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Results for “Epidemiologic Methods”

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PubMed1989

[Epidemiologic criteria for the evaluation of positive and negative effects of the administration of high doses of vitamins].

Epidemiological methods can provide evidence, not proof, of cause effect relationships. They can confirm and quantify the existence of statistical relationships. Causality in epidemiological terms means that such relationships are strong and stable enough to enable the change of the suspected effect by changing the suspected cause. Criteria for epidemiological evidence of effects of elevated dosages of vitamins are basically the same as those for the evidence of effects of other exposures. Given the unambiguous classifications of both exposure and cases, they comprise strength, significance, specificity and consistency of the statistical association, plausible time relationships as well as dose effect relationship and consistency with other evidence. Epidemiological evidence for beneficial or detrimental effect of elevated vitamin doses may be derived from experimental or observational studies. It may confirm effects extrapolated from much higher exposure or from animal models. Today the term epidemiological evidence usually refers to field experience often to "observational", i.e. non-experimental evidence. Here comparison groups may not come from the same source populations and many confounding variables can only be controlled by sophisticated statistical procedures. A typical example for this are the so-called "ecological studies". They are frequently criticized because of their potential for exaggerated interpretations but they can be very helpful in constructing and supporting hypotheses. For very rare, and long term effects the description and evaluation of individual cases are often combined with attempts of quantification by relating them to the estimated exposure of the source population. This is subject to numerous sources of errors.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-Response Relationship, Drug↗

PubMed1988

Disease outbreak investigations--objectives, methods and importance.

In South Africa approximately 100 disease outbreaks or epidemics requiring investigation and control can be anticipated each year. Outbreak investigations play a critical role in determining effective disease control strategies. The application of modern epidemiological methods to the study of disease outbreaks is discussed and problem-solving methodology, which has similarities to the approach used in clinical diagnostics, described. These methods were applied to the investigation of an outbreak of Legionnaire's disease at a Johannesburg teaching hospital.

Disease Outbreaks↗

PubMed1988

Benefits and risks of running among women: an epidemiologic study.

To describe some of the suggested health benefits and risks of regular running in young and middle-aged women, a group of 428 Swiss female contestants in a popular 16-km race was studied by questionnaire (response rate 86%). The estimated endurance estimate capacity of female runners (VO2max equivalents, based on 16-km running time) was superior to the endurance capacity of both the female and the male general population. The strongest predictor of runners' VO2max was habitual weekly training distance. Training and life-style characteristics of the contestants were able to explain part of, but not the whole, difference in VO2max seen between runners and women of the general population. Running activity was positively associated with reported weight loss and quitting smoking. However, during the year preceding the race, 40% of the female contestants sustained running-related injuries or complaints, 17% sought medical help therefore, and 14% had to interrupt running for 6 weeks on average. Sites and types of running injuries showed specific female properties. Female runners had significantly less outpatient physician visits than the general population, but among runners the highly active (greater than or equal to 25 km/week) had more visits than the moderately active (less than 25 km/week), due to excess consultations because of running-related complaints. This cross-section study used epidemiologic methods to quantify some benefits and risks of running.

Adolescent↗

PubMed2001

[Preliminary study on the methods of systematizing the data of ancient epidemic situations].

Taking the data of ancient epidemic situations in the south of the Five Ridges, as an example, the systematization materials of ancient epidemic situation guided by epidemiological methods are explored by defining the material of epidemic situation, selected compilation of relevant factors, decision of the severity, location, and its occasion etc. It is attempted to solve some problems in modernization and datalization of the collation of ancient literatures of Traditional Chinese Medicine.

China↗

PubMed2005

[Smoking as potential confounder in german epidemiological studies: standardization of assessment, quantification, and analysis].

Tobacco smoking is one of the most frequently examined risk factors in epidemiological studies due to the high frequency of smoking in the population and its high risk potential. This paper discusses the issue of standardization of the assessment of tobacco exposure in German epidemiological studies based on a suggestion of the working group "Epidemiological methods" of the German Society of Epidemiology (DGEpi), the German Society of Social Medicine and Prevention (DGSMP), and German Society of Medical Informatics, Biometry and Epidemiology (GMDS) together with the working group "Epidemiology in the workplace" of the DGEpi and the German Society of Occupational and Environmental Medicine (DGAUM). The main element is a short questionnaire for German adults for the assessment of tobacco smoking in epidemiological studies where smoking is a potential confounder. In addition, information on the consideration of intermittent periods of non-smoking, a very short questionnaire for medical examinations in the workplace or non-responder interviews as well as the quantification and statistical modelling of smoking are presented. A brief discussion of scientific problems and questionnaires related to the exposure to environmental tobacco smoke is given.

Bias↗

PubMed2004

Occurrence of respiratory virus: time, place and person.

BACKGROUND: Respiratory viruses account for most respiratory infections. Although analysis of epidemiologic information regarding viral seasonality, sites of transmission and susceptible populations is essential to devising strategies for limiting epidemics, few long term epidemiologic studies have addressed these questions. METHODS: Epidemiologic findings identifying susceptible populations, as well as temporal and geographic patterns of infection with influenza virus, respiratory syncytial virus, rhinovirus and parainfluenza virus were reviewed. CONCLUSIONS: Influenza is the virus most frequently associated with outbreaks of respiratory infection resulting in medical consultation as well as virus-related lethality. Similar symptom profiles and overlapping seasonality of respiratory syncytial virus and other viruses may sometimes complicate surveillance and treatment. Although vaccination and antiviral drugs are virus-specific, factors that promote transmission and thus strategies for limiting outbreaks are similar for various respiratory viruses.

Adolescent↗

PubMed1998

Klebsiella spp. as nosocomial pathogens: epidemiology, taxonomy, typing methods, and pathogenicity factors.

Bacteria belonging to the genus Klebsiella frequently cause human nosocomial infections. In particular, the medically most important Klebsiella species, Klebsiella pneumoniae, accounts for a significant proportion of hospital-acquired urinary tract infections, pneumonia, septicemias, and soft tissue infections. The principal pathogenic reservoirs for transmission of Klebsiella are the gastrointestinal tract and the hands of hospital personnel. Because of their ability to spread rapidly in the hospital environment, these bacteria tend to cause nosocomial outbreaks. Hospital outbreaks of multidrug-resistant Klebsiella spp., especially those in neonatal wards, are often caused by new types of strains, the so-called extended-spectrum-beta-lactamase (ESBL) producers. The incidence of ESBL-producing strains among clinical Klebsiella isolates has been steadily increasing over the past years. The resulting limitations on the therapeutic options demand new measures for the management of Klebsiella hospital infections. While the different typing methods are useful epidemiological tools for infection control, recent findings about Klebsiella virulence factors have provided new insights into the pathogenic strategies of these bacteria. Klebsiella pathogenicity factors such as capsules or lipopolysaccharides are presently considered to be promising candidates for vaccination efforts that may serve as immunological infection control measures.

Cross Infection↗

PubMed2003

Prognostic value of normal exercise and adenosine (99m)Tc-tetrofosmin SPECT imaging: results from the multicenter registry of 4,728 patients.

UNLABELLED: Event rates associated with a normal or low-risk myocardial perfusion SPECT imaging study have been shown by numerous investigators to be associated with <1%/y of follow-up. Thus, the aim of this study was to evaluate the prognostic value of a normal (99m)Tc-tetrofosmin study in a geographically diverse registry of patients undergoing stress myocardial perfusion SPECT. A total of 4,728 consecutively tested patients who underwent stress (99m)Tc-tetrofosmin SPECT at 5 U.S. hospitals were included in this series. METHODS: Patients were monitored for the occurrence of major cardiac events and hospitalizations. Uniform methods of data collection and standardized epidemiologic methods for follow-up were used at all centers. We used a risk-adjusted, Cox proportional hazards model to assess time to cardiac death. RESULTS: Of the 4,728 patients, one third underwent adenosine stress SPECT and two thirds underwent treadmill exercise. The observed annualized survival rate for those patients with a normal (99m)Tc-tetrofosmin study was 0.6%. Similarly, excellent survival rates were noted for the male and female subsets of this population as well as for patients who could exercise and for those undergoing pharmacologic stress testing. Compared with prior published outcomes studies on stress (201)Tl or (99m)Tc-sestamibi SPECT, the overall survival rates were similar and ranged from 99.3% to 99.7%. CONCLUSION: Results from this large multicenter registry provide further supportive evidence that the excellent prognosis associated with a normal SPECT scan is independent of the radiopharmaceutical used.

Adenosine↗

PubMed1997

De novo cancers complicating renal transplantation: experience in the Nordic countries.

OBJECTIVES: This report summarizes the experience in the Nordic countries with de novo cancer complicating renal transplantation and the prospects of a new Nordic EU-SPONSORED study (EURO-CAT) covering all kinds of organ transplantations. METHODS: Epidemiological studies are performed using standard methods of cohort analysis. The expected numbers of cancer cases in each stratum are calculated by applying the stratum- and site-specific cancer incidence rate of the national population to the appropriate number of person-years at risk. The observed/expected ratio is taken as the relative risk (standardized incidence ratio, SIR). Differences in SIRs between subcohorts are tested by evaluating the rate ratio. Laboratory methods include immunopathological, virus serological cytokine and tissue type analyses. Treatment includes discontinuation of immunosuppression and long-term high dose aciclovir. RESULTS: In our most recent analyses an incidence 3-5 times higher than that of the general population has been found, including most types of tumors, however with an uneven pattern with emphasis on lip-cervical-, vulvar-, urological-, skin cancers and lymphoprolipherative disorders (PTLD). Most tumors occur early (incl. PTLD) after transplantation, tumors of the skin however later and with an increase with time. In our present analysis we follow all types of organ transplantation, up to the most recent date, to consider the many new immunosuppressive agents for their risk of inducing cancer. Laboratory analyses have pointed to IL-10 as a possible cofactor in the development of EBV-induced PTLD. Treatment with aciclovir and discontinuation of immunosuppression may in some cases lead to recovery from the malignancy, sometimes even without harming the graft function.

Age Factors↗

PubMed1991

[The Paquid research program on the epidemiology of dementia. Methods and initial results].

Paquid is an epidemiological study designed to gather and follow up a cohort of 4,000 elderly subjects (65 years and older) living at home in order to study normal and pathological brain aging. These subjects were randomly chosen in the general population of 75 communities of South-Western France. We present the results of the data collected from 2,792 subjects on the prevalence and the correlates of clinically diagnosed dementia. The DSM III criteria for dementia were met by 101 subjects (3.62 p. 100). These cases were reviewed by a neurologist to confirm the diagnosis and to determine the cause of dementia using the NINCDS-ADRDA criteria. Forty-three subjects were classified as probable Alzheimer's disease; 8 as possible Alzheimer's disease; 5 as vascular dementia; 5 as Parkinson's disease with dementia; 2 as alcoholic dementia; 2 as "dementified psychosis"; and 1 unclassified. Fifteen patients refused to be examined by the neurologist, 18 were false-positives, and 2 died before the neurologists visit. Using the NINCDS-ADRDA criteria, the prevalence of dementia was as low as 1.6 p. 100. The prevalence of probable Alzheimer's disease decreased dramatically as educational level increased, lung 5.4 p. 100 for subjects with no education, 1.7 p. 100 for subjects with grade school level, 0.4 p. 100 for subjects with high school level and 0.4 p. 100 for subjects with university degrees. The relationship between dementia and educational level is still controversial in the literature. In this study the sample was large and randomly selected; all the demented cases fulfilled the NINCDS-ADRDA criteria. This suggests that educational level is indeed an important correlate of dementia in the French elderly community.

Aged↗

PubMedDate not supplied

Community diagnosis: its uses in the training of community health workers and in primary health care in East Africa.

Over the last 20 years, medical schools in Uganda, Kenya and Tanzania have been developing teaching programs in community health which have placed increasing emphasis on community diagnosis. This process, which involves students, health workers and the community, is a team effort to obtain a wide variety of information using epidemiologic methods and to establish priorities for health action. The programs which are developed following community diagnosis often rely on primary health workers and small health centers for their execution. Experience in community diagnosis is an important element in the training of health workers. Such experience is also an excellent means of teaching the management skills that are essential for operating primary health care programs. This paper traces the evolution of the methods of community diagnosis used in East Africa.

Africa, Eastern↗

PubMed1993

The epidemiology of contact lens related diseases in the United Kingdom.

This review evaluates the epidemiologic methods used to study contact lens related diseases in the United Kingdom. The results of these studies are compared to major US studies. The advantages and limitations of various epidemiologic study designs are discussed. The role of noncomparative cohort studies, particularly premarket studies, in underestimating lens related disease is examined. Descriptive studies and the difficulties related to their interpretation are also described. The use of case control studies for investigating both the risks and causes of lens related diseases is evaluated and compared to the cohort study design. The results of these studies in the investigation of the complications of contact lens wear, including keratitis, are summarized. Finally, the relevance of these findings to contact lens wearers and practitioners is explored.

Acanthamoeba Keratitis↗

PubMed1985

Diet and cancer: value of different types of epidemiological studies.

Diet and nutrition are increasingly recognized as likely to be major determinants of cancer, notably cancers of the gastrointestinal tract, breast, endometrium, ovary, and prostate. Dietary factors may collectively account for a greater proportion of all cancers that occur in contemporary Western society than does any other category of environmental exposure (1). With the development of knowledge of the protective properties of certain components of food, links with diet have been suggested for other cancer sites (2). The epidemiological evidence for the association of diet and cancer is, however, not uniformly convincing; also, the likely biological pathways are not always clear. In this paper, we comment on some current hypotheses in this area and examine the best epidemiological methods to test them.

Diagnosis-Related Groups↗

PubMed1983

Standardization of methods in the epidemiology of diabetes mellitus.

While considerable advances have been made in devising standardized methods for epidemiologic studies, it is only recently the standardized methods for use in diabetes epidemiology have been seriously considered. It is hoped that the present paper will provoke further attention to these matters and result in further discussions of areas where it appears possible to reach a consensus. Research into the performance of certain of the methods mentioned is urgently needed, and it is hoped that epidemiologists interested in diabetes will take up this challenge to prove or disapprove that some of the recommendations and suggestions made in this paper are useful and worthwhile.

Diabetes Mellitus↗

PubMed1978

A model for epidemiologic research.

Health sciences students should understand the fundamentals of epidemiologic methods that can lead to major advances in the treatment of disease. To this end, the research process is defined and a three-dimensional model that considers some basic elements of epidemiologic research--time, place, and strategy--is described. The strategies available to the investigator (descriptive, analytic, and experimental) and the possible time frames (retrospective, concurrent, and prospective) are illustrated in terms of field investigations that involve problems of infection, nutrition, dysplasia, metabolism, and cancer. It is believed that epidemiologic studies, no matter where they are performed, have certain features in common, especially those related to the elements of strategy and time.

Epidemiologic Methods↗

PubMed2001

[Community-acquired legionellosis in the Barcelona region between 1992 and 1999: epidemiological characteristics and diagnostic methods].

BACKGROUND: The epidemiological characteristics of community-acquired legionellosis are not well known. We present here legionellosis cases appearing in Barcelona, Spain, districts during 1992-1999. PATIENTS AND METHOD: Questionnaire on socio-demographic, epidemiological, clinical and diagnostic data. 285 community-acquired cases of legionellosis were notified (67% of total). Incidence values increased from 0.03/100,000 in 1992 to 3.14 in 1999. Mostly used diagnostic method since 1996 was the urinary antigen test. CONCLUSIONS: The incidence of legionellosis increased sharply during the studied period. We believe that use of urinary antigen-based diagnosis allows for a better knowledge of community-acquired legionellosis.

Community-Acquired Infections↗

PubMed2001

A primer in epidemiologic methodology.

Epidemiology is defined as the study of the distribution and determinants of disease within populations. In addition to the requirements for disease surveillance, epidemiologic methods have numerous applications in laboratory animal science and can reveal important insights into the multifactoral mechanisms of disease, thereby aiding in the design of optimized intervention strategies. Observational approaches to data collection can be used to quantify the role of causal factors under natural circumstances, complementing the value of experimental studies in this field. The meaning and appropriate use of standard measures of disease frequency and exposure-disease relationships are reviewed, along with explanations of bias and confounding. Recommendations for reporting the methods and findings from this type of work in comparative medicine literature are presented. Aspects of model-based approaches to data analysis are introduced, offering further opportunities for gaining needed information from epidemiologic study of problems in laboratory animal medicine and management.

Animal Diseases↗

PubMed1993

An epidemiological approach to quality assurance in the hospital.

This article discusses epidemiological methodology: comparing rates, confounding, the use of confidence intervals, Bayes' theorem, and occurrence screening. An appreciation of the limits of epidemiological methods will provide the manager with realistic expectations of the quality assurance process.

Bayes Theorem↗