[Methodology and methods in epidemiology].
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Epidemiological research of partial secondary adentia was done by means of telephone interviewing the population of city of Samara (1104 persons are interrogated). Prevalence and intensity of the disease in various age groups, and also average indices for all adult population are established. The share of the persons requiring for dental prosthetics among patients with defects of dental lines is determined. The same method investigates awareness of the population about dental implantation, and also the estimation is given to public opinion on treatment with the use of implants.
Different dietary methods have been used for epidemiologic studies on nutrition, diet and disease. Methods so far reported are classified into dietary record method (including weighing method), recall method, Burke's method, frequency method, and semiquantitative frequency method. The recall method and frequency method are considered to be unsuitable when the average intake of nutrients and foods of individuals is to be assessed. It is difficult for a person to recall food intake over several days, and the 24-hour recall method is unable to evaluate the average intake. Quantitative assessment of intake is hardly possible in the frequency method. Dietary evaluation in case-control studies has limitations in terms of difficulties in retrospective dietary assessment and the change in dietary habit over a long period of time. Current epidemiologic knowledge on diet and disease stimulates cohort studies using the 7-day dietary record or semiquantitive frequency method.
Epidemiologic principles and methods have been widely employed in clinical research. The purpose of this paper is to discuss basic epidemiological concepts applied to the investigation of the determinants of infant diseases. The theoretical framework outlines the hypothesis of the investigation. The design of the study is chosen accordingly. Exposure and outcome are defined, and the sampling criteria and the strategies for its implementation are specified. The researcher can be an observer (as in cross-sectional, cohort and case-control studies) or can determine who will be exposed in the experimental studies (clinical trials). Cross-sectional study is the easiest one to conduct, since exposure and outcome are assessed simultaneously in a well-defined population. In a cohort study, a group of people is assembled according to the exposure and followed over time to detect who will develop the outcome. In a case-control study,people are selected based on disease status. Then, they are investigated about previous exposures which could be associated with the development of the disease. The investigator allocates the exposure and then follows the participants to assess the outcome in clinical trials. Contrasting with the experiment developed in laboratory, the subjects are human beings.
Multistage identification, an epidemiological screening method of diagnostic assessment, was used to identify attention-deficit hyperactivity disorder (ADHD) in 1,490 elementary-school students. Children diagnosed with ADHD exhibited more impairment on adjustment measures and were more likely to have coexisting disruptive behavior disorders than were children diagnosed as subclinical non-ADHD.
Three methods of estimating group and individual dietary consumption have been developed and assessed in a case-control study of diet and breast cancer. The methods comprised a 24-hour recall, a detailed quantitative diet history directed to the most recent two-month period and the two-month period six months before, and a four-day diet diary. There is a high degree of correlation between the estimates of food consumption for the controls using each of the methods. The highest estimate was obtained from the diet history, with a slightly higher estimate in the period six months before than the current period, while the lowest is found in the 24-hour recall. The latter corresponds with the same method in a Nutrition Canada Survey. It is concluded that all methods ara applicable to case-control studies, but the diet history is preferred when current food intake may be influenced by a disease.
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Epidemiologic methods used to study human diseases are often unfamiliar to the laboratory scientist. This paper outlines the standard method by which epidemiologic studies are classified, explains the methodologic strengths and weaknesses of different kinds of studies, and notes the kinds of inferences that can be drawn from each. Surveys on populations are treated first, followed by sample surveys. Prospective (follow-up) studies, in which groups of subjects are followed in time, are a basic epidemiologic method. Alternatives to these studies that do not require similar time commitments but may allow similar inferences are record studies. Retrospective, or case-control studies, are often the only feasible method for studying rare diseases. However, diseases with long latency periods and problems in control selection can make these studies difficult to analyze and interpret.
INTRODUCTION: The incidence of dengue (serum type I) in the city of S. José do Rio Preto during an epidemic which occurred in the first semester of 1995 is analyzed in terms of geographical areas defined by socioeconomic variables. MATERIAL AND METHOD: The epidemiological method of analysis is the "ecological study" type. To calculate the coefficient of incidence of dengue, all cases both confirmed and reported between January and July, 1995 are considered. The environmental units are defined according to socioeconomic variables based on the IBGE (Brazilian Institute of Geography and Statistics) Census of 1991, through cluster analysis. The linear correlation coefficient between coefficient of incidence and environmental variables is also calculated. RESULTS AND DISCUSSION: Three distinct environmental units are identified and described on the basis of both economic and educational level. The coefficient of incidence of dengue varied in accordance with the environmental unit: in the unit of low standard the coefficient was 2.7 times greater than that of the unit of highest standard, showing that in these units the determining factors of dengue have a differentiating effect. The roles of some of the determining factors such as population density, basic sanitary services and vector density are discussed. The importance of this study for the control of dengue is also emphasized.
'Multiple causation' is the canon of contemporary epidemiology, and its metaphor and model is the 'web of causation.' First articulated in a 1960 U.S. epidemiology textbook, the 'web' remains a widely accepted but poorly elaborated model, reflecting in part the contemporary stress on epidemiologic methods over epidemiologic theories of disease causation. This essay discusses the origins, features, and problems of the 'web,' including its hidden reliance upon the framework of biomedical individualism to guide the choice of factors incorporated in the 'web.' Posing the question of the whereabouts of the putative 'spider,' the author examines several contemporary approaches to epidemiologic theory, including those which stress biological evolution and adaptation and those which emphasize the social production of disease. To better integrate biologic and social understandings of current and changing population patterns of health and disease, the essay proposes an ecosocial framework for developing epidemiologic theory. Features of this alternative approach are discussed, a preliminary image is offered, and debate is encouraged.