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Vioxx, Tsunami Present the Puzzle of Risk 2005-01-06
Vioxx, Tsunami Present the Puzzle of Risk
January 6, 2005; Page A2
About 1 in 200 people who took Vioxx in one study had a heart attack versus 1 in 1,000 for people taking naproxen. In another, there were about 1 in 29 heart attacks or strokes among those taking Vioxx versus 1 in 52 for those taking a placebo. The pill was pulled from the market. That risk was deemed too big to take. History suggests that the risk of a tsunami in the Indian Ocean is extremely small. Yet the catastrophic consequences of that once-every-century-or-so event are now evident.
Did we overreact to the Vioxx risk? Did we underprepare for tsunami risk. If so, why? Despite the advance of science, education and communication, understanding and responding wisely to risks -- particularly small ones -- turns out to be very tough.
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Perhaps it's because such worrying is a relatively recent luxury in human evolution. "Human beings would not have survived in the dangerous circumstances of the ancestral environment had they been prone to let their attention wander from situations fraught with a high probability of immediate death, as when being attacked by a predator ... to low-probability menaces -- which anyway they couldn't have done much about," federal appeals-court Judge Richard Posner writes in his new (and extraordinarily well-timed) book, "Catastrophe."
"It is not surprising that evolution didn't produce an ability to think clearly about such [small] risks as a standard part of our mental skill set," he suggests.
Getting the facts straight is crucial, of course. Experts often disagree. A 1987 New Yorker cartoon by Mischa Richter shows one professorial-looking man at a bar saying to another: "Then we've agreed that all the evidence isn't in, and that even if all the evidence were in, it still wouldn't be definitive." Even when experts agree, facts sometimes are presented so incompletely that even educated consumers are puzzled.
But publicizing properly qualified, expert-certified facts is far from sufficient, and that's where this gets interesting and difficult. Psychological research shows a statement made one way can be reassuring, but frightening if made in a different, yet mathematically equivalent, way. People react more to 1-in-100 risk than to a 1% risk, though the two are identical. "If I say, '1 in 100,' people imagine the numerator. Who is the one? There's more of a feeling of reality," says psychologist Paul Slovic, president of Decision Research, a Eugene, Ore., risk-research outfit.
WHAT ARE THE ODDS?
Odds of winning
Power Ball lottery 1 in 120,526,770
Odds of heart attack or stroke
…on Vioxx 1 in 29
…on placebo 1 in 52
Lifetime odds of dying
…as pedestrian 1 in 608
…in fire 1 in 1,116
…in swimming pool 1 in 6,196
…in bathtub 1 in 11,469
Odds of on-job injury
…in iron foundries 1 in 6
…in coal mines 1 in 16
…among couriers 1 in 36
…in gas stations 1 in 59
Sources: CT Lottery, Merck, National Safety Council, Bureau of Labor
Arnold Barnett, a Massachusetts Institute of Technology aviation professor, once made an observation he meant to be reassuring: "If you go into Logan airport here in Boston and you buy a lottery ticket on the way to catch your plane, you're more likely to win the lottery than perish on the flight." It backfired. People enjoy thinking the odds of winning the lottery are better than they actually are. And they don't like juxtaposing their best hopes with their worse fears. His more successful alternative: "If you took one jet flight a day every day, you go 33,000 years before succumbing in a fatal crash."
Still, why do so many people persist in accepting some large risks (shunning seat belts or motorcycle helmets) while fretting about smaller ones (avoiding Celebrex or artificial sweeteners)? Sometimes, it's warped self-perception. "Most people," says Baruch Fischhoff, a Carnegie Mellon University psychologist, "think of themselves as safer than average drivers." Sometimes, it's a feeling of helplessness. "People dislike small risk if they think others are imposing it on them," such as a hazardous-waste dump in the neighborhood, he says. Sometimes, it's just dread. Says Dr. Slovic: "Dying in an airplane crash seems more dreadful than dying in a car crash. Heart disease is dreaded less than cancer."
The human mind assesses risk in two very different ways, it turns out. One is analytical, which is susceptible to science, probability tables and the like. But the other is what Dr. Slovic calls "the gut feelings and instinctual reactions that reside within us, a carry-over from our long evolutionary development from the time when we didn't have scientific rational analysis and had to use our instincts." The latter is very powerful, but too often ignored in well-intentioned efforts to get people to comprehend small risks and act accordingly, both as individual consumers and as citizens.
After Chernobyl, Love Canal and anxiety about AIDS in the blood supply,
a panel formed by the National Academy of Science published a thoughtful
report in 1989 called, "Improving Risk Communication." It had
a long list of recommendations, most aimed at federal agencies. What happened?
"Not much," says John Ahearne of Sigma Xi, a scientific-research
society, who was the chairman of the panel. Why? "People in and out
of government said it looked awfully hard to do."