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PubMedDate not supplied

[Organization of sanitary and epidemiological measures to protect the Omsk region involved in epizootia of avian flu].

In article organizational aspects of carrying out preventive and antiepidemic actions at a regional level are considered at the bird's flu epizootia. Epizootic researches have shown, that infection of poultry has taken place as a result of contact to a wild bird. Serological inspection 521 persons on presence of antibodies to a influenza A (H5N1) has not revealed seropositive persons. The conclusion, that the forecast of development of a situation for spring of 2006 is made in view of a direction of migration of a wild waterfowl is unfavourable.

Animal Migration↗
PubMed1995

[Organization of epidemiological measures in surroundings of patients with active pulmonary tuberculosis with undetermined bacterial discharge].

It is stated that family members and neighbours of patients with active tuberculosis of the lungs with indefinite bacterial discharge are at higher risk to develop tuberculosis than other population. In such foci of tuberculosis prompt antituberculosis measures are recommended even though final results on bacterial discharge of the patient are not yet available.

Adult↗
PubMed1994

[Errors of measurement and epidemiology].

The quantification of measurement errors is rarely considered during the preparation of a study protocol in epidemiology. This is in contradiction with the impact of these errors on the assessment of degree of association between various measures, which is often the objective of these protocols. A few important definitions of measurement errors are first proposed. The impact of these errors on the assessment of measures of central tendency and association is studied through examples and simple simulations. These measures must be exact since they play such an important role in estimating risk factors or in evaluating diagnostic tests.

Analysis of Variance↗
PubMed2002

Case studies in the use of toxicological measures in epidemiological studies.

One of the major limitations in environmental epidemiological studies investigating associations between chemical exposures and the risk of disease is the use of crude exposure metrics. This increases the risk of exposure misclassification, reducing the chance of finding a real association, where one exists. In environmental epidemiological studies, surrogate exposure measures, such as time living in a contaminated area, do not adequately reflect the true nature and/or degree of real exposure to the chemical substance(s) of interest. Also, as they are not quantitative measures of absorbed dose, the data provided by such measures cannot give numerical measures of a dose response relationship, limiting their use in quantitative risk assessment. In epidemiological studies, biological measures of exposure should be used, if available, as they are close to the target organ dose and provide greater precision in risk estimates and dose response relationships. Examples are the measurement of speciated arsenic in the urine of subjects when investigating health effects from arsenic exposure, and the use of breast milk lipid concentration to measure body burden when conducting epidemiological studies of health effects from persistent lipophilic compounds, such as the endocrine disruptors. This paper discusses the main uses of such exposure measures, using several case studies, their limitations and some challenges in the future for toxicologists to develop more suitable measures for epidemiologists to use in population studies.

Animals↗
PubMed2004

Measurement in epidemiology.

Data (information) are the building blocks of epidemiological research. Careful measurement, recording and handling of information are crucial to the research process. The nature of the data required must be precisely defined and its collection requires the use of reliable tools or instruments. Standardisation of definitions and procedures used in measurement helps to ensure comparability. Care in undertaking measurements and rigorous training of personnel carrying out the measurements help to ensure precision. Special care is necessary to ensure completeness and accuracy in recording the data. Information may be obtained from routine or especially designed forms and evaluated by counting deaths or cases of disease or measures of dysfunction. Questionnaires are a frequently used instrument for collecting information. They should include data identifying the individual being studied, followed by specific questions concerning diseases and determinants. To be useful, such questionnaires must be carefully structured. Diseases are usually compared by calculating 'rates' or 'risks', consisting of numerators (cases, events) and denominators (population). Prevalence and incidence are standard measures of 'risk'. The collection of high quality information (data) and its use to construct estimates of 'risk' or risk ratios form the basis of epidemiology.

Data Collection↗
PubMed2000

Choice of effect measure for epidemiological data.

The debate concerning the choice of effect measure for epidemiologic data has been renewed in the literature, and it suggests some continuing disagreement between the pertinent clinical and statistical criteria. In this article, some defining characteristics of the main choices of effect measure [risk difference (RD), relative risk (RR), and odds ratio (OR)] for binary data are presented and compared, with consideration of both the clinical and statistical perspectives. Relationships of these measures to the relative risk reduction (RRR) and number needed to treat (NNT) are also discussed. A numerical comparison of models of constant RD, RR, and OR is made to assess when and by how much they might differ in practice. Typically the models show only small numerical differences, unless extreme extrapolation is involved. The RD and RR models can predict impossible event rates, either less than zero or greater than 100%. Each measure has potential theoretical justification. RD and RR may enjoy some advantages for communication of risk, but OR may be preferred for data analysis. A clear distinction should be maintained between the objectives of data analysis and subsequent risk communication, and different effect measures may be needed for each.

Humans↗
PubMed1992

Comparison of bronchial reactivity and peak expiratory flow variability measurements for epidemiologic studies.

Inclusion of a standardized measurement of airway function is important in epidemiologic studies of asthma to facilitate comparison between different studies. Bronchial reactivity is widely used in such studies, but measurement of peak expiratory flow (PEF) variability has a number of potential advantages. We compared PEF variability with methacholine challenge tests in a community population sample. Subjects selected at random (n = 95) and on the basis of having experienced wheeze in the last 12 months (n = 130) performed a challenge test with methacholine to a maximum dose of 12.25 mumol and made serial PEF recordings every 2 h for a week. PEF variability was expressed as mean daily maximum amplitude as a percentage of the mean (amplitude % mean). Increased bronchial reactivity and PEF variability were arbitrarily defined as values above the 10th or below the 90th percentiles in the random sample. A measurement of amplitude % mean was available from all 225 subjects, whereas only 115 (51%) had a measurable PD20 methacholine. PD20 measurements correlated weakly but significantly with amplitude % mean (r = -0.44, p less than 0.001). Increased values of both bronchial reactivity and PEF variability were related to the presence of respiratory symptoms in the week before testing. Asthma was more strongly related to increased bronchial reactivity than to PEF variability. Both measurements showed a strong association with atopy and the intraclass correlation coefficients (ratio of between-subject to total variance) were similar for both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

Blood pressure measurement in epidemiological studies: a comparative analysis of two methods. Data from the EPIC-Potsdam Study. European Prospective Investigation into Cancer and Nutrition.

OBJECTIVE: To investigate the impact of a device replacement in blood pressure measurement in epidemiological studies on comparison and interpretation of epidemiological data by replacing traditional aneroid manometry with automated oscillometric devices. DESIGN: Within the context of a continuing epidemiological study (EPIC-Potsdam Study), blood pressure measurements were performed simultaneously with an aneroid sphygmomanometer and an automated oscillometric device for each subject. We randomly selected 400 men and women from the main study population and one observer performed three consecutive blood pressure measurements for each subject according to a standardized procedure. In total, 10 oscillometric devices of the same type were used. Demographic and anthropometric data for each subject were obtained by trained interviewers. RESULTS: The mean difference between the aneroid and the oscillometric measurements of systolic blood pressure was 0.2 +/- 5.6 mmHg (aneroid value greater, NS), whereas the mean difference in diastolic blood pressure, 0.5 +/- 3.5 mmHg (aneroid value smaller), attained statistical significance (P = 0.0001). Estimates of prevalence for hypertension differed by 0.4% for women, and by 2.9% for men. Associations with the differences between methods were observed with age, blood pressure, lean body mass, upper arm circumference and specific devices without indicating a strong and consistent pattern. CONCLUSIONS: The use of automated oscillometric devices in epidemiological studies introduces a bias of very small magnitude compared with use of the aneroid method. The effect of the change to this automated measurement procedure on prevalence estimates is small but might affect comparability of data. Minor differences in measurement performance between devices of one type might affect population parameters.

Adult↗
PubMed2003

[Study on the epidemiology and measures for control on severe acute respiratory syndrome in Guangzhou city].

OBJECTIVE: To analyze the epidemiological characteristics, related risk factors, measures for its control of severe acute respiratory syndrome (SARS). METHODS: Data on epidemiological features, pathogens and measures for control were collected and analyzed. RESULTS: Since Jan 2003, infectious atypical pneumonia (AP) has become epidemic in Guangzhou city. The first autochthonous case was identified on Jan 2nd. Number of cases started to increase since February and reached peak in the early 10 days of February. Hereafter the epidemic tended to decline in March and since early April, the average number of new cases began to decrease, less than 10 per day. Epidemiological studies revealed that the number of cases aged between 20 and 50 was higher than that below the age of 20. Of the total 966 cases, 429 were males versus 537 females. Geographically, the epidemics covered all 13 districts of Guangzhou, but 95% of the cases concentrated in 7 urban districts. As for professional distribution, health care workers accounted for 28.67% of the total cases. There were 36 deaths, aged from 5 to 89, with half of them older than 60. Out of the victims, 38.9% of them had complications as hypertension, diabetes, heart diseases and COPD etc. Data regarding the clustering features of cases showed that there were 42 families having 2 or more cases in one family, while 277 health workers suffered from SARS were concentrated in 28 hospitals. Only one outbreak took place in a public setting but no outbreak was reported in schools. Relevant research also indicated that SARS could be classified as an air-borne infectious disease, transmitted through aerosol and droplets, but close contact also played an important role in the mode of transmission. The disease was highly infectious, suggesting that people who had close contact with patients in the place with poor ventilation was in greater risk of getting infection. The incubation period ranged from 1 to 11 days (mainly from 3 to 8 days), with an average of 5 days. According to our observation, the following measures might be effective such as: early diagnosis, isolation and treatment provided to the patients, and suspected cases under medical observation should also be put in separate places. Improving ventilation and regular disinfection over air and stuff in hospital wards were also recommended. In order to prevent iatrogenic infection, sense on self-protection among health care workers must be strengthened. Patients were not allowed to be visited by any one other than hospital staff. CONCLUSION: SARS is a preventable disease and can be under control. It is of great importance to prevent clustered SARS cases and the prevention of iatrogenic infection is essential.

Adolescent↗
PubMed1990

Quality assessment of blood pressure measurements in epidemiological surveys. The impact of last digit preference and the proportions of identical duplicate measurements. WHO Monica Project [corrected].

In the WHO MONICA Project, cardiovascular risk factor surveys including measurements of arterial blood pressure (BP) were conducted in more than 50 different populations. In the course of a retrospective BP measurement quality assessment effort, two indicators of "prejudiced" blood pressure reading, last digit preference and high proportions of identical results in duplicate measurements, are used in addition to other items to evaluate blood pressure measurement quality. We used fictitious blood pressure distributions and applied to them Last Digit Preference scores and Proportions of Identical Duplicate Measurements actually found in the MONICA surveys. The analysis showed that Last Digit Preference affects predominantly the shape of the BP distribution curve, whereas high Proportions of Identical Duplicate Measurements may cause a shift of the entire BP distribution curve. Although the two items are partly interrelated, a clear distinction between them and their effects is advocated.

Adult↗
PubMed1988

The statistical analysis of multiple binary measurements.

Epidemiologic studies often compare several groups of subjects for the presence or absence of a specified biological trait, where each subject in a group contributes two or more observations to the analysis. Examples occur in ophthalmologic studies, where each subject contributes observations on each of two eyes, and dental studies, where observations on each of several teeth may be contributed. Application of the standard Pearson chi-square test to such data is not valid, since the resulting sample observations are not statistically independent. In this paper we show how simple adjustments can be made to the Pearson chi-square statistic that adjust for the within-subject clustering. Application to other types of investigations involving clustered data is also discussed.

Adult↗
PubMed2006

A brief conceptual tutorial of multilevel analysis in social epidemiology: using measures of clustering in multilevel logistic regression to investigate contextual phenomena.

STUDY OBJECTIVE: In social epidemiology, it is easy to compute and interpret measures of variation in multilevel linear regression, but technical difficulties exist in the case of logistic regression. The aim of this study was to present measures of variation appropriate for the logistic case in a didactic rather than a mathematical way. DESIGN AND PARTICIPANTS: Data were used from the health survey conducted in 2000 in the county of Scania, Sweden, that comprised 10 723 persons aged 18-80 years living in 60 areas. Conducting multilevel logistic regression different techniques were applied to investigate whether the individual propensity to consult private physicians was statistically dependent on the area of residence (that is, intraclass correlation (ICC), median odds ratio (MOR)), the 80% interval odds ratio (IOR-80), and the sorting out index). RESULTS: The MOR provided more interpretable information than the ICC on the relevance of the residential area for understanding the individual propensity of consulting private physicians. The MOR showed that the unexplained heterogeneity between areas was of greater relevance than the individual variables considered in the analysis (age, sex, and education) for understanding the individual propensity of visiting private physicians. Residing in a high education area increased the probability of visiting a private physician. However, the IOR showed that the unexplained variability between areas did not allow to clearly distinguishing low from high propensity areas with the area educational level. The sorting out index was equal to 82%. CONCLUSION: Measures of variation in logistic regression should be promoted in social epidemiological and public health research as efficient means of quantifying the importance of the context of residence for understanding disparities in health and health related behaviour.

Adolescent↗
PubMed1997

The use of biological markers as predictive early-outcome measures in epidemiological research.

One of the possible uses of biomarkers in epidemiological research is as early-outcome measures to predict the occurrence of clinical disease and to elucidate the biological mechanism of pathogenesis. This use is conceptually less straightforward than the well established use of biomarkers to improve or extend exposure assessment or to study interindividual variations in disease susceptibility. In principle, this form of use could accelerate or otherwise facilitate etiological research. However, in practice, the recent review literature suggests that this mode of biomarker use, especially in cancer epidemiology, is the least clear-cut and the least well developed. The recurrent problem is identifying biomarkers that: (1) are on the causal pathway, (2) have a high probability of progression to clinical disease, and (3) account for all or most of the cases of the specified clinical outcome. Such biomarkers would be most useful if they conferred a long lead-time relative to clinical disease occurrence.

Biomarkers, Tumor↗
PubMed1991

Reporting the accuracy of biochemical measurements for epidemiologic and nutrition studies.

Procedures for reporting and monitoring the accuracy of biochemical measurements are presented. They are proposed as standard reporting procedures for laboratory assays for epidemiologic and clinical-nutrition studies. The recommended procedures require identification and estimation of all major sources of variability and explanations of laboratory quality control procedures employed. Variance-components techniques are used to model the total variability and calculate a maximum percent error that provides an easily understandable measure of laboratory precision accounting for all sources of variability. This avoids ambiguities encountered when reporting an SD that may taken into account only a few of the potential sources of variability. Other proposed uses of the total-variability model include estimating precision of laboratory methods for various replication schemes and developing effective quality control-checking schemes. These procedures are demonstrated with an example of the analysis of alpha-tocopherol in human plasma by using high-performance liquid chromatography.

Analysis of Variance↗