Retrospective studies

Case-control (retrospective) studies are one of the basic types of observational studies in the medical market – similar to cohort studies, they serve to quantify the relationship between exposure (the causative agent) and its effect (disease phenomenon).

The idea of the research process is based upon a comparative analysis of a group of people suffering from a particular disease (research group) and a group of healthy people (control group) – within the scope of the analysis, you begin from the endpoint (moment of exposure), and the risk of exposure is assessed retroactively.

Use of case-control studies

Observational studies of this type are carried out in order to:

• Define the risk factors (including those specific for rare diseases)
• Diagnose the causes of diseases (including chronic diseases – cancer, heart disease, metabolic disorders)

Retrospective epidemiological studies are particularly applicable to those ailments which would require very large cohorts or long exposure times to research. They also support the analysis of the epidemiological situation of dynamic populations which demonstrate considerable mobility of participants, and help streamline the evaluation of public health programs.

Methodology of case-control studies

When designing a case-control study, one has to bear in mind the fact that factors which may interfere with the results of the analysis are primarily:

Personal bias when selecting specific people for research and control groups – different ways of participant selection, use of different sources of population

Measurement errors – differences in the accuracy of the exposure indication, and the condition of the control group

Impact of distortion factors on the size of sample group size

Cohort studies

Cohort studies are a type of prospective observational study, the implementation of which is justified especially if it is impossible to perform clinical measurements for ethical reasons

Application of cohort studies:

Cohort studies are conducted long term to verify the occurrence of certain medical phenomena such as:

• Diseases, and medical events related to them;
• Positive and undesirable effects of drugs and other medicinal products;
• Health status of inhabitants of a given area.

Observational cohort studies also provide the potential for causal analysis of exposure to a variety of risk factors (e.g. smoking, drug use, diet, etc.). The results of the study allow to determine the relative risk, for example, by comparing the risk of developing a cardiovascular disease in people on a high fat or vegetarian diet.

Depending on the purpose of the research, we forecast the risk based on the following data:

• Incidence
• Mortality rate
• Simultaneous incidence of other diseases;
• Results of cyclic laboratory measurements (blood, urine, feces, x-ray, USG, etc.);
• Various types of socio-demographic variables (age, sex, place of residence etc.);
• Predispositions to the disease.

Methodology of cohort studies

Cohort studies are non-interventional in nature, which means that any action likely to trigger a specific effect on the members of the observed cohort should be avoided. It should only be limited to cyclical observation and collection of data obtained within it.

Before starting the study, we define in detail:

• Characteristics of cohort members – according to pre-determined research goals;
• Length of observation;
• Exposure factors;
• Procedures for verifying the results of the final events;
• Assumed representativeness.

We also verify whether a medical event (e.g. incidence) has not occurred during recruitment or before it. Such cases are excluded from the study.

Types of cohort studies

Our company realizes cohort studies of controlled and uncontrolled nature. For controlled measurements, each person in the cohort is exposed to the same risk factor or medical product. On the other hand, uncontrolled observational studies assume the division of the cohort into at least two groups that are affected by different factors. We conduct research on both closed and open (dynamic) cohorts.

Expected benefits

Cohort studies enable proper health policy planning, based on the obtained results. They also allow for reliable verification of the effectiveness of medicinal products, and their adverse effects. This type of observational study, unlike clinical trials, does not raise any ethical concerns.

Why we are the best choice when you need to commission a cohort study.

Our company has been active in the medical research market for over 12 years, so we are able to guarantee the implementation of highest possible quality cohort studies that support all of the latest methodological standards. We encourage you to contact us for details of possible cooperation.