Disclaimer Outbreak of acute renal failure in Panama in It is commonly used in industry and can be found in commercial products such as resins, antifreeze, inks and glues. In addition, DEG has also been found as a contaminant of raw materials used in the production of pharmaceuticals. Most recently, paediatric medicinal syrups contaminated with DEG have led to the deaths of 33 of 36 children known to be affected in India in 10 and of 85 of children known to be affected in Haiti in —
Introduction to study designs - case-control studies Introduction Learning objectives: You will learn about basic introduction to case-control studies, its analysis and interpretation of outcomes.
Case-control studies are one of the frequently used study designs due to the relative ease of its application in comparison with other study designs. This section introduces you to basic concepts, application and strengths of case-control study. This section also covers: Issues in the design of case-control studies 2.
Common sources of bias in a case-control study 3. Analysis of case-control studies 4. Strengths and weaknesses of case-control studies 5. Nested case-control studies Read the resource text below. Resource text Case-control studies start with the identification of a group of cases individuals with a particular health outcome in a given population and a group of controls individuals without the health outcome to be included in the study.
In a case-control study the prevalence of exposure to a potential risk factor s is compared between cases and controls. If the prevalence of exposure is more common among cases than controls, it may be a risk factor for the outcome under investigation.
A major characteristic of case-control studies is that data on potential risk factors are collected retrospectively and as a result may give rise to bias. This is a particular problem associated with case-control studies and therefore needs to be carefully considered during the design and conduct of the study.
Issues in the design of case-control studies Formulation of a clearly defined hypothesis As with all epidemiological investigations the beginning of a case-control study should begin with the formulation of a clearly defined hypothesis.
Case definition It is essential that the case definition is clearly defined at the outset of the investigation to ensure that all cases included in the study are based on the same diagnostic criteria.
Source of cases The source of cases needs to be clearly defined. Selection of cases Case-control studies may use incident or prevalent cases. Incident cases comprise cases newly diagnosed during a defined time period.
The use of incident cases is considered as preferential, as the recall of past exposure s may be more accurate among newly diagnosed cases. In addition, the temporal sequence of exposure and disease is easier to assess among incident cases.
Prevalent cases comprise individuals who have had the outcome under investigation for some time. The use of prevalent cases may give rise to recall bias as prevalent cases may be less likely to accurately report past exposures s. As a result, the interpretation of results based on prevalent cases may prove more problematic, as it may be more difficult to ensure that reported events relate to a time before the development of disease rather than to the consequence of the disease process itself.
For example, individuals may modify their exposure following the onset of disease. In addition, unless the effect of exposure on duration of illness is known, it will not be possible to determine the extent to which a particular characteristic is related to the prognosis of the disease once it develops rather than to its cause.
Source of cases Cases may be recruited from a number of sources; for example they may be recruited from a hospital, clinic, GP registers or may be population bases. Population based case control studies are generally more expensive and difficult to conduct. Selection of controls A particular problem inherent in case-control studies is the selection of a comparable control group.
Controls are used to estimate the prevalence of exposure in the population which gave rise to the cases. Therefore, the ideal control group would comprise a random sample from the general population that gave rise to the cases.
However, this is not always possible in practice. The goal is to select individuals in whom the distribution of exposure status would be the same as that of the cases in the absence of an exposure disease association.
That is, if there is no true association between exposure and disease, the cases and controls should have the same distribution of exposure. The source of controls is dependent on the source of cases. In order to minimize bias, controls should be selected to be a representative sample of the population which produced the cases.the role of microfinance in the socio-economic development of women in a community: a case study of mpigi town council in uganda.
by martha nakakuta luyirika. Definition of case - an instance of a particular situation; an example of something occurring, an instance of a disease, injury, or problem, a legal ac.
Case control studies are observational because no intervention is attempted and no attempt is made to alter the course of the disease. The goal is to retrospectively determine the exposure to the risk factor of interest from each of the two groups of .
Case-control studies are one of the frequently used study designs due to the relative ease of its application in comparison with other study designs.
This section introduces you to basic concepts, application and strengths of case-control study. Nationally Consistent Collection of Data on School Students with Disability Hypothetical case study – Catherine Catherine is a year 4 student at a small remote primary school.
The following is a case study of one entrepreneur's transition from a traditional development cycle to continuous feelthefish.com people still find this idea challenging, even for companies that operate solely on the web.