Getting the most out of a medical study
Every day, millions of Americans are bombarded with health information through drug ads on TV. Millions more go online to research a new diagnosis, search for treatments or simply cruise websites devoted to health.
In the month of September alone, 51.9 million Americans -- or 33 percent of all people who use the Web -- visited health-related websites, according to ComScore Media Matrix, a research firm based in Reston, Va., that tracks Web use.
The trouble is, much of the information thrown at us on TV or offered up on the Web is misleading or downright wrong. Even reliable-looking research can be less meaningful than it appears. How can you tell the difference between credible information and half-truths? Here are 10 tips:
1. When cruising the Web, take the time to notice who wrote what you're reading. It's easy to just keep clicking on links and find yourself sliding from a reputable site, like the one on cancer run by the federal government (www.nci.nih.gov), to sites run by pharmaceutical companies or advocacy groups with their own agendas. A group called the Health on the Net Foundation (www.hon.ch) scrutinizes sites for accuracy and offers a seal of approval.
2. Check the attribution of any medical article you stumble upon. Usually, the most reliable studies are those published in an authoritative medical journal such as the Journal of the American Medical Association (http://jama.ama-assn.org) or the New England Journal of Medicine (www.nejm.org), or whose articles have been reviewed by experts. While you're at it, look to see who funded the study: The company that makes the drug has a stake in the results.
3. Get a sense of how powerful a study is and exactly what questions it's attempting to answer. Some studies only involve a handful of people, others many thousands -- making their results more definitive. Some studies are "observational," meaning that doctors track what happens to patients taking a certain drug or practicing a certain behavior. Such studies are not as strong as "randomized, controlled, double-blind clinical trials," in which patients are chosen by chance to get, say, a new drug or a placebo, and neither they nor their doctors know at the outset who is in which group.
4. Pay attention to how much benefit patients really got. A new cancer drug may extend life, but it's important to know if it works for two months or two years.
5. Make a distinction between the chances of getting a disease and dying from it. The oft-cited, and true, figure that one in eight women will get breast cancer over a lifetime is very scary. Certainly, no one wants to be diagnosed with cancer, but only one in four women who gets breast cancer actually dies of it, said Dr. Eric Winer, director of the breast oncology center at the Dana-Farber Cancer Institute.
6. Watch for what health outcome is being measured. Some studies look at "intermediate outcomes," such as drugs that lower triglycerides, which are risk factors for developing heart disease, but not evidence of the disease itself. Be wary of studies that lump together several outcomes, what researchers called "combined end points." One ad touting the cholesterol-lowering drug Lipitor says it lowers the rate of fatal and nonfatal heart attacks by 36 percent. But the fine print says the reduction in fatal heart attacks, taken separately, was not statistically significant, which means it could have been due to chance, said Dr. Lisa Schwartz and Dr. Steven Woloshin of the the Veterans Administration Outcomes Group and Dartmouth Medical School.
7. Be on the lookout for apples-to-oranges comparisons. The five-year survival rate makes it look as though there's been a huge decline in prostate cancer deaths over the last 30 years. In 1974, 33 percent of all men diagnosed with the disease died within five years; from 1995 to 2000, fewer than 1 percent of those diagnosed died. But the actual mortality rate barely budged over that time. The reason the five-year survival rate is so impressive is that we're catching prostate cancer much earlier now, so men are living longer with the knowledge that they have the disease.
8. Before dumping prescriptions or changing behavior, make sure to understand how big the risk really is. Many doctors and postmenopausal women may have overreacted two years ago when a link was found between hormone replacement therapy and breast cancer -- and millions abruptly stopped taking their daily pills. A large study showed that women taking hormone replacement therapy had a 26 percent increase in the risk of breast cancer. A less frightening way to state the same thing is to note that 38 out of 10,000 women taking hormones got breast cancer a year, compared to 30 per 10,000 not taking hormones, said Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital. That's a difference of only eight women per 10,000 per year -- certainly significant, but maybe not enough to justify ending a prescription.
9. Listen closely even to non-numerical claims, said Dr. Richard Kravitz, a professor of medicine at the University of California at Davis. An ad might say, "There is no treatment more effective than drug X," he said. "But that may be true because nobody has looked." Another common ad statement is, "Drug X has been proven effective for condition Y," when the real truth may be that 70 percent of people with the condition got better by themselves and 75 percent with the drug. "So the drug is effective, but not that effective," he said.
10. The most important tip of all? If a drug or procedure sounds too good to be true, it probably is.
Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.
