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Fundamentals of Epidemiology - Coggle Diagram

- - - - Epidemiology is based on the scientific method for obtaining knowledge. Faced with a health problem, and given the available data on it, we formulate a hypothesis, which is translated into a series of consequences that can be tested by experimentation. A research project is then carried out, starting with the collection of data and its subsequent statistical analysis, with which measures of association, impact and contrast of hypotheses are calculated.
        
        Epidemiology is considered the basic science for preventive medicine and a source of information for the formulation of public health policies. Epidemiology primarily studies the cause-effect relationship between exposure and disease. Diseases do not occur randomly; they have causes, many of them of human origin, which can be avoided. Therefore, many diseases could be prevented if their causes were known. Epidemiological methods have been crucial in identifying numerous etiological factors which, in turn, have justified the formulation of health policies aimed at the prevention of disease, injury and premature death.
        
        In developing countries, such as Panama, there is a growing need for clinical epidemiology studies. There are very limited resources available for health services that can be applied more effectively only if the frequency and distribution of disease in the population is known. Epidemiology is also used to investigate the etiology and natural history of diseases. Clinical and preventive care must be based on the strongest research evidence, and should be judged by the results obtained, at a cost that society can afford.
        
        Epidemiology has contributed to enrich the scientific knowledge of disease processes. In Occupational Health, labor or occupational epidemiology is part of the techniques that allow us to know the frequency and distribution of health problems related to working conditions, to reveal the cause of them, to select the priority ones and to choose the epidemiological methods and designs, constituting an elementary program of prevention and control of risks that may affect health, and consequently, the productivity and performance of each of the employees in the organization.
- - - - In general, the clinician focuses his attention on the individual, particularly on his condition as a sick person, and studies those bodily manifestations that allow him to identify the disease that afflicts him (diagnosis) in order to design a strategy that attempts to cure, stop or delay the progression of the disease (treatment). Medicine is, in Hippocratic thought, a technique and the clinician is the one who practices this technique on the subject of study (individual).
        
        Epidemiology, thus conceived, is essentially scientific research on human beings and its results are at the service of public health and clinical practice. Moreover, the research designs that clinicians carry out to contribute scientific information to their daily work (controlled clinical trials) have been generically catalogued with the suggestive name of clinical epidemiology.
        
        The methods used in the study of occupational and environmental factors are the same as those used in other branches of epidemiology. However, an important characteristic of occupational epidemiology is its relationship to a population of young adults and middle-aged persons, and often predominantly of male gender. Furthermore, in occupational epidemiology most of the exposed groups are relatively healthy, at least at the beginning of the work. This has given rise to the term "healthy worker effect" which indicates that the working population, in contact with risk factors, has a lower total morbidity and mortality than the population as a whole.
        
        In contrast, epidemiological studies of general (community) environmental factors usually include children, older people and sick people. This is of great importance when using the results of occupational epidemiology studies to establish safety standards for specific environmental hazards. Exposed persons in the general population are likely to be more sensitive than workers. For example, health effects from inorganic lead at low levels of exposure have been described more frequently in children and adult women than in adult men.
        
        Causal relationship. This consists of determining the profile of the characteristics that define the risk factors associated with an occupational disease. The associations between these characteristics and the occurrence of the disease may arise by coincidence, by non-causal links to other characteristics, or by cause and effect relationships, which will be analyzed later. The identification and characterization of risk factors provides a valid understanding of the mechanisms of action involved in disease occurrence. The occurrence of the health effect is determined not only by environmental factors, including lifestyle, but also by biological factors (cellular and genetic) of the workers.
- - - - Some biological parameters vary with the age and body constitution of the workers (weight and height), as well as with climatic factors (atmospheric pressure and climate), e.g. lung volumes. This requires establishing normal or reference values for the person or population under study, in order to compare the results obtained directly in the respiratory function tests with the reference values, and to decide on the normality or not of the test, in order to additionally take preventive and control measures based on these results.
        
        Identification and interpretation of occupational disease occurrence patterns and environmental impact. Pattern of occurrence is understood as the characteristic modality or profile in which an occupational disease usually occurs, adopting particular features for the different components of the working population. Likewise, there is usually a characteristic pattern of conditioning and/or causal factors of a particular occupational disease. The identification of the patterns of occurrence is the fundamental part of epidemiological work, since it provides information as to why some workers become ill and others do not.
        
        Prevalence and Incidence
        Epidemiology has among its primary objectives the study of the distribution and determinants of different diseases. The quantification and measurement of disease or other variables of interest are fundamental elements for formulating and testing hypotheses, as well as for comparing disease frequencies between different populations or between individuals with or without an exposure or characteristic within a given population.
        
        The most basic measure of the frequency of a disease, or of any other event in general, is the number of people who suffer from or present with it (for example, the number of patients with arterial hypertension, the number of deaths due to traffic accidents, or the number of patients with some type of cancer in whom a recurrence has been recorded). However, this measure alone is not useful for determining the importance of a given health problem, since it must always refer to the size of the population from which the cases originate and the time period in which they were identified.