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EPIDERMIOLOGY FUNDAMENTALS. - Coggle Diagram

- - - - To know the distribution and characteristics of the problems that affect people and to know when there is an endemic or epidemic phenomenon, epidemiology helps with its methods and techniques to know how diseases affect the individual.
        The evidence collected on groups of individuals is used to identify the signs and symptoms of a particular disease or problem and thus characterize a clinical picture, to know the natural history of a process and to look for the best points to intercept this process for the benefit of the patient.
        patient.
        
        Characteristics of the descriptive studies
        
        There are different ways of organizing such studies, the simplest of which is to simply describe a problem by recording the characteristics of the people affected and the environment.
        description of a problem by recording the characteristics of the people affected and the environment.
        Key concepts:
        
        The descriptive approach is the cornerstone in epidemiology.
        
        Descriptive epidemiology makes it possible to establish patterns of clinical pictures and to establish the natural history of diseases and health problems.
        
        Although descriptive studies do not formulate explicit study hypotheses, in practice they are not exempt from the formulation of study hypotheses.
        
        Descriptive epidemiology is the great supplier of working hypotheses for analytical epidemiology.
    - - It is an observational design, passive in terms of the participation of the researcher, who orders the information after the events that gave rise to it have already occurred.
        the researcher, who orders the information after the events that gave rise to it have already occurred.
        It requires that the steps of an epidemiological investigation have been previously fulfilled. That is, working hypotheses should have emerged in the light of the findings of the epidemiological description.
        
        Temporal relationships between the variables studied .
        The evaluation of exposure between cases and controls is retrospective 2 . This means inquiring among the subjects about the history of exposure prior to the occurrence of the outcome. The establishment of a chronological order between the presence of eventual causal factors and outcome would seem to be intuitively simple using this methodological approach, but this is not the case.
    - - Main uses of cohort studies
        
        To test causality and risk hypotheses: among observational designs, cohort studies provide the most rigorous information in favor of causality and risk. As already mentioned, absolute certainty of the causal process can only be provided by experimental design. They have the additional advantage of following the same logic of clinical thinking (exposure precedes outcome).
        
        Measuring the incidence of a disease or condition.
        One of the products of greatest interest in a cohort study is obtaining incidence rates of the disease or condition under study.
        
        They allow the quantification of the risk:
        The ratio between the incidence rate of exposed subjects in relation to that of non-exposed subjects gives rise to the so-called relative risk.
        the relationship between the incidence rate of exposed subjects in relation to that of non-exposed subjects gives rise to the so-called relative risk, which makes it possible to establish the magnitude of the risk associated with the exposure analyzed.
        To study the natural history of the disease: Cohort studies allow to carry out the following studies Cohort studies make it possible to follow up healthy individuals with standardized diagnostic criteria and methods. In this way, it is possible to identify at an early stage the characteristic elements of a disease, as well as factors associated with its earliest stages.
        early stages.
  - - - Experimental studies may be considered:
        Therapeutic (or secondary prevention) are performed on patients with a given disease and determine the ability of an agent or procedure to reduce symptoms, to prevent recurrence or to reduce the risk of death from that disease.
        Preventive (or primary prevention) studies evaluate whether an agent or procedure reduces the risk of developing a disease. Thus, experimental preventive studies are conducted among healthy individuals who are at risk of developing a disease. This intervention can be on an individual or community basis to a whole population.
        
        Experimental designs in epidemiology are of 3 types depending on on whom the study is performed: I. Randomized Controlled Clinical Trial, II Field Trial, III Quasi-experimental or Community or Intervention Trial.
        
        Randomized Controlled Clinical Trial
        It is a prospective study that attempts to compare the effect and value of one or more interventions in humans with a medical condition. Therefore the intervention is performed on a group of individuals suffering from a disease and through a randomized process it is decided who will constitute the control group, receiving another or no intervention.
        control group, receiving another intervention or no intervention.
        
        Field Trial.
        They deal with subjects who have not yet acquired the disease or with those who are at risk of acquiring it and study disease preventive factors such as the administration of vaccines or the follow-up of diets.
        
        Community or intervention quasi-experiments or trials .
        These studies are usually known as community or intervention trials. They are part of experimental studies because they are used to test a hypothesis and are designed considering an experimental and a control group. The difference lies in the fact that the intervention and control groups are not individuals chosen at random but entire communities (there is manipulation, not randomization).