Case control study vs prospective cohort study
Case-controls can provide fast results and they are cheaper to perform than most other studies.
Case control study vs prospective cohort study
Abstract This article discusses the observational analytic study designs, i. This study design can be used to test for several risk factors for a single disease and is especially useful for rare diseases. About the Author: With expertise in epidemiology, biostatistics and quantitative research projects, Annette Gerritsen, Ph. The descriptive epidemiology convincingly indicated that the outbreak originated at the luncheon, but which specific dish was responsible? For this reason, retrospective investigations are often criticised. The case—control study goes backward from the disease status so is more useful for rare diseases and for evaluating multiple risk factors, but it cannot determine causality, and there are chances of recall bias affecting the results of the study. This study design is generally a good choice when dealing with an outbreak in a relatively small, well-defined source population, particularly if the disease being studied was fairly frequent. As such, controls should also be selected carefully. Most sources of error due to confounding and bias are more common in retrospective studies than in prospective studies.
Case-Control studies Case-Control studies are usually but not exclusively retrospective, the opposite is true for cohort studies. Prospective studies usually have fewer potential sources of bias and confounding than retrospective studies.
Does it use appropriate inclusion and exclusion criteria?
Case control study vs cohort study
See Figure 1 for a pictorial representation of a case-control study design. If the outcome of interest is uncommon, however, the size of prospective investigation required to estimate relative risk is often too large to be feasible. Impact of windows and daylight exposure on overall health and sleep quality of office workers: a case-control pilot study. The confidence interval also provides a measure of the precision of the estimated risk ratio. For example, the table below summarizes the findings from the survey regarding the incidence of disease in those who ate the cheese appetizer compared to those who did not eat it. Retrospective cohort studies are NOT the same as case-control studies. If the cases have a substantially higher odds of exposure to a particular factor compared to the control subjects, it suggests an association. Prospective studies usually have fewer potential sources of bias and confounding than retrospective studies. They look back to assess whether there is a statistically significant difference in the rates of exposure to a defined risk factor between the groups. You should take special care to avoid sources of bias and confounding in retrospective studies. The greater the difference in the exposure between the two groups, the higher the value of the OR. For this reason, retrospective investigations are often criticised. At the same time, there will always be subjects who are exposed to the risk factor but not diseased cell 'b' as well as those that are not exposed to the risk factor but are diseased cell 'c'. Table 2.
Prospective A prospective study watches for outcomes, such as the development of a disease, during the study period and relates this to other factors such as suspected risk or protection factor s.
Many valuable case-control studies, such as Lane and Claypon's investigation of risk factors for breast cancer, were retrospective investigations. The direction of the study is from the exposure status to the outcome status [Table 4] and is useful for comparing the incidence of disease in the two groups.
Does the study use matching or pairing appropriately to avoid the effects of a confounding variable? Case Reports Definition A study that compares patients who have a disease or outcome of interest cases with patients who do not have the disease or outcome controlsand looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease.
A case-control study begins with the selection of cases people with a disease and controls people without the disease. However, these two still constitute the most common study designs that are used in the epidemiological field along with the cross-sectional studies and the clinical trials.
Increasing the number of controls above the number of cases, up to a ratio of about 4 to 1, may be a cost-effective way to improve the study. Health officials noted that an unusually large number of cases had been reported during a span of several days.
Descriptive epidemiology was conducted, and hypothesis-generating interviews indicated that all of the disease people had attended a parent-teacher luncheon at a local school.
based on 22 review