![]() ![]() For example, a study of environmental exposures during pregnancy and fetus malformation may reveal a higher proportion of exposures among women who had an affected fetus because they were more aware and recalled all potential hazards that may have caused the severe adverse outcome of their pregnancies. ![]() However, a case–control study is prone to various sources of bias, notably “recall bias”, where people with (or without) a studied outcome may tend to better remember their exposure status. This presents an important advantage as it reduces the cost and time necessary for the study of such conditions. Case–control studies may be vital to define the differences between the sick and the control groups in an epidemic or outbreak situation.Ĭase–control studies are ideal for the study of rare disease or conditions that are slow to evolve, as they permit the assembly of a group of cases of appropriate size for analysis, without requiring an extremely large study population. It is a ratio of the odds of exposure among cases to the odds of exposure among controls. The odds ratio is commonly used to summarize findings of case–control studies. Case–control studies are defined as retrospective (defining the outcome status and then looking at the exposure). This study was confirmed by studies in other European countries which had licensed thalidomide, which led to the FDA stopping approval for this drug in the USA, and later to its being banned in countries where it was already in use. An example is the study of the occurrence of a serious upper limb defect (phocomelia) in children born in Germany in the late 1950s, which showed that of those born with this defect, 41 out of 46 mothers had taken the medication thalidomide as an antinausea pill promoted for use during pregnancy, whereas none of the 300 control mothers with normal children had done so. They compare two similar population groups for their exposure outcomes, one with the disease or condition and the other without. These studies are retrospective, taking a known outcome status (e.g., disease status) and looking at the exposure status. ![]() Varavikova MD, MPH, PhD, in The New Public Health (Third Edition), 2014 Case–Control StudiesĬase–control studies are observational studies of people with the disease (or other outcome variable of interest) and a suitable control group of people without the disease. Four years later, a significant inverse association between fiber intake and prostate cancer risk was observed in another US-based case–control study. 46 In the first US-based case–control study on the association between dietary fiber and risk of prostate cancer, 47 dietary fiber intake was not associated with risk of prostate cancer, whereas a significant inverse association between dietary lignans and prostate cancer risk was observed. 45 In this study, 46 no association between total fiber intake and risk of prostate cancer was observed, but vegetable fiber was significantly inversely associated with risk of prostate cancer, whereas grain fiber was positively associated with prostate cancer risk. 45 In 2004 a case–control study on the association between dietary fiber and risk of prostate cancer was published, 46 which had a more than four-fold number of cases compared to the case–control study from 1995. The first case–control study relating dietary fiber to risk of prostate cancer, which was published in 1995, found no association. In two early case–control studies conducted in the 1990s, no significant association between whole meal bread 43 or whole grain foods (essentially bread and pasta) 44 and risk of prostate cancer was observed. Katharina Nimptsch, in Wheat and Rice in Disease Prevention and Health, 2014 Case–Control Studies ![]()
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