WASHINGTON: Taking an aspirin every day may help prevent heart disease and stroke but, for a middle-aged man, it is nearly as risky as driving a car or working as a firefighter, researchers said on Tuesday.

While people are poor at assessing true risks, they are often willing to take on those risks in exchange for the benefits - which can include simply having fun, said Joshua Cohen and Peter Neumann of Tufts-New England Medical Center.

Writing in the journal Health Affairs, they said federal regulators must take the true risks into account, and balance them against the benefits, when deciding whether to approve or withdraw drugs.

People are bad at estimating risk, the researchers said. "In general, they tend to overestimate the probability of small and especially dreaded risks while underestimating the probability of large risks," Cohen and Neumann wrote. They calculated the risks of various voluntary actions, starting with deaths associated with taking drugs. "We included selected drugs for which we could develop a reasonable annual mortality risk estimate," they wrote.

For 50-year-old men, taking an aspirin every day to prevent heart disease and stroke carries a risk of 10.4 deaths per 100,000 men per year over and above their overall death risk. Using Vioxx for arthritis pain carried a risk of 76 deaths per 100,000 people per year. Merck and Co withdrew Vioxx in September 2004 after it was shown to double the risk of heart attack and stroke.

"The finding that taking Vioxx for a year is much more risky than a year of car travel, swimming or being a firefighter suggests that greater scrutiny of drug risks may be warranted," the experts wrote.

Using Tysabri, known generically as natalizumab, to treat multiple sclerosis raises the death rate by 65 per 100,000 people a year.

Biogen Idec's and Elan Corp's Tysabri was withdrawn from the US market last year after three patients contracted a rare brain disease, but the FDA is reconsidering it after many patients said they would use it despite the risks. As for job-related deaths, the riskiest profession was being a tree-feller, with 55 deaths per year or a risk of 357 deaths per 100,000 people a year.