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Results for “Epidemiologic methods”

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PubMed1993

Complex mixtures and indoor air pollution: overview of epidemiologic methods.

The likelihood of an epidemiologic study correctly identifying an adverse health outcome associated with exposure to indoor air pollutants is increased if a) substantial variation exists in the frequency or level of exposure among study subjects otherwise at similar risk of the health outcome; b) the number of study subjects or study communities is large; c) the health outcome can be assessed with accuracy; d) relevant exposure levels can be measured with accuracy; e) an unbiased sample of exposed and nonexposed subjects is selected for study; and f) other determinants of the adverse health outcome can be measured. Nonetheless, given a strong enough impact of exposure to one pollutant or a mixture of pollutants on the risk of illness, it is possible for epidemiologic studies to discern a relation even if only some of the above circumstances are present.

Air Pollution, Indoor↗
PubMed1988

What can epidemiological methods mean to surgical research?

Traditionally, the aim of epidemiological research has been to determine and explain the incidence of a disease and thereby ultimately to reveal its causative mechanisms. Clinical research, or clinical epidemiology, on the other hand, has been devoted primarily to the evaluation of diagnostic and therapeutic techniques and to investigation of the course of a disease after its diagnosis. The aim of this brief discussion is to illustrate how these two areas of research--epidemiological and clinical--have the same methodological roots and use similar biostatistical tools. Whether they are carried out as experimental or as observational studies, the fundamental problem in the scientific method is to achieve validity by attenuating or controlling the effects of extraneous factors that influence the outcome under study. In modern epidemiology powerful methods of reaching this goal have been developed and thus a sound basis has been provided for drawing reliable conclusions concerning causal relations between "exposures" and outcomes. If surgical researchers become aware that epidemiological and clinical researchers obtain their scientific tools from the same conceptual domain and become familiar with the methods used in traditional epidemiology, this will probably result in fruitful scientific expansion in clinical surgery.

Clinical Trials as Topic↗
PubMed1991

Epidemiological methods for investigating wild animal reservoirs of animal disease.

The epidemiological and ecological methodologies used to investigate tuberculosis in badgers (Meles meles) in Great Britain are reviewed. The objectives of these studies have been, on the one hand, to investigate the causal association between Mycobacterium bovis infection in badgers and the occurrence of tuberculosis in cattle and, on the other, to acquire knowledge of the population biology of badgers and the dynamics of infection in order to identify, formulate and assess potential strategies. The studies provide examples of the possible approaches and the practical difficulties that investigations of wild animal populations present; the importance of a multi-disciplinary team which can be maintained for the protracted periods necessary for prospective studies is also highlighted. The most successful components of the research programme have been specific prospective studies of populations, as they provide the only means of understanding the dynamic aspects of the population biology and the epidemiology of infection and disease. Expedient, cross-sectional studies have, however, proved valuable in supplementing the main long-term studies.

Animal Diseases↗
PubMed1993

Epidemiologic methods in mastitis treatment and control.

Methods and concepts of epidemiology offer means whereby udder health can be monitored and evaluated. Prerequisite to a sound epidemiologic approach is development of measures of mastitis that minimize biases and that account for sensitivity and specificity of diagnostic tests. Mastitis surveillance offers an ongoing and passive system for evaluation of udder health, whereas clinical and observational trials offer a more proactive and developmental approach to improving udder health.

Animals↗
PubMed2004

Evolution of epidemiologic methods and concepts in selected textbooks of the 20th century.

Textbooks are an expression of the state of development of a discipline at a given moment in time. By reviewing eight epidemiology textbooks published over the course of a century, we have attempted to trace the evolution of five epidemiologic concepts and methods: study design (cohort studies and case-control studies), confounding, bias, interaction and causal inference. Overall, these eight textbooks can be grouped into three generations. Greenwood (1935) and Hill (first edition 1937; version reviewed 1961)'s textbooks belong to the first generation, "early epidemiology", which comprise early definitions of bias and confounding. The second generation, "classic epidemiology", represented by the textbooks of Morris (first edition 1957; version reviewed 1964), MacMahon & Pugh (first edition 1960; version reviewed 1970), Susser (1973), and Lilienfeld & Lilienfeld (first edition 1976; version reviewed 1980), clarifies the properties of cohort and case-control study designs and the theory of disease causation. Miettinen (1985) and Rothman (1986)'s textbooks belong to a third generation, "modern epidemiology", presenting an integrated perspective on study designs and their measures of outcome, as well as distinguishing and formalizing the concepts of confounding and interaction. Our review demonstrates that epidemiology, as a scientific discipline, is in constant evolution and transformation. It is likely that new methodological tools, able to assess the complexity of the causes of human health, will be proposed in future generations of textbooks.

Epidemiologic Methods↗
PubMed1986

Evaluation of the Singh index and femoral calcar width as epidemiological methods for measuring bone mass in the femoral neck.

Epidemiological research into the causes of osteoporosis requires a validated radiological measure of bone mass. Ashing studies were carried out on 62 excised femoral heads, and a positive correlation was demonstrated between the weight to volume ratio of the ash and two radiological indices in the contralateral femoral neck: the Singh grade and the femoral calcar width. The repeatability and right-left concordance of the Singh grading method was also assessed. It is concluded that these radiological indices will provide useful epidemiological tools for the measurement of bone mass in the proximal femur.

Aged↗