Before new drugs are approved for use, they go through a multi-step approval procedure. In recent years, the process has become more globalized, but a new study suggests that the results of clinical trials in one country or region may not be relevant for patients in another.
For many new drugs, the biggest market may be in Europe and North America, but when the testing moves out of the lab and into human subjects, increasingly the venues include low- and middle-income countries.
As a researcher and cardiologist, Dr. Christopher M. O'Connor, of the Duke University Medical Center in North Carolina, has seen studies of new-drug effectiveness that seemed to have different results in different countries. So he combined the results from several studies investigating the effectiveness of drugs called beta blockers for patients with heart failure.
The studies enrolled patients in both the United States and other countries. Overall, O'Connor says, beta blockers reduced the risk of death by about 32 to 35 percent.
"But what we found is that, in the United States, it was only an eight percent reduction; in the rest of the world it was a 36 percent reduction," he says.
So the question is, why?
"We know that there's differences in the way racial and ethnic groups handle drugs, for example. The way they metabolize drugs. There are genetic differences. There are important cultural and social differences."
Cultural and social differences, he says, may be reflected in a willingness to participate in a clinical trial or follow instructions if you do.
Combining the results of studies done in several countries can mask geographic differences. A drug that seems generally beneficial across the board can be very effective in one country, but nearly useless in another. And O'Connor says that could hurt patients.
"Once these trials suggest a benefit and get approved, they're going to be used by everybody across the globe," O'Connor says. "And what you don't want to have is a situation that you approve a drug or a device based on a global trial, and then realize five years later that, well, it didn't work in this part of the world or that part of the world."
O'Connor's study of how beta blockers vary in effectiveness in different geographic regions is published online by the Journal of the American College of Cardiology.