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Results for “Epidemiologic Methods”

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PubMedDate not supplied

[Epidemiology of impotence. A review of methodological problems in the prevalence and risk estimation].

The aim of this paper is to analyze important methodological questions in estimates of the prevalence and risk factors in erection disorders. Sampling problems, lack of standardization in epidemiological and clinical data recording, nosographic uncertainties, explain the wide variability of prevalence estimates (2-10%). Lack of standard epidemiological methods produces differences in risk estimates of reviewed factors.

Adult↗

PubMed1976

Priorities in the investigation of human health hazards in the plastics and synthetic rubber industries.

Experiences in the past decade provide guidance in selecting priorities for investigation of health hazards in chemical industries. Pride of place should be given to the experience of large industrial populations, in part simply because large numbers of people are at risk and in part because such studies are more likely to give reliable answers. This recommendation has further strength when there is community exposure as well. Parenthetically, large populations provide opportunity to study multiple factor interaction; without this, toxic potential of a single agent may be obscured. Second, investigations should be mounted when there is reason for suspicion, as with particular chemical configurations, observed organ toxicity, animal carcinogenicity, unusual clinical experience ("signal" tumors). It may be added that when agents have already been used several decades, evaluation of human experience with them is now in order, if only to document absence of toxicity. The same recommendations hold for planned introduction of new agents or widened distribution of existing ones, until we have better information concerning validity of "pretesting" programs. Major advances have been made in epidemiological methods for these investigations. These now allow us to successfully focus on small defined groups as well as to manage large populations.

Animals↗

PubMed1975

Epidemiological studies of life change and illness.

Currently popular methodologies in life changes and illness research are presented in some detail. Selected examples of epidemiological studies utilizing these methodololgies are briefly reviewed. Examples of both retrospective and prospective investigations of life change and illness are given. Discussed in the chapter are the author's views as to limitations of the epidemiologic method and probable directions of future research in efforts to clarify etiologic mechanisms along the pathway between subjects' recent life changes and their subsequent susceptibility to illness.

Coronary Disease↗

PubMed1987

Modulation of gastric carcinogenesis: updated model based on intragastric nitrosation.

The etiological model of gastric carcinogenesis is discussed. Its complexity and flexibility may be more applicable to human situations than experimental models utilizing high doses of carcinogens in homogeneous animal populations. The limitations of the epidemiological method and the use of a collaborative approach by epidemiologists and experimentalists are described. The need for markers of exposure to N-nitroso compounds is stressed.

Animals↗

PubMed1982

An epidemiologic study of the benefits and risks of running.

To better estimate rates of certain benefits and risks of recreational running, we sent questionnaires to 1,250 randomly selected male and 1,250 female registrants for a 10-km road race. The response rate was 55% for men and 58% for women. Telephone interviews of a randomly selected group of nonrespondents indicated that the only significant differences between respondents and nonrespondents were that (1) respondents were older than nonrespondents, (2) more male nonrespondents had stopped running during the year after the race, and (3) more male nonrespondents had been hit by thrown objects. One year after the race, 89% of male and 79% of female respondents were still running regularly. Eighty-one percent of men and 75% of women who smoked cigarettes when they began running had stopped smoking after beginning recreational running. Giving up smoking was significantly more common for current runners than for "retired" runners. Weight loss was commonly associated with running and was greater in those persons who were overweight when they began running. More than a third of respondents had a musculoskeletal injury attributed to running in the year after the race and about one seventh of all respondents sought medical consultation for their injury. The risk of injury increased with increasing weekly mileage. This study uses epidemiologic methods to quantify some of the benefits and risks of running.

Accidents↗

PubMed1983

[Methodological approach to human iatrogenic cancers].

Epidemiological methods in iatrogenic cancers do not differ from those used in cancers from other etiology. Two approaches have to be associated in an order related to the novelty of the treatment already studied: --on one hand in vitro or in vivo experimentation (either tests of mutagenicity or carcinogenicity); --on the other, epidemiological surveys, what ever their types (prospective sample, exposed/non exposed, case-control ...). These two approaches must converge to provide sufficient evidence about the causal relationship between treatment and cancer.

Epidemiologic Methods↗

PubMed1994

The importance of social interaction: a new perspective on social epidemiology, social risk factors, and health.

Social epidemiology research has provided persuasive evidence of the link between the social environment--especially socioeconomic status--and health outcomes, but has failed to identify underlying mechanisms that might account for the association. The research may have been limited to date by its reliance on traditional epidemiological methods that emphasize a search for specific causal factor-disease relationships. It is time to take the research evidence and recast it to find practical solutions. We argue that the human development perspective supplies a framework for understanding the critical interaction between elements of social environment and health: Analyzing the social epidemiological research from this perspective can help to explain why and how the most potent factor, socioeconomic status, affects health outcomes. Equally important, this alternative perspective also presents health education practice implications.

Epidemiologic Methods↗

PubMedDate not supplied

Using patterns of child growth and development to assess communitywide effects of low-level exposure to toxic materials.

Child growth is a low tech method for assessing a socially valued health outcome, and its assessment focuses attention on the early portion of the lifespan. It is easily measured and sensitive to a variety of influences including chemical ones. As summary measure of health, it does not signify that a particular chemical is present, but it is a response to a variety of them. When used in conjunction with other epidemiologic methods, child growth assessment constitutes a practical, socially meaningful and biologically reasonable tool to assess the impact on community health and well being of chronic low-level exposures to toxic materials.

Child↗

PubMed1975

Complex surveillance of Streptococcus pyogenes. I. Immunological surveys of anti-M antibodies and possibilities of long-term epidemiological prognosis.

The results of complex surveillance of Streptococcus pyogenes, based on mass infections in the Czechoslovak army over a period of 11 years, are submitted. The epidemiological method revealed an incidence of cycles, lasting several years, of predominant pairs of T types, most of which could not be typed by their M protein. Auxiliary immunological surveys allowed the biological M activity of widespread strains to be estimated and probably form a basis for considerations on a negative long-term epidemiological type prognosis. The preliminary results presented offer prospects for a realistic methodological approach to the question of the type content of a future antistreptococcal vaccine.

Antibodies, Bacterial↗

PubMed1995

Accuracy of diagnostic methods used for epidemiological studies of Helicobacter pylori.

Epidemiological studies involve groups of individuals, or whole populations, many or most of whom are not ill. Clinical investigation has an individual perspective and precise statements need to be made about the individual alone. Serological methods are most commonly used for population-based epidemiological studies. Non-invasive epidemiological methods, using breath tests or the study of saliva or urine, are increasing in use. All methods depend on accuracy in identifying presently infected or non-infected persons, and accuracy in defining a previously infected person. The performance of serological methods varies with the antigens chosen, the population from which reference sera are drawn, age, ethnicity, and homologous and heterologous infection rates in the population being studied. Much of the standardization of epidemiological assays has been done in adults, which means that for children there is still uncertainty concerning standards and cut-off values. Because of differences in strains of H. pylori in different geographical areas, antigen selection is important when geographical comparisons are made. The sensitivity and specificity of a test is not strongly affected by the prevalence of infection. However, as the prevalence rises in the tested populations, the reported positive predictive value rises, and the negative predictive value falls. Depending on the patient population studied, accuracy varies with changes in the prevalence, and its magnitude depends both on the sensitivity and specificity. Accuracy is therefore not a very useful measure. It is better to look at the sensitivity and specificity, and the prevalence in the study, where they are measured. An alternative to separating test results into two or three categories is to report likelihood ratios, which report the probability of a person with a particular result being truly positive compared with the probability of a person with that result being truly negative. A receiver operating characteristic (ROC) curve, which describes the effect of varying the cut-off value on the performance of a test, can be useful in comparing the performance of two or more different tests. The use of multiple tests to augment positive culture as a 'gold standard', has been aided by use of polymerase chain reactions and other molecular biological methods. However, this augmentation has its limitations, since each of the additional methods may produce false positives. For example, polymerase chain reactions can be falsely positive if instruments are contaminated. There are people with more than one strain of Helicobacter pylori in the stomach, and, without molecular biological efforts, or serological typing tests, the 'gold standard' does not deal with multiple infections.

Helicobacter Infections↗

PubMed2001

Alzheimer's disease: insights from epidemiology.

While a complete understanding of the pathogenesis of Alzheimer's disease (AD) remains elusive, many conclusions can be drawn from the numerous epidemiological studies undertaken to date. Prevalence and incidence estimates show consistency, following a roughly exponential pattern with a doubling of both parameters roughly every five years after age 65. Roughly 7% of the population aged 65 and over has AD. The clinical course of the disease is reasonably well established and mortality rates rise with increasing levels of cognitive deficit. Four risk factors for AD are firmly established: increasing age, the presence of the apolipoproteinE-epsilon4 allele, familial aggregation of cases, and Down's syndrome. Numerous other associations have been shown in some studies, but not in others. For example, women generally appear at higher risk than men, as do people with lower levels of education; depression is probably prodromal; head injury is an established risk factor, and may interact with the apoE gene; several occupational exposures appear hazardous, and exposure to aluminum in the water supply confers excess risk. Hypertension and other vascular symptoms appear to predispose to AD, which is now seen as nosologically closer to vascular dementia than was previously believed. Several apparently protective factors have been identified, although preventive trials based on these have so far shown minimal effectiveness. The use of non-steroidal anti-inflammatory drugs to treat arthritis is associated with a reduced risk of AD, as is estrogen use by post-menopausal women. Physical activity appears beneficial, as does a diet with high levels of vitamins B6, B12 and folate. while red wine in moderate quantities appears protective. This review concludes with a discussion of the strengths and limitations of current epidemiological methods for studying Alzheimer's disease.

Age Factors↗

PubMed1986

Prosthetic epidemiology.

The need for an epidemiological method which focuses upon the problems of missing teeth, tooth spaces and prosthetic treatment is emphasized. From the prosthetic viewpoint the distinction between missing teeth and tooth spaces must be made and examples are given to show that up to 20 per cent of missing teeth do not give rise to tooth space. The presentation of the prosthetic parameters per tooth is recommended using the six alternatives: tooth present; tooth missing (open space); tooth missing (closed space); tooth replaced by pontic in fixed bridge, by removable partial denture, or by complete denture. In the presentation of the mean number of existing teeth, fixed bridge pontics should be included as they serve as natural teeth both aesthetically and functionally. Data on removable dentures, or edentulism without denture wearing, should be presented in such a way that comparisons at jaw level as well as at person level can be made. A system for this is described. The method may be used in industrialized countries where there is much prosthetic treatment as well as in developing countries with few health services. Comparisons will still be meaningful.

Adult↗

PubMed1979

The importance of epidemiology in the study of causes of bone tumours.

Research into the causes of disease in human populations makes use of epidemiological methods for recognizing avoidable risk factors which may be active prior to the occurrence of malignant tumours. With the exception of the risks or irradiation, the aetiology of bone tumours remains unclear, and it is particularly striking that in the literature to date and in a survey of research currently in progress there are no epidemiological studies which involve other than radiation-exposed populations. This is the reason why it has only been possible to obtain initial suggestions of potential areas of risk from ecologic correlations based on the evaluation of mortality and morbidity rates with respect to environmental factors. Several results obtained from systematic comparisons of mortality in the countries of the world and two correlative relationships are reported, and the difficulties in interpreting the results are discussed. Population-based registration of bone tumours and case-control studies based on registries are recommended.

Adolescent↗

PubMed2006

[Epidemiological studies in the HTA evaluation process].

Results of epidemiological studies should be considered as part of the available evidence when evaluating drug treatment benefits in health technology assessment (HTA). Pharmaco-epidemiological databases can provide a broader understanding of the effectiveness of drugs in populations that are frequently underrepresented in clinical trials. Such databases are also useful to investigate drug safety with regard to socio-demographic and medical care-related indicators and hereby contribute to an optimal and targeted pharmacological therapy. Using examples from pharmaco-epidemiological asthma studies, the present article discusses associated difficulties in interpreting database results against the background of various sources of bias and proposes possibilities for integrating observational data into the HTA evaluation process. Researchers are challenged to engage in considerable efforts to develop a standardized inventory of epidemiological methods, e.g. for the pooled analysis of epidemiological data.

Biomedical Technology↗

PubMed2001

Emotional isolation: prevalence and the effect on well-being among 50-80-year-old prostate cancer patients.

OBJECTIVE: To investigate to what extent prostate cancer patients confide their emotional concerns, and whether having no one to confide in affects well-being. MATERIAL AND METHODS: A population-based study using epidemiological methods. A questionnaire was mailed to all 431 living prostate cancer patients aged 50-80 at the time of selection, diagnosed 1.5-2 years previously in Stockholm County, and 435 randomly selected men in the same age group. The questionnaire was completed anonymously. The main outcome measures included questions assessing the extent to which the men could share emotionally taxing feelings with their partner or others and questions assessing well-being. RESULTS: The questionnaire was returned by 79% of the patients and by 73% of the randomly selected men. Approximately one in five patients had no one to confide in. Of patients living with a partner, only one in 10 confided in someone other than their partner. Three out of 10 patients living in a relationship could not confide in their partner. Men having no one to confide in were less content with their life and reported poorer psychological and overall well-being compared with other men. The prostate cancer patients were not more likely to have someone to confide in than men in general. CONCLUSIONS: The results indicate that a lack of emotional support may be a problem for many prostate cancer patients and that the traditional psychosocial support offered to most cancer patients in Sweden may not reach male patients. There may be a need for a gender-adapted approach to emotional support.

Aged↗

PubMed1988

Carcinogenicity of chemicals: the weight of evidence.

1. The evidence discussed here is derived from epidemiology, long-term bioassays in laboratory animals, and predictive short-term tests. 2. Epidemiological data are obtained directly from human studies and are most compelling when they demonstrate a large relative risk and a clear dose-response in association with a distinctive tumour type. Exposure to a suspected carcinogen and the doses involved are, however, often difficult to determine, and the most sophisticated epidemiological methods are relatively insensitive. There are no epidemiological data for most occupational/environmental chemicals. 3. Long-term bioassays can present major problems in design, interpretation and extrapolation. Particular difficulties are associated with the planning of appropriate dose levels and the occurrence of certain tumours at high incidence in both control and test groups. Results from animal bioassays set priorities for concern and action but they cannot be reliably used for quantitative assessment of human risk. 4. Evidence of potential carcinogenicity derived from short-term predictive tests, involving a wide variety of systems with diverse end-points, is increasingly important. Emphasis is placed on the need for more in vivo procedures with a broadening of the scope of somatic cell targets.

Animals↗

PubMed2005

[Correspondence analysis on random amplified polymorphic DNA genotyping and drug-resistance of Neisseria gonorrhoeae strains in Pudong area, Shanghai].

OBJECTIVE: Using molecular epidemiology methods to investigate relationship between genotypes and drug-resistance of neisseria (N.) gonorrhoeae in Shanghai area. METHODS: A random amplified polymorphic DNA (RAPD) fingerprint method at the molecular level was used to differentiate the strains which were isolated from the outpatients of sexually transmitted disease clinics. The sensitivity to antibiotic of the 78 N. gonorrhoeae strains on 9 different antibiotics was tested and the relationship between different genotypes and phenotypes was studied. RESULTS: Selected RAPD primer could give out a group of amplification polymerase chain reaction bands with some main segments common to all the N. gonorrhoeae strains tested and some segments were different among the N. gonorrhoeae strains. All the 78 N. gonorrhoeae strains could be classified as three different groups (I, II and III). The strains could also be distinguished as four types (A, B, C and D) according to drug-resistance status. Using correspondence analysis method, the relationship between the three genotypes and four resistance types could be identified. CONCLUSION: RAPD fingerprint seemed a useful genotyping method and could be used for molecular epidemiological studies.

Adolescent↗

PubMed1988

Hemoglobin adducts of aromatic amines: associations with smoking status and type of tobacco.

Hemoglobin adducts of 15 aromatic amines were determined in nonsmokers and smokers of blond- or black-tobacco cigarettes living in Turin, Italy. The subjects were all males age 55 or less and were representative of the population previously examined in a case/control study of bladder cancer. 4-Aminobiphenyl adduct levels were found to be significantly different in the three groups, and the differences were approximately proportional to the relative risk of each group. Adjustment for age and cigarette consumption did not materially influence the differences. A significant correlation of adduct levels with cigarette consumption was also observed for all smokers as well as for smokers of blond tobacco. Other amines for which significant differences between smokers and nonsmokers were observed were 3-aminobiphenyl, 2-naphthylamine, o- and p-toluidine, 2,4-dimethylaniline, and 2-ethylaniline. Some of these amines are human bladder carcinogens, and their occurrence in blood as hemoglobin adducts is evidence for their metabolic activation. Thus, by a combination of traditional epidemiological methods and modern chemical analyses, we have provided evidence for a biochemical basis for the often observed association between cigarette smoking and bladder cancer.

Adult↗