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PubMed1983

Epidemiologic methodology as used in China.

Seven epidemiological methods commonly used in China are discussed. A communicable disease reporting system is in place but this does not include rheumatic diseases. Death registers include cause of death only in selected pilot study points. Field studies using either mobile clinics or nation-wide treatment and prevention programs are useful for infectious diseases. Disease specific surveys of mortality and prevalence are available for hypertension and tuberculosis. Some case control and efficacy studies are also undertaken. Thirty longterm disease surveillance points have been established throughout China.

China↗
PubMed1983

Primary health care provision in terms of community need in South Africa.

In South Africa, early lessons in primary health care were lost to sight and have been rediscovered only recently. Priorities need to be reassessed in order to better allocate resources to community needs. Developing and developed communities require different primary care services. Simple and effective epidemiological methods should be used to gather information required for planning and evaluation of services. In developing communities, where there is a shortage of doctors, trained nurses operate local clinics with the help of community workers. Community participation and the cooperation of the traditional healers are necessary. Appropriate training of personnel for an effective role in public health care is essential.

Community Health Services↗
PubMed1975

Some perspectives on the role of biostatistics and epidemiology in the prevention and control of mental disorders.

The paper reviews progress made in the past 30 years in the development of statistical and epidemiological methods in the mental health field. Applications have included determinations of need for psychiatric care and supporting personnel; interpretation of morbidity indices, and cross-national comparisons of diagnoses of mental disorders. Much remains to be done. Progress would include better measurement of incidence, duration, and prevalence of mental disorders; more precise estimates of service needs; more effective programs to prevent or reduce disability. Particularly needed are field-research units under long-term funding with the task of assessing effectiveness of mental health programs at the catchment-area level.

Classification↗
PubMed1979

Critical evaluation of the venereal disease control campaign in Poland 1970-76.

A comprehensive campaign to control venereal diseases was undertaken in Poland in 1970. During the eight-year period of the campaign a significant decrease in the morbidity rate of gonorrhoea and syphilis was achieved. The number of cases of primary and secondary syphilis decreased by 85% and the number of cases of gonorrhoea by 30%. This paper presents the main guidelines of the campaign and a critical evaluation of the various epidemiological methods applied, such as mass screening for syphilis and gonorrhoea, epidemiological treatment, contact-tracing, improvement of treatment methods, improvement of methods of health education, and training of physicians and laboratory staff in venereology.

Female↗
PubMedDate not supplied

Epidemiologic methodology in evaluating health technology.

Epidemiologic methods provide a basis for evaluating new medical technologies of varying complexity and sophistication. Use is made of the concepts of efficacy, effectiveness and efficiency, and cost-effectiveness. The available methods, observational and experimental, are reviewed in the context of evaluation of the intensive coronary care unit (ICCU). Most early studies that showed a benefit in low in-hospital case fatality rates for patients with myocardial infarction in the ICCU had serious flaws in design and analysis. Better studies failed to show any benefit, and some showed an increase in the case fatality rates in the ICCU when compared with the medical wards or even with patients treated at home (for noncomplicated infarctions). Most recent studies have attempted to predict which patients should and which should not be admitted to the ICCU, in order to improve efficiency.

Coronary Care Units↗
PubMed1997

The impact of host genetics on susceptibility to human infectious diseases.

The development of genetic epidemiology methods using recent human genetic mapping information, together with the growing availability of candidate genes, has led to major advances in the identification of host genes involved in human infectious diseases. Within the past year, highlights include the mapping of a locus controlling the intensity of infection by Schistosoma mansoni, the demonstration that mutations in the interferon-gamma receptor 1 gene are causative of disseminated infection due to weakly pathogenic mycobacteria, and the identification, in the CCR5 gene, of a deletion which provides high protection against HIV-1 infection. The impact of these findings on the understanding of infectious disease pathogenesis and on the design of future preventive and therapeutic strategies should be considerable.

Animals↗
PubMed1988

Study design for technology assessment: critical issues.

The epidemiological methods have become useful tools for the assessment of the effectiveness and safety of health care technologies. The experimental methods, namely the randomized controlled trials (RCT), give the best evidence of the effect of a technology. However, the ethical issues and the very nature of the intervention under study sometimes make it difficult to carry out an RCT. Therefore, quasi-experimental and non-experimental study designs are also applied. The critical issues concerning these designs are discussed. The results of evaluative studies are of importance for decision-makers in health policy. The measurements of the impact of a medical technology should go beyond a statement of its effectiveness, because the essential outcome of an intervention or programme is the health status and quality of life of the individuals and populations concerned.

Clinical Trials as Topic↗
PubMed2001

Evaluation of a two-test serodiagnostic method for community assessment of Lyme disease in an endemic area.

Epidemiological methods are needed to evaluate community exposure to Borrelia burgdorferi, the causative agent of Lyme disease (LD). For LD serodiagnosis, the Centers for Disease Control and Prevention (CDC) recommends a 2-test approach that involves enzyme immunoassay (EIA) testing and Western immunoblotting (WB) of EIA-equivocal and EIA-positive specimens. The specificity of this approach was evaluated among residents of a LD-endemic community and was compared with WB alone and with a simplified 2-test approach (WB of equivocal EIA only). Participants reporting no previous diagnosis of LD were recruited during a community-wide serosurvey on Block Island, Rhode Island. Of 80 eligible participants, 20 had received LD vaccine. Seven (35%) of 20 vaccinees and 22 (37%) of 60 nonvaccinees reported nonspecific symptoms compatible with LD in the previous year. In this highly LD-endemic community, the overall specificity of the CDC-recommended approach was highest (100%), followed by WB alone (98.7%), then the simplified approach (95%).

Blotting, Western↗
PubMed1976

Undetected opiate use in the Southwest: comparison of official drug-user files and treatment program patient records.

Highly disparate research techniques have been employed to develop estimates of the extent of opiate use. Exclusive reliance upon public health and law enforcement statistics has been supplemented in recent years with data generated by survey research "incidence and prevalence" epidemiological methods. State agencies attempting to measure the extent of opiate use as a requirement for the receipt of federal categorical grant formula funds utilize multiple indicators: opiate treatment, arrest, incarceration, serum hepatitis, narcotics overdose death, and survey data. To address the question of undetected opiate use in a major southwestern city, the authors have undertaken a study measuring the extent of law enforcement recognition of the addictive status of a random sample of patients selected from the city's two municipally operated methadone treatment programs. The results indicate that over one-half of the sample was unknown to the police as addicts. Descriptive attributes of the unknown group were identified through appropriate statistical analyses. These findings are comparable to those of a similar study conducted in 1973 in a major eastern city.

Adult↗
PubMed1989

How to study the aetiology of burn injury: the epidemiological approach.

Effective prevention of burn injury should be based on sound aetiological knowledge. This article deals with epidemiological methods to study the incidence of burn injury as a function of its risk factors. Central methodological issues are comparability of baseline prognosis, comparability of measurements (of effects in cohort studies and of risk factors in case-control studies), and comparability of external circumstances. These principles are clarified with a number of fictitious examples of risk factors for burn injury. It is explained that in preventive trials comparability may be achieved by randomization, blinding and placebo intervention. The main tools in non-experimental studies are deliberate selection and multivariate analysis. Special attention is given to the definition of the source population and to reducing measurement incomparability in case-control studies. Some well-designed case-control studies following these principles might bring effective prevention of burn injury some steps nearer.

Burns↗
PubMed1986

Analysis of the components of a linear trend in proportions.

The standard epidemiologic methods for evaluating trends in the prevalence or incidence of disease are reviewed, and a method is presented for assessing the contribution of a specific disease subgroup to the overall trend, based on the slope obtained by a grouped weighted linear regression of the proportions of persons experiencing the outcome of interest in each exposure level. The slopes for specific disease subgroups contribute to the overall slope in an additive manner, and measures based on the individual slopes can be used to assess the relative strengths of the trends for specific disease subgroups as well as their relative contributions to the overall trend. This approach is illustrated with data on social class patterns of mortality in New Zealand males aged 15-64 years during 1974-1978; it is shown that the strongest mortality gradients were for mental disorders, infectious diseases, respiratory diseases, and accidents. The latter two categories together accounted for approximately two thirds of the overall social class mortality gradient.

Adolescent↗
PubMedDate not supplied

Epidemiologic designs for the study of acquired immunodeficiency disease: options and obstacles.

Epidemiologic methods are designed to identify risk factors involved in production of a particular disease, even when the specific etiologic agent is unknown. However, a major problem currently presenting obstacles to research on the acquired immunodeficiency syndrome (AIDS) relates to classification; approaches are described that will permit reclassification when better laboratory techniques are developed or when more information is available from studies on natural history. Further descriptive studies will be valuable in the determination of whether extension of disease has occurred to new population groups or geographic areas. Case control studies can provide information on changes of known risk factors or can confirm and help to specify those factors already recognized. Because of the dynamic nature of AIDS and the probable existence of multiple risk factors, prospective cohort studies will be of greatest value, although they will take longer to complete. As understanding of the etiologic factors improves, preventive measures will become more efficient.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Poisoning and epidemiology: 'toxicoepidemiology'.

1. There is little hypothesis-testing clinical research performed in toxicology. Randomized clinical trials are rare and most observational studies are performed on highly selected patients and are subject to marked bias. Thus, for many poisonings, our approach has been based almost entirely on deduction from known pharmacological/toxicological effects, generalizations from drugs within the same therapeutic class, animal data and case reports. This is also far from satisfactory, as many toxicological mechanisms are poorly understood and not related to the therapeutic class. 2. Although we need much better data to address the clinical and public health aspects of poisoning, there are many practical and ethical reasons why randomized clinical trials are difficult in this field. However, the scope for observational research, in particular population-based clinical epidemiology, is almost unlimited. The collection of data on human poisoning is facilitated because most non-fatal overdoses are admitted to hospital and by legal requirements to report to the coroner deaths that are due to poisoning. In the present article I argue that 'toxicoepidemiology', meaning the application of epidemiological methods to the problem of acute poisoning, is the best means we have of addressing deficiencies in our knowledge of poisoning. 3. Examples are given of a variety of observational research strategies, ranging from audit to meta-analysis, that may be applied to clinical toxicology. From coronial and clinical data obtained from reasonably well-defined populations, it has been possible to identify a number of previously unrecognized differences in the severity and spectrum of toxicity between and within drug classes. Also, the demographic risk factors for poisoning and the reproducibility, validity and optimal use of diagnostic and therapeutic interventions can be assessed. 4. The major limitations to the range of associations and interventions that may be studied are the need to achieve adequate power to study uncommon outcomes or poisonings and the ability to replicate findings at other centres using similar methodology. The expansion of data collection to other centres has the potential largely to overcome these obstacles.

Clinical Trials as Topic↗
PubMed1985

Evaluating cancer clusters.

We have had considerable success in identifying cancer causing agents in the workplace using epidemiologic methods. This success had made us very sensitive to the occurrence of cancer clusters among workers in the belief that identification of some common exposure could reveal the presence of a carcinogen and lead to preventive measures. This intense surveillance is both a blessing and a curse. On the one hand, it is a proven way of discovering environmental causes of cancer. On the other, it leads to false alarms or does not always lead to identification of a causal agent. It is easy to demonstrate, using tables of random number 5, how clusters can occur by chance and to demonstrate that when the number of comparisons made in identifying clusters is known there is a basis for their evaluation. Unfortunately, in most instances, when cancer clusters are detected in the workplace the number of comparisons made is unknown and the statistical significance of the cluster cannot be evaluated. Moreover, it is not usually recognized that in this situation when a study is made as a result of discovering a cluster in a particular population, the cases that make up the cluster cannot be included in a data set which tests the hypothesis that a cluster exists. This paper illustrates the above points by actual experiences.

Epidemiologic Methods↗
PubMedDate not supplied

A nested-epidemic model for the spread of hepatitis C among injecting drug users.

Injecting drug users (IDUs) are the largest risk group for HCV infection. Studying injecting by classical epidemiological methods is no easy task, largely due to its hidden nature and low prevalence in general population terms. Thus, mathematical modelling can be of major help in performing a qualitative and quantitative evaluation of the costs and possible impact of the various interventions and to produce forecasts of both injecting drug use and HCV spread among IDUs. In the present paper an epidemic Mover-Stayer model for the spread of drug use, which has been recently proposed, is extended to mirror the spread of an infectious disease, in particular hepatitis C, among the injecting drug user population. In order to model the spread of a disease (HCV) among a population evolving following a different epidemic (injecting drug use) all the compartments of the 'external epidemic' (injecting drug use) are subdivided into two sub-compartments: the first one comprising individuals who are not affected by HCV and the second one comprising individuals affected. The resulting model may be defined the 'two epidemics' or, better, the 'nested epidemics' model. The model is a Mover-Stayer model for what concerns the 'external epidemic' (injecting drug use) but is a homogeneous epidemic model for HCV (all individuals are at risk of HCV the same). In the following, the dynamic equations are derived. Some qualitative analysis is performed in order to evaluate the asymptotic behaviour and the impact of possible prevention or harm reduction interventions. The results of a scenario analysis are also presented. The model, though simple, seems to be a very valuable tool for policy makers.

Disease Outbreaks↗
PubMedDate not supplied

[Carcinogenic risk and epidemiology: thoughts on experience in the tanning and shoe industries].

An epidemiological method is described that was applied to the study of cancer risk in tanning and shoe industries. The limitations of the epidemiological research carried out so far are stressed and priorities are discussed. In particular, methods for the surveillance of cancer risk need to be implemented and etiological studies with adequate statistical power should be planned for the future.

Epidemiologic Methods↗
PubMed1995

Errors in exposure assessment, statistical power and the interpretation of residential radon studies.

To date, epidemiological studies of risk from residential radon have not convincingly demonstrated an association with lung cancer. These case-control studies, however, have inherent limitations due to errors in estimates of exposure to indoor radon. These errors take on special significance because the level of residential risk predicted from studies of underground miners is relatively low and possibly at the limit detectable by current epidemiological methods. To illustrate the problem caused by errors in exposure assessment, a series of case-control studies were simulated and resulting dose-response relationships evaluated. For each of four assumed error distributions for exposure to radon progeny, 10 indoor radon studies of 700 cases and 700 controls were generated randomly from a population with a risk of radon-induced lung cancer based on extrapolations from studies of underground miners. When exposures were assumed as known without error, 6 of 10 studies failed to find a significant dose response, in accord with the theoretical power of the study of 0.47. For simulations in which exposures were measured with error, the situation was worse, as the power of the study was reduced further and it was even less likely that a single study would result in a significant finding. For each error scenario, combining data from the 10 simulated studies did result in a significant dose response. However, the pooled results are somewhat misleading, because the effects of mobility, missing radon measurements, residential occupancy and potential confounding variables such as cigarette smoking were not taken into account. Empirical estimates of power were computed using 1,000 simulated case-control studies. When mobility and missing radon measurements in prior homes were incorporated into the design, the power of the study decreased, reducing the chance of detecting a significant effect of exposure. Enlarging study size to 2,000 cases and 2,000 controls increased the power of the study to 0.90 when exposure error was absent and subjects lived in one home only, but power was below 0.40 under realistic conditions for exposure error and mobility. When studies were generated under an assumption that exposure does not increase risk, up to 15% of simulated studies with 700 cases and 700 controls resulted in an estimated dose-response parameter in excess of the dose response from studies of miners. With increasing mobility and exposure error, it became virtually impossible to distinguish between the distributions of risk estimates from simulated studies based on an underlying excess relative risk of 0.015/working level month from estimates based on no risk from exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Case-Control Studies↗