenza/pneumonia death and strongly suggest that statins reduce the risk of COPD death.”

In 2006, researchers in Canada reported that statins act against sepsis, a dangerous blood infection, and a 2005 study found the death rate was 64 percent lower in pneumonia patients who had been taking statins.

BUYING TIME?

Experts say a pandemic of some sort of influenza is inevitable.

The H5N1 avian influenza sweeping countries in Asia and also affecting Europe and Africa is considered the most likely candidate. So far it has rarely infected people, but has killed 170 people out of 285 known to have been infected.

Experts generally agree that an effective vaccine would take months to formulate and perhaps years to make enough doses to cover the world. There is also a shortage of antiviral drugs.

Statins might buy some time, Frost’s team wrote.

“Even if statins are not able to significantly reduce the risk of death from avian influenza, their use could significantly extend the time between disease onset and death,” they wrote.

“This additional survival time could increase the effectiveness of anti-influenza drugs, providing a longer time to reduce mortality risks.”

Last July, Dr. David Fedson, a retired corporate expert on vaccination, cited studies that suggested statins might calm down immune response. The drugs are known to affect the insides of blood vessels, but their full mechanism of action is not fully understood.