Large scale studies have been undertaken to find the risk factors for many common diseases, including CVD. Epidemiologists (scientists who study patterns in the occurrence of disease) look for correlations between a disease and specific risk factors.
Two commonly used designs for this type of study are;
•Cohort studies- a group of people are followed over time to see who develops a disease •Case control studies- a group of people who have the disease are compared with a group who don’t.
Cohort studies follow a group of people over time to see who develops the disease and who does not. During the study people’s exposure to suspected risk factors is recorded so any correlations between the risk factors and disease development can be identified. It may take a long time for the condition to develop so these studies can take years and be very expensive.
•Case control studies.
In a case control study a group of people with a disease (the cases) are compared with a control group of individuals who do not have the disease. Info is collected about the risk factors that they have been exposed to, allowing factors that may have contributed to development of the disease to be identified. The control group should be representative of the population from which the case group was drawn. Sometimes controls are individually matched to cases: known disease-risk factors such as age and sex are then similar in each case. This allows scientists to investigate the potential role of unknown risk factors. It should be noted that factors used to match the cases cannot be investigated within the study, so it is important not to match on variables which could potentially be risk factors.
Features of a good study.
To identify correlations between risk factors and disease, studies need to be carefully designed. Recording a higher rate of heart disease in 50 people who drink more than the recommended...