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PubMed1996

Epidemiology and health policy--a world of difference? A case-study of a cholera outbreak in Kaputa district, Zambia.

The relationship between epidemiology and health policy is an area of considerable debate. This article demonstrates the use of epidemiological methods to make health policy formulation more 'policy significant' and 'down to earth'. A case-study of a cholera outbreak in Kaputa district, Zambia is used as an illustration. A closer liaison between epidemiology and social sciences is advocated. Epidemiological data should be supplied as feed back to the study population to facilitate community-based action for health.

Cholera↗

PubMed2004

Controlling emerging diseases in the 21st century.

The presentation addressed the following points: the role of veterinary epidemiology in emerging and global disease outbreaks; the contribution of veterinary epidemiology discipline to understanding and prevention of infections and other emerging animal disease, and the challenges for the discipline of veterinary epidemiology in the near future. The emerging and re-emerging infections animal diseases have contributed to expand the outlook of veterinary epidemiology. Methods and approaches in this discipline have been modified to satisfy the needs of society and of the scientific community. Mistakes and "bad turns" were made and should be avoided in the future. Veterinary epidemiology is alive and growing.

Animals↗

PubMed1994

[Role of population-based cancer registry in cancer epidemiology--epidemiological studies in the Cancer Registration Scheme in Osaka, Japan].

A population-based cancer registration scheme started in three areas in Japan in the 1950s solely for studying cancer incidence in their respective areas. Soon thereafter, several prefectural governments started their own schemes as part of their cancer control programs, effectively expanding the aims of cancer registration: to clarify cancer facts, to elevate the medical care for cancer patients, and to plan and evaluate cancer control programs. The Osaka Cancer Registry (OCR) started in 1962, and has been using epidemiological methods as a tool in constructing its registration scheme, as well as analyzing and utilizing registry data. This report deals with the results obtained in the OCR, classifying these results into four activities of epidemiology. 1. Clarifying cancer facts (descriptive epidemiology): The OCR has been observing incidence, medical care for cancer patients, distribution of cases by clinical stage, and the 5-year relative survival rate, and has estimated the prevalence rate, cured-case rate, and future incidence into the 21st century. Population-based data on histology and multiple cancers collected at the OCR have also contributed to the new approaches in cancer epidemiology. 2. Research on risk factors (analytical epidemiology): The OCR developed a computerized record-linkage system in 1970. This not only made registry work more effective and reliable, but many cohort studies were able to be conducted with relatively little effort and highly reliable results. The cancer case file in the OCR has been linked with the newly prepared data file of the study group, and cancer incidence among the study group has been observed. Finally, cancer risks of possible causal factors in that group have been estimated quantitatively. 3. Evaluation of control programs: Secondary prevention programs (early detection) have been conducted in Japan as major cancer control programs, because effective risk factors were not previously defined. OCR data have been used for estimating sensitivity and specificity of screening tests for various cancers, as well as for evaluating the effect of clinical work on improving survival and on decreasing cancer deaths. 4. Planning future cancer control programs: The OCR has reported on the probable rapid increase of cancer incidence in the 21st century, especially of elderly cancer cases, and cancer cases with poor survival. To control these difficult problems, new cancer programs should be urgently designed and implemented. The authors have recommended that programs be prepared by cancer site, and have already presented a detailed program for lung cancer control.

Cohort Studies↗

PubMed1984

Epidemiological and clinical research as a guide in the search for risk factors and biological markers.

One of the major events in psychiatric research in the last decade has been the firm establishment of the concept of biological markers and risk factors as legitimate signposts in the search for causes and pathogenetic mechanisms in mental disorders. However, to date, no single variable and no group of variables have been unequivocally identified as markers or risk factors, as far as the functional psychoses, or personality and neurotic disorders are concerned. The reasons for this state of affairs lie in the multifactorial nature of "idiopathic" psychiatric disorders, in persisting differences between the diagnostic criteria employed by various "schools", in the low statistical power of most research designs in biological psychiatry and in the lack of a general theory of cerebral and mental functioning which can yield testable hypotheses. Epidemiological methods, which had produced spectacular results in the past, are now rarely applied to narrow down the field of investigation where disease markers are most likely to be found. There are obvious similarities between the epidemiological strategy of risk factor identification and the biological strategy of disease marker research. A combination of these two strategies is more likely to advance the field than continued use of each singly. Schizophrenia research is an example of an area presenting interesting opportunities in this respect. The following priorities are suggested: development of a research classification of schizophrenia proceeding from well-defined sub-divisions of the phenotype; studies of the schizophrenia spectrum of disorders; search for populations with extremely high or extremely low incidence; studies of large pedigrees; further attempts to clarify the phenomenon of seasonal distribution of births of schizophrenia patients; studies on the occurrence of schizophrenic syndromes in association with other, well-defined diseases; search for early developmental precursors of the disorder; and subtyping of schizophrenia according to therapeutic response.

Epidemiologic Methods↗

PubMed1997

Prevalence of Sjögren's syndrome in a closed rural community.

OBJECTIVE: To define the prevalence of Sjögren's syndrome (SS) through an epidemiological survey in a closed rural community. The classification of SS is based on the validated criteria reported by a multicentre study performed in Europe and supported by the Epidemiology Committee of the European Community (EEC-COMAC Epidemiology). METHODS: The population under study consisted of 837 women aged 18 years or older, residing in the Astakos community of Aitoloakarnania, Greece. The study protocol was subdivided in two parts. In part I, an exhaustive epidemiological survey of these women was conducted in July and August of 1992. The validated questionnaire used in the survey assesses both ocular and oral involvement. In part II, 45 of the women reporting symptoms of both dry eye and dry mouth were approached for a full examination based on the validated set of classification criteria of SS. The full complement of the diagnostic tests was performed on 35 of these women. A subject is classified as a definite primary SS case if at least four of six items of the subject's test items are positive. If three of six items are positive the subject is classified as a probable primary SS case. RESULTS: The classification criteria for definite primary SS were satisfied by five women. This number corresponds to an estimated prevalence of 0.60% (exact 95% CI 0.19%, 1.39%). Probable primary SS was diagnosed for 25 women (prevalence = 2.99%). CONCLUSION: Because of the loss of follow up (10 of 45) and the use of slightly stricter criteria for inclusion of possible SS cases in part II of the study, we consider our estimate of the prevalence of SS to be conservative. This study concurring with other recent reports, suggests that SS is more prevalent than previously thought.

Adolescent↗

PubMed1990

[The pediatrician and epidemiology].

Pediatrics and epidemiology are two specialties of medicine with independent training. The pediatrician is trained in a clinical setting with practice and theoretical knowledge throughout several years in an accredited hospital, whereas the epidemiologist is trained in a more theoretical basis with field works as its practice. Nevertheless, the pediatrician constantly uses the epidemiological method although he or she may not be aware of this. The purpose of this paper is to explain in a very short way, the relationship between both disciplines. Aspects of descriptive, analytic and experimental epidemiology are given.

Case-Control Studies↗

PubMedDate not supplied

Gene-environment interaction: definitions and study designs.

Study of gene-environment interaction is important for improving accuracy and precision in the assessment of both genetic and environmental influences. This overview presents a simple definition of gene-environment interaction and suggests study designs for detecting it. Gene-environment interaction is defined as "a different effect of an environmental exposure on disease risk in persons with different genotypes," or, alternatively, "a different effect of a genotype on disease risk in persons with different environmental exposures." Under this strictly statistical definition, the presence or absence of interaction depends upon the scale of measurement (additive or multiplicative). The decision of which scale is appropriate will be governed by many factors, including the main objective of an investigation (discovery of etiology, public health prediction, etc.) and the hypothesized pathophysiologic model. Five biologically plausible models are described for the relations between genotypes and environmental exposures, in terms of their effects on disease risk. Each of these models leads to a different set of predictions about disease risk in individuals classified by presence or absence of a high-risk genotype and environmental exposure. Classification according to the exposure is relatively easy, using conventional epidemiologic methods. Classification according to the high-risk genotype is more difficult, but several alternative strategies are suggested.

Causality↗

PubMed1990

Methodological issues in the epidemiological study of alcohol-drug problems: sources of confusion and misunderstanding.

Epidemiological research on psychoactive substance use disorders can and sometimes does lead to conclusions that are mutually conflicting. A current example is the apparent drop in substance use among adolescents in schools, with continuing high levels of substance-associated adolescent suicide, hospitalization, and crime. In an effort to clarify such differences, the author underscores the importance of understanding the three most common epidemiological methods. Each has different histories, advantages, liabilities, inherent value sets, and disparate-but-overlapping purposes.

Adolescent↗

PubMed1994

Health management in herds.

In this paper, the general process of health management and disease prevention at the herd level is described. The important steps include data collection, calculation of performance parameters, decision making, data analysis, problem definition, and finally installing preventive and therapeutic measures. Important components of a successful health management program include reliable data collection, automated data analysis, excellent veterinary clinical skills, and knowledge of epidemiological methods.

Animal Husbandry↗

PubMed1999

[The decision to treat based on epidemiological methodology: the paradigm of hypercholesterolemia].

The author reviews the epidemiological methods, both non experimental and experimental, founding evidence-based medicine. As an example, he reviews the evolution of the scientific knowledge about the relationship between hypercholesterolemia and coronary heart disease and about the determinants of the serum cholesterol concentration. Epidemiology studies the causal chain between exposure and event (sickness) and proposes, within the framework of primary and secondary prevention of coronary heart disease, interventions to interrupt the causal chain at a given level.

Causality↗

PubMedDate not supplied

Study designs appropriate for the workplace.

Carlo and Hearn have called for "refinement of old [epidemiologic] methods and an ongoing evaluation of where methods fit in the overall scheme as we address the multiple complexities of reproductive hazard assessment." This review is an attempt to bring together the current state-of-the-art methods for problem definition and hypothesis testing available to the occupational epidemiologist. For problem definition, meta analysis can be utilized to narrow the field of potential causal hypotheses. Passive active surveillance may further refine issues for analytic research. Within analytic epidemiology, several methods may be appropriate for the workplace setting. Those discussed here may be used to estimate the risk ratio in either a fixed or dynamic population.

Actuarial Analysis↗

PubMed2000

Causation: the elusive grail of epidemiology.

The paper discusses the evolving concept of causation in epidemiology and its potential interaction with logic and scientific philosophy. Causes are contingent but the necessity which binds them to their effects relies on contrary-to-fact conditionals, i.e. conditional statements whose antecedent is false. Chance instead of determinism plays a growing role in science and, although rarely acknowledged yet, in epidemiology: causes are multiple and chancy; a prior event causes a subsequent event if the probability distribution of the subsequent event changes conditionally upon the probability of the prior event. There are no known sufficient causes in epidemiology. We merely observe tendencies toward sufficiency or tendencies toward necessity: cohort studies evaluate the first tendencies, and case-control studies the latter. In applied sciences, such as medicine and epidemiology, causes are intrinsically connected with goals and effective strategies: they are recipe which have a potential harmful or successful use; they are contrastive since they make a difference between circumstances in which they are present and those in which they are absent: causes do not explain event E but event E rather than even F. Causation is intrinsically linked with the notion of "what is pathological". Any definition of causation will inevitably collapse into the use made of epidemiologic methods. The progressive methodological sophistication of the last forty years is in perfect alignment with a gradual implicit overhaul of our concept of causation.

Causality↗

PubMed2005

Epidemiological causality.

Epidemiological methods, which combine population thinking and group comparisons, can primarily identify causes of disease in populations. There is therefore a tension between our intuitive notion of a cause, which we want to be deterministic and invariant at the individual level, and the epidemiological notion of causes, which are invariant only at the population level. Epidemiologists have given heretofore a pragmatic solution to this tension. Causal inference in epidemiology consists in checking the logical coherence of a causality statement and determining whether what has been found grossly contradicts what we think we already know: how strong is the association? Is there a dose-response relationship? Does the cause precede the effect? Is the effect biologically plausible? Etc. This approach to causal inference can be traced back to the English philosophers David Hume and John Stuart Mill. On the other hand, the mode of establishing causality, devised by Jakob Henle and Robert Koch, which has been fruitful in bacteriology, requires that in every instance the effect invariably follows the cause (e.g., inoculation of Koch bacillus and tuberculosis). This is incompatible with epidemiological causality which has to deal with probabilistic effects (e.g., smoking and lung cancer), and is therefore invariant only for the population.

Biology↗

PubMed1984

Problems of ascertainment of congenital anomalies.

Problems of ascertainment bedevil the investigation of the etiology of congenital anomalies in singletons and in multiple births by epidemiological methods. It is shown that the definition of the population of affected births is ambiguous and that the problem of tracing etiology is complicated by the systematic way in which anomalies may be missed at birth. The available methods of dealing with problems of ascertainment are reviewed. Methods of adjusting for possible bias of ascertainment of affected births, by fitting statistical models to data from several sources, have been employed in some previous studies. In these methods, it is assumed that there are no errors of diagnosis or of recording. However, it is shown that there may be discrepancies in recorded diagnoses between sources, rendering this assumption untenable. In these methods, it is also assumed that the model which is the best fit to the data on the ascertained cases in also the best model for the cases which were not ascertained. This assumption is tested indirectly in a retrospective analysis of data from Aberdeen and Belfast collected concurrently through routine recording systems. It is demonstrated that there was a social process in ascertainment which renders the methods of adjusting for bias of ascertainment at best very complicated and at worst inapplicable.

Congenital Abnormalities↗

PubMed2000

The effects of competency requirements in Part II MFPHM submission--a study of the abstracts of successful reports.

BACKGROUND: The objectives of this study are to explore the effects of the new 1996 guidance requiring explicit demonstration of competencies on the nature of successful MFPHM Part II reports, how successful candidates claimed competency areas in their two reports and the effects of the subject areas of the report on the specific competencies claimed. METHODS: The abstracts of candidates who passed the examination from January 1996 to January 1999 were studied. Information was extracted on candidate's region, year of the abstract, examination guidance, subject area, methods and data used, format of the abstract, and level (e.g. national, regional, etc.) for which the work was performed. RESULTS: Compared with reports submitted under the 1992 guidance, those submitted under the 1996 guidance were more likely to have a structured abstract, and to employ descriptive epidemiological methods and routine data, and were less likely to be case-control or retrospective studies. There were no other significant differences in the level for which the work was performed, the subject area, or the methods and data used. Thirty-nine per cent of candidates under the 1996 guidance claimed at least one identical competency area in both reports, most frequently for health needs assessment and literature review. Each of the four competencies was demonstrated by a significant proportion of reports in each subject areas. CONCLUSIONS: The new examination guidance had only minor effects on the nature of successful Part II reports. Candidates used different strategies for claiming competencies, apparently at the choice of individual trainees and trainers. The competency requirements did not appear to limit the range of work performed.

Abstracting and Indexing↗

PubMed1996

Combined analysis of matched and unmatched case-control studies: comparison of risk estimates from different studies.

The authors propose a method to perform a combined analysis of matched and unmatched case-control studies that is based on an adaptation of logistic regression and can be performed using standard software. This methodology can be used to do pooled analyses of studies with different designs. Likelihood ratio tests can be performed to assess association, heterogeneity, or trend. The standard errors of the coefficients allow the derivation of a Wald test and the calculation of confidence intervals. Another application is to compare relative risk estimators for the same risk factors studied in different phases of a disease in an effort to explore factors that may be more important in one phase than in another. Interaction terms of risk factors with variables that code the different pooled studies can be used for this purpose. The advantage of using this method is that a formal statistical comparison can be performed in which the regression coefficients of the interaction terms estimate the relative differences in risk (odds ratio ratios) between the studies. This estimation can be adjusted for other confounder factors. Two examples of application using data from case-control studies on cervical cancer and colorectal cancer are presented to illustrate the use of this epidemiologic method.

Case-Control Studies↗

PubMed1986

Early oral contraceptive use and breast cancer: theoretical effects of latency.

Many cancers and other chronic diseases are associated with a long delay between exposure to a putative risk factor and subsequent diagnosis. This presents well recognised problems in the elucidation of suspected risk factors by epidemiological methods. In this paper we discuss the interpretation in epidemiological studies of the effect of a possible risk factor when population exposure is recent and rapidly changing. An important contemporary example concerns the study of early oral contraceptive (OC) use in relation to the subsequent risk of breast cancer. Computer simulations reported here indicate that plausible delays in the manifestation of any effect on breast cancer incidence make it difficult to exclude early OC use as a risk factor for breast cancer, even when large well conducted epidemiological studies show no apparent increased risk. Methods for detecting a 'latent' effect are discussed.

Breast Neoplasms↗

PubMed1979

The need for epidemiological research in road trauma.

This paper discusses the application of epidemiological methods to the public health problem of road trauma. The complex nature of the system is stressed, and some consequent difficulties in the formulation of appropriate hypotheses are outlined. Examples are given. To solve these problems, the paper proposes the formation of multidisciplinary full-time epidemiological research teams.

Accidents, Traffic↗