As you learn more about menopause, you will come across many competing claims and statistics. Understanding the different types of research studies behind these numbers can help you evaluate their results and make informed health care decisions. There are three major types of research studies:
1. In a cohort study, researchers follow a group, or cohort, of women for a specific period. The researchers determine whether the women experience a particular exposure, such as whether they take a drug or supplement, exercise, smoke, or eat certain foods. The researchers follow all the women in the cohort to see whether they experience a particular outcome (for example, development of a certain disease). Cohort studies can detect relationships between exposure and outcome, but they cannot definitively claim that the exposure or treatment causes the outcome.
2. In a case-control study, researchers investigate two groups of women, one who have a certain outcome, such as a disease, and another who do not. The group of women with the disease is called the case group, while the other is known as the control or comparison group. Researchers determine whether the women experienced specific exposures of interest (such as diet or exercise).
3. In a randomized controlled trial, researchers recruit women to participate in a study. Once the women agree to participate, they are assigned randomly to receive either the treatment being tested, or a placebo (such as a sugar pill). The study is called randomized because there is no classification to determine whether a woman gets the treatment or the placebo. If neither the women participating in the study, nor the health professionals working with them, know which group each woman is in, the study is called a double-blind. The placebo helps with the blinding as the woman and her doctor cannot tell by looking at the pill whether it is an active treatment or a sugar pill. Randomized, double-blind placebo controlled trials are considered the "gold standard" in research. They attempt to test whether treatment X causes outcome Y, and they can come the closest to claiming causation because of the blinding, the randomization, and the use of a placebo. The idea is that everything is constant, except whether women are taking the placebo or the actual treatment.