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Designing the Low-Fat / Breast Cancer Clinical Trial
This clinical trial, known as The Women's Health Initiative Randomized Controlled Dietary Modification Trial, lasted twelve years and included 48,835 participants. Why so many and why so long?
Realize that this study was designed in the early 1990s which means, of course, that the investigators were using what was understood about dietary fat and breast cancer at that time. It was considered such an important question that the investigators were willing to devote more than a decade of their careers and the National Institutes of Health was willing to fund such a colossal project.
All of the women were observed for as long as they were in the study. Some were simply given the standard advice to watch their diet and were given some pamphlets on diet to take home. Others underwent what is known as an "intervention,' which had been proven effective in lowering dietary fat already. In this case, it was a series of intense training in low fat diets and regular meetings in groups to reinforce their low fat eating habits. The group that was only observed is called the "control" group; the one receiving the training and meetings is the "experimental" group.
Statistical calculations were made to determine how many and how long. It was decided that ten years would be long enough to follow these women, who ranged in age from 50 to 79 years. Previous research had suggested that ten years would be long enough for the dietary differences to have an effect. The study lasted twelve years because it took two years to recruit enough participants. The ten-year period, combined with the large number of participants, would also be long enough for some of the women in the control group to develop breast cancer - a morbid concept, but one that is tolerated in studies designed this way. Any decrease in breast cancer in the experimental group would be measurable by comparing the two groups.
Next time: Interpreting the Results
-Joe
Related Topics: The Sonoma Diet: Promoting a Lifestyle, 5 Super Nutrients for Living Longer
Technorati Tags: breast cancer, low fat diet
Realize that this study was designed in the early 1990s which means, of course, that the investigators were using what was understood about dietary fat and breast cancer at that time. It was considered such an important question that the investigators were willing to devote more than a decade of their careers and the National Institutes of Health was willing to fund such a colossal project.
All of the women were observed for as long as they were in the study. Some were simply given the standard advice to watch their diet and were given some pamphlets on diet to take home. Others underwent what is known as an "intervention,' which had been proven effective in lowering dietary fat already. In this case, it was a series of intense training in low fat diets and regular meetings in groups to reinforce their low fat eating habits. The group that was only observed is called the "control" group; the one receiving the training and meetings is the "experimental" group.
Statistical calculations were made to determine how many and how long. It was decided that ten years would be long enough to follow these women, who ranged in age from 50 to 79 years. Previous research had suggested that ten years would be long enough for the dietary differences to have an effect. The study lasted twelve years because it took two years to recruit enough participants. The ten-year period, combined with the large number of participants, would also be long enough for some of the women in the control group to develop breast cancer - a morbid concept, but one that is tolerated in studies designed this way. Any decrease in breast cancer in the experimental group would be measurable by comparing the two groups.
Next time: Interpreting the Results
-Joe
Related Topics: The Sonoma Diet: Promoting a Lifestyle, 5 Super Nutrients for Living Longer
Technorati Tags: breast cancer, low fat diet
