Case control studies

Introduction A case-control study is designed to help determine if an exposure is associated with an outcome i.

Case control studies

A cohort study design works well in these circumstances. However, in most outbreaks the population is not well defined, and cohort studies are not feasible. A good example of this is an actual outbreak of hepatitis A that occurred in Marshfield, MA in In addition, a case of hepatitis A in a Plymouth resident, employed in Marshfield, was reported.

Within Case control studies short period of time 20 cases of hepatitis A were identified in the Marshfield area. The epidemic curve suggested a point source epidemic, and the spot map showed the cases to be spread across the entire South Shore of Massachusetts, although the pattern suggested a focus near Marshfield.

Hypothesis-generating interviews resulted in five food establishments that were candidate sources. Moreover, the disease was rare, so that even if they interviewed a sample of patrons at each of the restaurants, it is most likely that few, if any would have had recent hepatitis, even from the responsible restaurant.

In a situation like this a case-control design is a much more efficient option. The investigators identified as many cases as possible 19 agreed to answer the questionnaireand they selected a sample of 38 non-diseased people as a comparison group the controls.

Case control studies

In this case, the "controls" were non-diseased people who were matched to the cases with respect to age, gender, and neighborhood of residence. Investigators then ascertained the prior exposures of subjects in each group, focusing on food establishments and other possibly relevant exposures they had had during the past two months.

When using a case-control strategy for sampling, it is not possible to calculate the incidence attack rate in exposed and non-exposed subjects, because the denominators of the exposure groups are unknown.

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However, one can calculate the odds of disease in exposed and non-exposed subjects, and these can be expressed as an odds ratio, which is a good approximation of a risk ratio in a situation like this, i. An odds ratio can be computed for each of the possible sources.

Consider the following example:Case-control study designs are used to estimate the relative risk for a disease from a specific risk factor. The estimate is the odds ratio, which is a good estimate of the relative risk especially when the disease is rare.

Case-control studies are useful when epidemiologists to investigate an. NEWCASTLE - OTTAWA QUALITY ASSESSMENT SCALE CASE CONTROL STUDIES Note: A study can be awarded a maximum of one star for each numbered item within the Selection and. The first prominent analysis which drew attention to a potential correlation between ARB therapy and neoplastic diseases was published by Coleman in They processed the data of , patients from 27 studies (subjects with hypertension, cardiac failure, coronary heart disease, or renal disease).

C-reactive protein (CRP) a protein that is produced in the liver in response to is a biomarker of inflammation that is strongly associated with the risk of cardiovascular events, such as myocardial infarction and stroke. Calcification the process of deposition of calcium salts.

Case control studies

In the formation of bone this is a normal condition. This page indexes abstracts, full text articles, and other material about the relationship of circumcision status and the risk of contracting urinary tract infection (UTI). A case–control study (also known as case–referent study) is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute.

Example of a Case-Control Study