Medical research studies are an important way of advancing our medical knowledge. Medical research studies are done to ensure that any new treatment is both effective and safe, and there are a number of reasons why they are critical to our understanding.
Medical Research Studies Are About Probability
It may seem strange to hear, but no study can prove with complete certainty that one thing causes another. Instead, clinical trials help us understand what things are most likely linked. As an example, most people probably believe that smoking causes cancer, and that this is a proven fact. Actually, no medical study has or could ever prove this to be a fact. But medical studies can show that the links between two things–such as smoking and lung cancer–are so tight and so consistent that there is a very high probability that the first is influencing the second.
You may have seen or heard reference to something called a “p-value” in a report about a clinical study. The p-value is how researchers estimate the likelihood of something being due to chance. If a p-value is less than 0.05, for example, that means the likelihood that the outcome is due to simple chance is less than 5%.
Medical Research Studies Usually Evaluate Relative Risk, Not Absolute Risk
As a simple example, many people believe that eating red meat is dangerous because they see headlines saying that a study showed meat eaters’ risk of developing cancer was, say, 45% higher than that of non-meat eaters. These headlines are actually describing relative risk, not absolute risk; and relative risk is meaningless if you don’t know the absolute risk. Say that one out of every 10,000 people who flies dies in a plane crash. If you fly once per year, we could say your absolute risk of dying in a plane crash is 0.01%. Now say that you fly twice a year. Your absolute risk is still only 0.02%. That’s so small that few people would worry about taking that second flight. Yet since .02 is twice as large as .01, we could write a headline saying that those who fly twice a year increase their risk by 100%. This would be scary unless you knew the absolute risk numbers.
Medical Research Studies Deal With Confounding Factors
One of the very reasons for a Phase 1 clinical trial, followed by a Phase 2 and so on is to try to minimize the confounding factors. As a clinical drug development or other medical study progresses, it will attempt to weed out as many confounding factors as possible by putting similar people into groups of similar sizes and adjusting data to compensate for the inevitable differences that confound the results. A confounding factor is any issue that might make it more difficult to work out exactly which is causing what.
In the meat example above, the death rates of those who eat the most meat are usually being compared with those who eat none at all–such as vegetarians. The problem is working out confounding factors. People who eat a lot of meat are usually not nearly so concerned with their health as vegetarians. This means they are also much more likely than vegetarians to smoke, drink heavily, ignore their doctor’s advice, and fail to exercise. They are also more likely to eat processed foods and larger amounts of sugar and refined grains. They also tend to be older and are more likely to have diabetes. It is very difficult, then, to work out whether–out of all those differences between these two groups–the one primary factor driving the increased rate of death for the first group is actually meat.
It is precisely because of these issues with probability, confounding factors, and the need to differentiate between absolute and relative risk that medical research studies are so vitally important. Without them, it would impossible really advance medicine, since every advancement would be a blind shot in the dark. With clinical trials, we can make much more informed and educated guesses that can lead to real breakthroughs.