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At least 19 recordsLinked to original sources
PubMed1983

Practical limitations of epidemiologic methods.

Epidemiologic methods can be categorized into demographic studies of mortality and morbidity and observational studies that are either retrospective or prospective. Some of the limitations of demographic studies are illustrated by a review of one specific mortality study showing possible relationship of nuclear fallout to leukemia. Problems of accuracy of diagnosis or causes of death on death certificates, estimates of population, migration from areas of study, and the issue of "ecological fallacy" are discussed. Retrospective studies have such problems as recall of previous environmental exposure, selection bias and survivor bias. In environmental epidemiology, prospective studies have been used. The problems associated with these studies are illustrated by reviewing some of the details of the study of effects of microwave radiation on embassy employees in Moscow. The study population had to be reconstructed, individuals had to be located and information on exposure status had to be obtained by questionnaire. The relatively small size of the exposed group permitted the detection of only fairly large relative risks. Despite these limitations, epidemiologic studies have been remarkably productive in elucidating etiological factors. They are necessary since "the proper study of man is man."

Demography↗
PubMed2006

A hierarchical step-model for causation of bias-evaluating cancer treatment with epidemiological methods.

As epidemiological methods are used increasingly to evaluate the effects of cancer treatment, guidelines for the application of such methods in clinical research settings are necessary. Towards this end, we present a hierarchical step-model for causation of bias, which depicts a real-life study as departing from a perfect setting and proceeding step-wise towards a calculated, often adjusted, effect-parameter. Within this model, a specific error (which influences the effect-measure according to one of four sets of rules) is introduced on one (and only one) of the model's four steps. This hierarchical step-model for causation of bias identifies all sources of bias in a study, each of which depicts one or several errors which can be further categorized into one of the model's four steps. Acceptance of this model has implications for ascertaining the degree to which a study effectively evaluates the effects of cancer treatment (level of scientific evidence).

Bias↗
PubMed2003

[The genetic diversity of Mycobacterium tuberculosis and an assessment of risk factors of tuberculosis spread in Russia's Siberian region by molecular epidemiological methods].

Molecular epidemiology approaches provided for a new interpretation of the TB infection transmission dynamics, contributed to changing the focuses of attention and updated the monitoring practice. On the basis of 101 cases of isolates of Mycobacterium tuberculosis (MBT) complex sampled from 84 patients with pulmonary tuberculosis in the Siberian region, we proved that the independent methods of IS6110 RFLP genetic typing and VNTR-typing by five accurate repeat tandems of ETR A, B, C, D, and E bring about similar results and can be used in studying the MTB clonal structure population in the Siberian region for the purpose of defining the TB infection transmission dynamics. The most widespread genetic types were detected, i.e. Beeijing family strains, the S42 spoligotype, and the 31323 VNTR type, which account for 52.3% of all samples. The general parameters describing the epidemic process intensity were evaluated, i.e. those characterizing the strains (91.6%) and the transmission activity factor (72%). Consequently, each three of the four analyzed TB cases resulted from a recent transmission. However, there is a trend, within the analyzed samples, towards a higher percentage of clusterization in the age group ranging from 40 to 60. Such trend is typical of a prevalence of TB reactivation cases caused by MBT complex strains spread intensively in the discussed territory. As for the clusterized isolates, which are endemic for the territory, such data should be interpreted as a recent transmission only cautiously. 28.5% of the studied isolates are resistant to anti-TB drugs used in medical practice; and 35.7% of them are resistant to izoniazide and rifampicin, therefore, according to the WHO classification they are considered to be poly-antibiotics-resistant (PAR). No strict associations were found between the spectrum of antibiotics-resistance and any of genotypes, however, 30% of PAR strains are 32525 and 42525 types VNTR (spoligotype S1 or Beejing type).

Adult↗
PubMed1978

The use of epidemiologic methods in family practice.

Epidemiologic methods of research can be readily used in family practice. Since the 19th century, family physicians have used epidemiologic methods in making important contributions to the understanding of disease. Using these methods requires an organized practice including patient registers, encounter data, and detailed records. Descriptive studies can define certain characteristics that are related to disease. Case-control and cohort studies can provide evidence for the association of risk factors and disease. A stepwise outline for carrying out a study is presented.

Epidemiologic Methods↗
PubMed1977

Epidemiologic methods in clinical trials.

Epidemiologic methods developed to control confounding in non-experimental studies are equally applicable for experiments. In experiments, most confounding is usually controlled by random allocation of subjects to treatment groups, but randomization does not preclude confounding except for extremely large studies, the degree of confounding expected being inversely related to the size of the treatment groups. In experiments, as in non-experimental studies, the extent of confounding for each risk indicator should be assessed, and if sufficiently large, controlled. Confounding is properly assessed by comparing the unconfounded effect estimate to the crude effect estimate; a common error is to assess confounding by statistical tests of significance. Assessment of confounding involves its control as a prerequisite. Control is most readily and cogently achieved by stratification of the data, though with many factors to control simultaneously, multivariate analysis or a combination of multivariate analysis and stratification might be necessary.

Clinical Trials as Topic↗
PubMed1982

The use of epidemiologic methods as the bridge between prevention and social work practice.

The concepts, scope and methods of epidemiology as well as the application of these tools to preventive social work practice for both policy setting and case management are described. Using data concerning lead poisoning, two areas are discussed. These are: 1) the stages of prevention and its implication for practice, and 2) definitions of the epidemiologic concepts of population-at-risk, prevalence, incidence, case rate, relative risk, attributable risk, and epidemiologic causal models. Finally, suggestions for using epidemiologic knowledge and methods in formulating policy for, and programs pertaining to, prevention in social work practice are set forth.

Child↗
PubMed1991

[Epidemiological methods in evaluation].

This paper describes different epidemiological methods to evaluate the effect of a public health intervention. The different types of indicators as well as types of evaluative surveys (experimental, quasi-experimental, observational) are presented. Criteria for choosing one type of survey are discussed. Examples of surveys are described.

Cohort Studies↗
PubMed2002

Epidemiologic methods: the "art" in the state of the art.

When performing empirical research in public health and medicine, the investigator is typically faced with a variety of methodologic issues to resolve at the design and analysis stages of the research. The investigator must specify the research question, conceptualize and operationalize the variables to be measured, consider several research designs to choose from, determine appropriate measures of disease frequency and effect, address potential biases, devise the analytic strategies to follow, choose the appropriate software procedures or packages to use, carry out the analysis, and interpret the results. Most of these issues concern principles and methods of epidemiology and biostatistics, which, taken together, embody the methodologic "science" that underlies such research. Nevertheless, in bringing all these issues together to achieve a coherent and valid research conclusion, there is an "art" that is required that goes beyond the quantitative mechanics involved in carrying out the research. The art part is not easily quantifiable and typically is more skillfully performed as one becomes a more experienced investigator. Nevertheless, such methodologic art can be addressed methodologically through guidelines that identify the options or strategies available and suggest how appropriate choices can be made from such options or strategies. Selection bias and mathematical modeling are especially addressed.

Epidemiologic Studies↗
PubMed2000

Epidemiologic methods for the prevention of nosocomial infections.

There is an ongoing controversy in Europe about the benefits and limitations of epidemiologic methods for the prevention and control of hospital-acquired infections. Hospital epidemiology, aimed at measuring the necessity, or effect, of preventive strategies for nosocomial infection control, is still an unknown field in many European institutions. The conceptual framework presented here is not intended as a complete review of modern hospital epidemiology, but should be considered rather a viewpoint which tries to bridge the gap between microbiology-based hospital hygiene and hospital epidemiology in Europe. The explanatory power and limitations of descriptive, analytical and interventional epidemiology are described. Based on the assumption that nosocomial infections have causal and preventive factors that can be identified through systematic investigation, epidemiologic methods add important knowledge to reduce hospital-acquired infections.

Cross Infection↗
PubMed1996

[The epidemiological method in the field of mental health].

The role of epidemiological methods in clinical practice and research are discussed in this article. In particular, the main applications of the epidemiological approach in the field of mental health are illustrated. First, it has been possible to investigate the prevalence and incidence of mental disorders outside specialist settings (general population and primary care services); this allowed for a better definition of the spectrum of mental disorders beyond the most severe ones which are usually treated by psychiatrists. In this way, incidence and prevalence studies contributed to the identification of groups of subjects at risk for mental disorders to be provided with prevention and treatment programs. Second, data from epidemiological studies contributed to the development of classificatory systems with high reliability and validity to be used in clinical practice and research activities. Third, epidemiological data are often integral part of theories concerning the origin, course, outcome, and treatment response of disorders. Fourth, the comprehensive and longitudinal evaluation of service activity is necessary to introduce possible changes in the organization of the health care system and to allocate available resources. Finally, it is recommended that epidemiological research could maintain a real integration with clinical practice and develop a strong collaboration with other disciplines such as genetics, psychology, sociology and anthropology.

Epidemiologic Methods↗
PubMed1982

Epidemiology and epidemiologic methods: an introduction for respiratory care practitioners.

Epidemiology is the study of the distribution of disease in a population and of the factors that determine that distribution. Respiratory care practitioners encounter many aspects of epidemiology in training and practice and should become aware that most initial epidemiologic observations are made by clinicians. The determinations that excessive oxygen administration caused retrolental fibroplasia and that exposure to cotton bracts in the textile industry caused byssinosis resulted from the collaborative efforts of epidemiologists, laboratory workers, and clinicians. The three types of study designs in observational epidemiology are: (1) the cohort (incidence) study, in which a study factor is observed at the onset of the study and the study population is followed over time for the development of new cases of a disease; (2) the cross-sectional (prevalence) study, in which the presence or absence of risk factors is measured at one point in time in a study population and prevalence rates of disease among those with and without the risk factors are compared; and (3) the case-control study, in which the numbers of persons with and without a given disease who share certain background characteristics or exposure levels to risk factors are determined and compared. The epidemiologist's continued collaboration with the clinician and the laboratory scientist is important because epidemiology alone can rarely provide conclusive solutions to every aspect of a problem.

Epidemiologic Methods↗
PubMed1985

Interactions between opposite-sex dizygotic fetuses and the assumptions of Weinberg difference method epidemiology.

The Weinberg difference method in twin epidemiology may be subject to a major error related to a fundamental assumption that seems not to have been previously questioned. Results presented here indicate that the mortality of like-sex dizygotics (DZs) resembles that of monozygotics (MZs) much more than that of unlike-sex DZs, who are not representative of any other group. Unlike-sex twins enjoy a relative protection from fetal and neonatal mortality and probably from at least one effect of the transient perinatal hypoxia common for second twins. Unlike-sex twins develop, and maintain into adulthood, an intermediate gender phenotype with respect to integration of craniofacial growth.

Birth Order↗
PubMedDate not supplied

[Evolution of epidemiological methods in clinical research in Spain (1975-1994)].

BACKGROUND: Previous studies have shown a sparing utilization of analytical and experimental designs in Spanish clinical research journals. The study aims are to compare among countries, the use of epidemiologic method in articles published in scientific journals, and to determine the extent to which this research has direct funding. METHODS: Cross-sectional study including all original papers published during 1994 in Medicina Clinica [(Med Clin (Barc)], Revista Clinica Española (Rev Clin Esp), The Lancet (Lancet) and New England Journal of Medicine (N Engl J Med). They were classified according to epidemiological design and we verified the financial support mention. RESULTS: 594 papers were included. Epidemiological studies without control group prevailed in Spanish journals. The most common designs were descriptive studies in Med Clin (Barc), with 45.5%, and clinical series in Rev Clin Esp, with 41.7%. The 33.6% of original papers published in Lancet and 28.4% of N England J Med were randomized trials. We found information about financial support in 73.7% of papers published in Lancet, in 77.4% of N Engl J Med, in 23.1% of Med Clin (Barc) papers and not one in the Rev Clin Esp studies. CONCLUSIONS: In Spanish clinical journals the use of epidemiological methods with control group is limited and direct financial support unusual. Wherefore these studies have a limited applicability.

Epidemiologic Methods↗