About The Gazette Search Back Issues Contact Us    
The newspaper of The Johns Hopkins University August 6, 2007 | Vol. 36 No. 41
It's Time to Look at Health Risks in a New Light, Authors Say

Environmental scientists Edward Bouwer and Erik Rifkin used their expertise analyzing data to help the average reader better assess common health risks.
Photo by Will Kirk/HIPS

Researchers believe many patients get incomplete view of med test benefits

By Phil Sneiderman Homewood

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 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.

Their findings are described in The Illusion of Certainty: Health Benefits and Risks, published by Springer. 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. A chapter called "The Physician's and Patient's Perspective" was 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.

"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 uncertainly 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 who received a medication and one who did not. If one person among 100 people who took medication died, the death rate would be 1 percent. If two people died among 100 people who did not take medication, the 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.

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 vs. two) died in the group who 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 risks 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."

The authors 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."


The Gazette | The Johns Hopkins University | Suite 540 | 901 S. Bond St. | Baltimore, MD 21231 | 443-287-9900 |