The Amazing Maze of Medical Studies
By Linda Hepler, BSN, RN
I’d finally worked up the courage to schedule my first colonoscopy when I was greeted by the headline: “Cleansing the Bowel for Colonoscopy May Harm the Kidney” on the health news Website, Medpagetoday.com. Reading on, I learned that doctors at Columbia College of Physicians and Surgeons in New York had discovered a pattern of kidney failure among patients who had taken the bowel cleansing drink most often prescribed before undergoing a colonoscopy. While the authors of the study were careful to point out that only those with certain risk factors (being over 50, having hypertension, using drugs that were ACE inhibitors, and not re-hydrating adequately after the bowel prep) had developed kidney failure, the news was nevertheless scary enough to me that I reconsidered the colonoscopy.
As a nurse, I’m well aware that colorectal cancer claims more than 50,000 lives each year. And while there are other forms of colorectal cancer screening (serial stools for occult blood and Sigmoidoscopy), colonoscopy is the best tool for detecting early—and easily curable—stages of this disease. But after reading this study, I became apprehensive about the bowel preparation. I envisioned a future in which I was cancer free but hooked up to a kidney machine.
If, like me, you often feel confused by research-study findings, it’s understandable. After all, “research” is science, and science is supposed to be exact – right? Actually, science is a quest for truth, and like any search it can take unexpected twists and turns. According to a report published recently in the Journal of the American Medical Association, a review of major studies published in three prominent medical journals between 1990 and 2003 found that as many as a third of these study results were contradicted — or at least weakened — by subsequent studies. One well-known example of this is hormone therapy for menopause. Not long ago, research suggested that hormone treatment for menopausal women was not only a panacea for pesky symptoms like hot flashes, it could also function as protection against heart disease — until further research concluded that for most women, hormone therapy actually increases rather than diminishes the risk of heart disease.
This is not to say that one should throw in the towel when it comes to reading about the latest medical research. But we should be a tad more skeptical while synthesizing the findings, and more aware of the limitations of science. A good way to develop a critical eye is to learn more about how research is performed, how it’s reported, and what the findings may mean to you.
Different Types of Research, Different Conclusions
One of the first things to understand is that there are many different types of medical research, each with its own strengths and weaknesses. One major distinction is between observational and intervention studies. An observational study is when scientists observe groups of people without changing any of the variables in their lives, such as medication, diet, or lifestyle. Observational research may be used to find possible reasons why a disease has occurred in some people and not in others. An observational study might, for example, compare a group of people with diabetes to another group without diabetes, and then would look for differences and similarities between the two groups. An observational study might also follow groups of healthy people for a long time, looking for factors that contribute to the development of a certain disease.
Observational studies often suggest areas for further research rather than solid conclusions, because there is no control over study participants or the many factors that may contribute to certain findings. An observational study might suggest that people who eat more fruits and vegetables and fewer fats are thinner than those who eat fewer fruits and vegetables and more fats. But this doesn’t take into consideration that the healthier eaters may exercise more, or be genetically predisposed to being thin. Further research would be needed to find a definitive answer.
Intervention studies are controlled in the hope that a more conclusive answer to a scientific question can be found. In this type of study, researchers randomly divide a group of people, control various factors, and compare the results. One common intervention study is the randomized clinical trial that’s often used to determine the effectiveness of a medication or treatment. Here, one group (the “control group”) receives a pill that looks exactly like the medication being tested, but actually isn’t. This false medication is called a placebo. The other group, called the “treatment group,” receives the real medication. By comparing the responses of the two groups to the real medication versus the placebo, researchers are able to determine whether or not the medication or treatment is effective. They can also gain valuable information about side effects that may occur in those taking the real medication.
Even if the research topic is the same, different studies can yield different conclusions because of disparate study methods. This is to be expected; arriving at a final answer often requires looking at things in various ways.
Looking at the Source
It’s not always easy to find all the information you need by reading the health section of your newspaper. Sometimes overly eager media will herald preliminary findings, both positive and negative, from information presented by researchers at a medical conference – prior to the conclusion of the study. Such exaggerated and misleading headlines don’t tell the whole story.
So when a medical headline captures your interest, it’s best to learn more by finding the original story online or in a library. The writing may be more technical than you’re used to, but that shouldn’t stop you from absorbing information that will help you decide whether or not to consider the treatment. When reading medical research, ask yourself the following questions:
How was the study conducted?
Was the research done on animals or on people? Findings from studies performed on people may be more relevant to you. Furthermore, if the study participants were human, did you share such characteristics with them as gender, age, ethnic background, and medical history? If the people studied were entirely different than you, the research findings may be far less relevant to your life.
Who conducted the study?
Scientists at a reputable institution – a large teaching hospital or medical school – may be more qualified to conduct a medical study on a complex issue than medical researchers not affiliated with a well-known organization.
Who funded the study?
Medical research findings are not necessarily skewed by how they’re funded. But vested interests may influence how the findings are reported. A medication study sponsored and promoted by the pharmaceutical company that produces the drug being researched might highlight the positive findings and downplay the negative.
Where were the study results published?
Credible medical journals like JAMA, Lancet, and the New England Journal of Medicine screen articles for conflicts of interest prior to publishing them. Respected journals also seek to report well-designed and properly conducted studies.
Searching for answers
If after reading the original study you still want to learn more, continue your search via the Internet or the library:
Do other studies support the findings?
A single study seldom provides a definitive answer. Is there other research out there that points in the same direction? Fitting new studies into what has already been published helps bring the big picture into focus.
Are there any long-term data on the particular topic?
Many promising medical studies are just that – a promise. The findings are often too preliminary to draw a conclusion about changing anything in your own life. It may take many years, especially with new drugs and treatments, to determine how safe and effective they are over the long run.
What do reputable organizations say about the study?
Early research on arthritis drugs like Celebrex, Bextra, and Vioxx suggested that these medications might increase the risk of serious heart disease. When the American Heart Association issued an advisory regarding the use of these drugs based on the research findings, it became evident that there was a serious concern.
Get another opinion
Before changing something in your life such as a medication, treatment, or dietary practice, it helps to talk with someone who can give you an honest and educated opinion – your doctor. He or she has knowledge about your individual health and perhaps can explain why a particular drug or treatment may or may not be a good choice for you.
Make an appointment for a consultation and take your notes and a list of questions with you, but keep in mind your doctor may not have read the particular medical research topic that interests you. If you bring a list of sources, the doctor can read the study and get back to you at a later date.
If you’ve gained sufficient information about a medical-research study to know that it’s not worth altering anything in your own life just yet, you’re still ahead of the game. You’ll be prepared with what you already know when the next headline on the same topic hits the press. And that may be sooner than you think.
