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News Release

Office of News and Information
Johns Hopkins University
901 South Bond Street, Suite 540
Baltimore, Maryland 21231
Phone: 443-287-9960 | Fax: 443-287-9920

August 6, 2007
CONTACT: Phil Sneiderman

It's Time to Look at Health Risks
in a New Light, Authors Say

Researchers Believe Many Patients Get Incomplete View
of Medical Test Benefits

How solid is the link between high cholesterol and heart disease? Do regular screening tests for breast and prostate cancer lead to far fewer deaths from these diseases? How safe is the water we drink and the air we breathe? How should we interpret the daily flood of news reports on sometimes contradictory medical studies?

A new book, co-written by a Johns Hopkins University professor and an outside colleague, seeks to examine health questions like these in a new light. Authors Erik Rifkin and Edward Bouwer are not physicians; both are environmental scientists with decades of experience in analyzing health risks connected with air, water and soil pollution. By directing this expertise at data from mainstream medical studies, the researchers believe they have found a fresh way to help the average reader assess common health risks.

Edward Bouwer and erik
Environmental scientists Edward Bouwer and Erik Rifkin used their expertise in data analysis to help the average reader better assess common health risks
Photo by Will Kirk

Their findings are described in a new book published by Springer and titled The Illusion of Certainty: Health Benefits and Risks. Bouwer is a professor and chair of the Department of Geography and Environmental Engineering at Johns Hopkins. Rifkin is president of an environmental consulting firm in Baltimore. The book includes a chapter on "The Physician's and Patient's Perspective," written by Bob Sheff, a radiologist who trained at UCLA and Johns Hopkins.

The researchers said they wrote the book because they believe that the average person, who must make critical decisions about health risks, is not getting a complete picture. They discovered that health-related choices that sometimes sound straightforward and obvious are often much more uncertain and controversial when the risk statistics are viewed in a different way.
Edward Bouwer
Edward Bouwer
Photo by Will Kirk

"I've been involved in human health and environmental risk assessment for more than 30 years," Rifkin said. "It became clear to me during this time that the uncertainty in health risk assessment had gotten lost, and the numbers had taken on a life of their own."

He had collaborated with Bouwer on projects for 20 years, and the two decided to train their science skills on data from medical studies. "I can read scientific articles, and I've had experience handling epidemiological data," Bouwer said. "You can look at the data in medical studies the same way you look at environmental data. We did, and we found that there was a lot of uncertainty in these studies, but it often wasn't being communicated to people."

Much of this misinformation, the researchers said, comes from the way risks are explained to a patient or described in a news story. One measure, called absolute risk reduction, looks at the difference in death rates between two groups, such as one group that received a medication and one that did not. If one person died among 100 people who took medication, the death rate would be 1 percent. If two people died among 100 people who did not take medication, that death rate for that group would be 2 percent. The difference between these death rates, found by subtracting 1 percent from 2 percent, would yield the absolute risk reduction: 1 percentage point.
Erik Rifkin
Erik Rifkin
Photo by Will Kirk

But the authors learned that drug companies, journalists and some medical professionals often rely on a different measure: relative risk reduction. This term compares only the raw numbers of people who died in each instance. In the above example, because half as many people (one versus two) died in the group that took the medication, the relative risk reduction is 50 percent. By this measure, the patient can be told that his or her chance of dying is cut in half by taking the drug, instead of being told that there was only a 1 percentage point difference in the treated group.

"It's as if, in hearing about a baseball game between the Orioles and the Yankees, you're told that the Orioles scored twice as many runs as the Yankees," Rifkin said. "But if you don't know the actual numbers involved, you don't know whether this was a close 2-1 game or a 20-10 rout. If you don't know where you're starting from, the relative risk figures will not be helpful."

In their book, Bouwer and Rifkin argue that, although relative risk is a useful yardstick for research scientists, "it should not be used by the public to assess the risks and benefits of screening tests. Far more weight should be given to absolute risk reduction values."

In their book, Rifkin and Bouwer give readers an easy way to visualize the absolute risk numbers through a graphic called the Risk Characterization Theater. This diagram is patterned after a seating chart for a theater with space for 1,000 people. The authors darken the "seats" that represent the number of people who are likely to benefit from a screening test or a medication or who may be at increased risk from exposure to an environmental contaminant.

"These theater charts make it easier for people to see what the case studies are referring to," Bouwer said. "We're trying to give people some new tools to help them make better informed decisions about health risks."

Various chapters in the book focus on topics such as environmental contaminants, prostate screening, cholesterol, statin drugs, smoking, chlorinated drinking water and exposure to residential radon. The authors said their intent is not to offer medical advice but to show readers another way to evaluate health risks.

In the book's foreword, Jared L. Cohon, president of Carnegie Mellon University, says Rifkin and Bouwer have been "courageous in writing this book. In going to the heart of what's been lacking in risk communications and management, they have taken on established thinking. As a result, this book may be controversial. In my view, a book like this is long overdue, and we all will be better for the reflection and debate it is likely to stimulate among scientists and policy-makers."

Journalists who wish to interview the authors or request a review copy of the book may contact Phil Sneiderman at 443-287-9960 or prs@jhu.edu.

Digital photos of Bouwer and Rifkin available; contact Phil Sneiderman.

Related Links
arrow Baltimore Sun article on The Illusion of Certainty (free registration required at Sun site)
arrow Johns Hopkins Department of Geography and Environmental Engineering

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