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PubMed1993

Assessment of the proposed Draft American National Standard method for evaluating the effectiveness of hearing conservation programs.

Using audiometric data, this study assessed the Draft American National Standard ANSI S12.13-1991 (DANS) method for evaluating the effectiveness of hearing conservation programs by comparing it against a standard epidemiologic method. Although the hearing conservation program of the study population was rated as "acceptable" (scale: acceptable, marginal, unacceptable) using the DANS method, the epidemiologic method found a 130% increased risk of hearing loss (relative risk = 2.3, 95% confidence interval = 0.8 to 6.5). In addition, study workers who were excluded from analyses for failing to comply with the DANS criteria were found to be at significantly increased risk of hearing loss (relative risk = 9.1, 95% confidence interval = 3.4 to 24.2). These data indicate that the DANS method may overestimate the effectiveness of hearing conservation programs and systematically exclude workers at high risk of hearing loss from analyses.

Adult↗
PubMedDate not supplied

The contribution of epidemiology to psychosomatic medicine.

OBJECTIVE: To discuss the contribution of epidemiology and epidemiological methods to psychosomatic medicine. METHOD: Critical review of the literature, including both philosophical concepts and empirical data. RESULTS: The adjective "psychosomatic" has been used in two different ways: in the so called "psychosomatic" or holistic approach to medicine; and in a narrower approach, referring to particular disorders in which psychological factors were considered to have a fundamental aetiological role. While the ideal of the holistic, "humanistic" or "anthropological" approach should probably be never abandoned, the practical limitations of encompassing models, including Engel's bio-psycho-social model are also obvious: they may be heuristically sterile. On the other side, in relation to the narrow psychosomatic approach, psychogenetic views in the so called "psychosomatic illnesses" have been strongly criticized on empirical grounds. The potential of epidemiological methods to study these illnesses, but also "somatopsychic" disorders is shown in a number of papers in the empirical literature. We have grouped such contributions, including our own experience, in the five categories suggested by M. Shephered for epidemiological methods in general: 1) the completion of the spectrum of disease; 2) the establishment of outcome; 3) the actuarial assessment of morbid risk; 4) the evaluation of the efficacy of treatment; and 5) the conceptual construction of diagnosis and classification. CONCLUSIONS: The contribution of epidemiological data to areas of interest in psychosomatic medicine has been relevant in recent years. The potential of epidemiological methods in this area is very important both to increase knowledge and to improve the quality of clinical practice.

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PubMed1989

Physical activity epidemiology: concepts, methods, and applications to exercise science.

This review was conducted to provide the reader with a brief overview of the science of epidemiology as applied specifically to physical activity as a behavior. Definitions were offered for epidemiology, for physical activity, and finally for physical activity epidemiology. In addition to considering epidemiologic concepts, this review stressed the importance of carefully measuring physical activity--perhaps the principal function of anyone who ultimately claims to be a physical activity epidemiologist. The breadth and scope of physical activity epidemiology are extensive and there is fertile ground for continuing to apply physical activity epidemiology to exercise science well into the future. This chapter should provide the exercise scientist with a firm foundation to begin his or her trek into the realm of physical activity epidemiology.

Epidemiologic Methods↗
PubMed1996

Case counting in epidemiology: limitations of methods based on multiple data sources.

BACKGROUND: The application of capture-recapture methods in epidemiology has been proposed as an alternative to field surveys. This methodology is important for the future of epidemiology and deserves a critical analysis. METHODS: This paper reviews conditions for applying the capture-recapture models to epidemiological data, taking into account practical considerations, in particular the problem of case definition. RESULTS: The underlying assumptions are particularly restrictive resulting in a theoretical limitation of their applicability. In spite of the statistical developments designed to overcome these difficulties, the practical conditions for using the existing lists are often not fulfilled (availability, confidentiality). The major restriction is on the quality of the data which are often far below the standards required in specific prevalence surveys and which may differ between lists. This may result in a dramatic lack of specificity. The definition of the virtual subgroup of patients missing in all lists as generated by the statistical procedure, is questionable particularly when counting living patients. Field studies would be necessary for validation. CONCLUSIONS: In some particular situations (e.g. deceased patients, rare diseases), this methodology may provide a useful approximation to the number of ill subjects events, but users should be aware of their poor specificity. It can also be useful to complement data from surveillance systems by careful cross-checking with independent sources of information. Currently, this method cannot, in any way, replace direct population prevalence or incidence surveys.

Epidemiologic Methods↗
PubMed1988

Smoothing methods for epidemiologic analysis.

The development of techniques for fitting non-parametric smooth curves has resulted in less restrictive regression models. We discuss the ideas underlying such smoothing algorithms, develop their application to epidemiologic studies and address specific issues, such as coping with correlated errors. An example illustrates a particular smoothing approach, as applied to pulmonary function data. The method provides new insight into the effect of smoking on pulmonary function. The discussion offers some qualitative comparisons between smoothing methods and conventional linear models.

Adult↗
PubMed1989

Comparison of epidemiological marker methods for identification of Salmonella typhimurium isolates from an outbreak caused by contaminated chocolate.

Plasmid profile analysis, restriction endonuclease analysis, and multilocus enzyme electrophoresis were used in conjunction with serotyping, bacteriophage typing, and biochemical fingerprinting to trace epidemiologically related isolates of Salmonella typhimurium from an outbreak caused by contaminated chocolate products in Norway and Finland. To evaluate the efficiency of the epidemiological marker methods, isolates from the outbreak were compared with five groups of control isolates not known to be associated with the outbreak. Both plasmid profile analysis and phage typing provided further discrimination over that produced by serotyping and biochemical fingerprinting. Plasmid profile analysis and phage typing were equally reliable in differentiating the outbreak isolates from the epidemiologically unrelated controls and were significantly more effective than multilocus enzyme electrophoresis and restriction enzyme analysis of total DNA. The greatest differentiation was achieved when plasmid profile analysis and phage typing were combined to complement serotyping and biochemical fingerprinting. However, none of the methods employed, including restriction enzyme analysis of plasmid DNA, were able to distinguish the outbreak isolates from five isolates recovered in Norway and Finland over a period of years from dead passerine birds and a calf.

Animals↗
PubMedDate not supplied

[Phenotypic and genotypic methods for epidemiological typing of veterinary important bacterial pathogens of the genera Staphylococcus, Salmonella, and Pasteurella].

Molecular typing methods are capable of providing detailed strain characteristics which are commonly far beyond the capacities of phenotypic typing methods. Such molecular-based characteristics have proved to be very helpful in epidemiological studies of bacterial pathogens. The primary criteria that all typing methods should fulfill include (1) the typeability of the strains in question, (2) the reproducibility of the results, and (3) a high discriminatory power. In general, molecular typing methods can be differentiated with regard to their use in methods that can be applied to virtually all bacteria (e.g. plasmid profiling, ribotyping, macrorestriction analysis) and methods which can only be used for typing of certain bacterial genera or species (e.g. IS200 typing of certain Salmonella enterica subsp. enterica serovars, or coa-PCR of coagulase-positive staphylococci). In the present review, various phenotypic and molecular methods for the epidemiological typing of bacteria of the genera Staphylococcus, Salmonella, and Pasteurella are described and their advantages/disadvantages--also with regard to the fulfillment of the above-mentioned primary criteria--are critically assessed.

Animals↗
PubMed1977

Epidemiologic screening: a method to add efficiency to epidemiologic research.

The concept of power loss through misclassification is well known. A simple method developed here yields a means for determing by how much power is lost. The method provides the basis for the development of an efficient screening methodology for the identification of high and low risk cohorts. This screening procedure is built on the well established retrospective cohort methodology and utilizes general records of mortality and morbidity for determination of the frequency of disease in the exposed and non-exposed cohorts. The size and power of the testing procedure compare favorably to that of a study with complete follow-up, while reducing the time and costs of study. This is particularly important in aiding epidemiologists in determining research and program priorities from among many areas of possible concern.

Epidemiologic Methods↗
PubMed1991

The use of transfer function models, intervention analysis and related time series methods in epidemiology.

In epidemiology, data often arise in the form of time series e.g. notifications of diseases, entries to a hospital, mortality rates etc. are frequently collected at weekly or monthly intervals. Usual statistical methods assume that the observed data are realizations of independent random variables. However, if data which arise in a time sequence have to be analysed, it is possible that consecutive observations are dependent. In environmental epidemiology, where series such as daily concentrations of pollutants were collected and analysed, it became clear that stochastic dependence of consecutive measurements may be important. A high concentration of a pollutant today e.g. has a certain inertia i.e. a tendency to be high tomorrow as well. Since the early 1970s, time series methods, in particular ARIMA models (autoregressive integrated moving average models) which have the ability to cope with stochastic dependence of consecutive data, have become well established in such fields as industry and economics. Recently, time series methods are of increasing interest in epidemiology. Since these methods are not generally familiar to epidemiologists this article presents their basic concepts in a condensed form. This may encourage readers to consider the methods described and enable them to avoid pitfalls inherent in time series data. In particular, the following topics are discussed: Assessment of relations between time series (transfer function models). Assessment of changes of time series (intervention analysis), forecasting and some related time series methods.

Epidemiologic Methods↗
PubMed1990

[The use of different statistical methods in epidemiological analysis to assess the seasonality and territorial spread of infectious diseases].

To solve the problems connected with the evaluation of the seasonal and territorial distribution of infectious diseases, indications and limitations for the use of the following statistical methods have been worked out: the calculation of the monthly morbidity level, the proportion of cases of infectious diseases falling on the months of seasonal morbidity rises, the proportion of such cases appearing due to the influence of seasonal factors, the total and partial indices, the average monthly rate of increase in seasonal morbidity, the complex evaluation of seasonal morbidity, the evaluation of the nonparallelism of two curves, the determination of the mean quadratic deviations and Shannon's entropy. The algorithms based on these methods lie in the foundation of 11 computer programs, forming the software complex "Epidanalysis" and provided with the service menu permitting an epidemiologist to proceed from the task via indications and limitations to the corresponding program. The programs are intended for different types of computers (IBM PC XT, EC-1640, Robotron 1715).

Algorithms↗
PubMed1985

N-Nitroso compounds and human cancer. A molecular epidemiologic approach.

N-Nitroso compounds are known to be potent animal carcinogens. However, evidence of their effect on human cancers is inconclusive, and further investigations are needed. A mathematical model to create indices of nitrate, nitrite, and N-nitrosamine exposures, both exogenous and endogenous, is described in this paper. Estimation of the endogenous formation is based on the current knowledge of biochemistry and chemical kinetics of these compounds. The model can be applied to analyze data regarding the dietary history and use of tobacco products and alcoholic beverages obtained from epidemiologic questionnaires. Exposure levels of study and control subjects to these compounds can then be compared by conventional epidemiologic methods. This is an approach toward the combination of conventional epidemiologic methods and laboratory findings to study disease etiology.

Adult↗
PubMed1996

[Molecular biological methods for epidemiological typing of Salmonella--a review].

Various molecular typing methods for the analysis of zoonotic bacterial pathogens have been developed during the last decade. Because of their high discriminatory power, these methods have been increasingly used even in routine diagnostics. The description of several independent genotypic characteristics in addition to that of the phenotypic properties enables a complex and exact identification of bacterial strains. Molecular techniques such as plasmid analysis, ribotyping. IS200 typing as well as macrorestriction analysis represent components of a basic molecular typing system for Salmonella isolates which proved to be suitable for various epidemiological applications.

Animals↗