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PubMed1984

Epidemiology and prevention of injuries.

Injuries are the leading cause of death for ages 1 to 44 and are responsible for more years of productive life lost than any other disease. The common perception of injuries as random, unpredictable events has impeded the application of existing knowledge and technology fully capable of preventing many injuries or lessening their severity. This article explores the concept of injury control, the application of standard epidemiologic methods of investigation, the identification of high-risk groups, and the development and implementation of strategies for trauma prevention.

Accident Prevention↗

PubMed1981

Epidemiologic problems associated with exposure to several agents.

Simultaneous exposure to many potentially hazardous agents in the environment is the rule, yet there have been few studies that have addressed the issue of interactions of these agents in modifying disease outcomes, even though such interactions may potentially be important in terms of policy-making. Epidemiological methods may be an important way to identify interaction effects, especially for chronic disease outcomes. Some examples of epidemiologic investigations of this problem are given, and a matrix method used to evaluate the contribution of nineteen chemicals to the risk of liver angiosarcoma in vinyl chloride workers is discussed.

Air Pollutants, Occupational↗

PubMed1984

The use of epidemiology and clinical toxicology to assess environmental health problems.

Historically, epidemiology has played an important role in the changes that have taken place over time as epidemics of important infectious diseases have been replaced with modern epidemics of chronic, degenerative diseases such as elevated blood pressure, various types of cancers, diabetes, and stroke, among others. Two illustrations of the early uses of epidemiologic methods in investigations of disease outbreaks are described in the work of John Snow, who described outbreaks of cholera in the 1800s (1936, Snow on Cholera, Commonwealth Fund, New York), and J. Goldberger, who investigated the incidence of pellagra in the early 1900s (1964, Goldberger on Pellagra, M. Terris, ed., Louisiana State Univ. Press, Baton Rouge). The more contemporary use of epidemiology and clinical toxicology to assess the outcome of human exposure to environmental contaminants in the food supply are described for exposure to the polychlorinated biphenyls (PCBs) and to the polybrominated biphenyls (PBBs). Exposure to the PCBs has occurred in a variety of locations worldwide, with the greatest exposure taking place in individuals of many countries who consume fish and in Japan and Taiwan through contaminated cooking oil. Exposure to PBBs has essentially been limited to the State of Michigan where widespread contamination of cattle, dairy products, and poultry has taken place.

Environmental Pollutants↗

PubMed1994

Inter-country application of standard epidemiology tools in oral health.

If there is a single project which could demonstrate the intensive use of the WHO standard oral epidemiology methods which have been discussed and demonstrated in papers published elsewhere, it is the series of collaborative studies of oral health care systems referred to in brief as ICS-I and II. These consist of multi-country studies from which to assess the relative merits of different delivery systems based on interlinked clinical and sociological data for the consumer and sociological data for the provider. In both the ICS-I and II, each participating country team followed the same protocol and every effort was made to retain, for ICS-II, not only the same research strategy, but also as much of the methodology as possible. ICS-I covered the years 1973 to 1983: ICS-II began in 1988 and is due to end in 1995. A detailed description of the sampling, survey and analysis approaches is given in the first part of this article and highlights of the inter-country clinical data in the second part. Although ICS-I was hampered in its objective to compare relative strengths of delivery systems, or elements thereof, by the lack of comparative longitudinal data, its results had tremendous impact both for participating countries and others which could learn from the study findings. That impact was evident in the most practical form of wholesale changes in various systems and approaches and in application of study findings in constructing new systems. ICS-II data are intriguing both in the new examples they present and in comparisons over time, as well as in the improved methods developed as a result of lessons learned in ICS-I. The full report will be available in 1995.

Adolescent↗

PubMed2000

An overview of remote sensing and geodesy for epidemiology and public health application.

The techniques of remote sensing (RS) and geodesy have the potential to revolutionize the discipline of epidemiology and its application in human health. As a new departure from conventional epidemiological methods, these techniques require some detailed explanation. This review provides the theoretical background to RS including (i) its physical basis, (ii) an explanation of the orbital characteristics and specifications of common satellite sensor systems, (iii) details of image acquisition and procedures adopted to overcome inherent sources of data degradation, and (iv) a background to geophysical data preparation. This information allows RS applications in epidemiology to be readily interpreted. Some of the techniques used in geodesy, to locate features precisely on Earth so that they can be registered to satellite sensor-derived images, are also included. While the basic principles relevant to public health are presented here, inevitably many of the details must be left to specialist texts.

Epidemiologic Methods↗

PubMed1977

Disease-surveillance and decision-making after the 1976 Guatemala earthquake.

In the first 3 weeks after the 1976 earthquake in Guatemala a system for collecting, analysing, and disseminating information of medical importance was instituted in the disaster area. Data on cases of selected diseases, number of available hospital beds, and medical supplies were collected, and reported epidemics were investigated. The system functioned well despite the limited numbers of trained personnel. Collection and analysis were quick enough for data to be used immediately in decision-making. No epidemics of communicable diseases were observed in the affected area. The number of dog bites in Guatemala City increased but no cases of rabies were reported. The success of the surveillance system in Guatemala suggests that immediate use of epidemiological methods should be an integral part of disaster relief.

Animals↗

PubMed1985

Epidemiologic studies of obesity.

Epidemiologic methods quantitatively assess the relations between body weight and general or cause-specific morbidity and mortality. This research is especially difficult because of the complex interrelations between weight and diet, physical activity, cigarette smoking, blood pressure, diabetes, ischemic heart disease, and other conditions. The interactions are not easily summarized with available mathematical models. Weight may be either a dependent or an independent variable, according to the analysis. Epidemiologic studies of body weight are subject not only to biases of sampling and selection, but also marked difficulties in definition and measurement. There are variations of interpretation, sometimes even of the same set of data. However, epidemiology continues to uncover important information that is consistent across studies, and that may be used to formulate programs for disease prevention.

Body Height↗

PubMed1985

Uses of the case-control and cohort epidemiological approaches in pediatric practice and research.

Increasing reliance is being placed on the use of quantitative epidemiological methods in the conduct and evaluation of pediatric research. The basic design features of two common types of observational studies, the case-control study and the cohort study, are reviewed. Advantages and disadvantages of these two study designs are discussed with emphasis on aspects such as the selection of comparison groups, avoiding selection and recall bias, gathering exposure information, controlling for potentially confounding factors, and methods of analysis. Appreciation of the salient features of these study design approaches should aid the clinician/researcher in the conduct of research endeavors as well as in critically reviewing the medical literature.

Adolescent↗

PubMed1993

Application of epidemiologic principles and methods to investigating and controlling equine infectious diseases.

Epidemiology is a tool much like any other diagnostic tool that the practitioner uses as an aid in the complete physical examination of the group of animals. It can be used to generate a specific differential diagnosis list. Epidemiology is especially useful to design a disease control and prevention program by helping to elucidate the key determinants of disease occurrence.

Animals↗

PubMed2006

Risk adjustment and outcome research. Part I.

OBJECTIVE: The increasing demand for comparative evaluation of outcomes requires the development and diffusion of epidemiologic research, the ability to correctly formulate hypotheses, to conduct analyses and to interpret the results. The purpose of this paper is to provide a detailed but easy-reading review of epidemiologic methods to compare healthcare outcomes, particularly risk-adjustment methods. METHODS: The paper is divided into three parts. Part I describes confounding in observational studies, the ways confounding is identified and controlled (propensity adjustment and risk adjustment), and the methods for constructing the severity measures in risk-adjustment procedures. CONCLUSIONS: It is becoming increasingly important for policy makers and planners to identify which factors may improve or worsen the effectiveness of treatments and services and to compare the performances of providers. Politicians, managers, epidemiologists, and clinicians should make their decisions based on the validity and precision of study results, by using the best scientific knowledge available. The statistical methods described in this review cannot measure 'reality' as it 'truly' is, but can produce 'images' of it, defining limits and uncertainties in terms of validity and precision. Studies that use credible risk-adjustment strategies are more likely to yield reliable and applicable findings.

Confounding Factors, Epidemiologic↗

PubMed2001

Counter-matching in studies of gene-environment interaction: efficiency and feasibility.

The interest in studying gene-environment interaction is increasing for complex diseases. However, most methods of detecting gene-environment interactions may not be appropriate for the study of interactions involving rare genes (G:) or uncommon environmental exposures (E:), because of poor statistical power. To increase this power, the authors propose the counter-matching design. This design increases the number of subjects with the rare factor without increasing the number of measurements that must be performed. In this paper, the efficiency and feasibility (required sample sizes) of counter-matching designs are evaluated and discussed. Counter-matching on both G: and E: appears to be the most efficient design for detecting gene-environment interaction. The sensitivity and specificity of the surrogate measures, the frequencies of G: and E:, and, to a lesser extent, the value of the interaction effect are the most important parameters for determining efficiency. Feasibility is also more dependent on the exposure frequencies and the interaction effect than on the main effects of G: and E: Although the efficiency of counter-matching is greatest when the risk factors are very rare, the study of such rare factors is not realistic unless one is interested in very strong interaction effects. Nevertheless, counter-matching appears to be more appropriate than most traditional epidemiologic methods for the study of interactions involving rare factors.

Case-Control Studies↗

PubMed1980

The transmission of leprosy in man.

Existing clinical, scientific, and epidemiological knowledge on the mode of transmission of human leprosy is reviewed under the following headings: a. The release of viable organisms from the host into the environment. b. The presence of viable organisms so released into the environment. c. Entry into the new human host and distribution within the body. d. Production of clinical illness. It is concluded that much of the published evidence deals with one, or rather few, parameters, whose relationship to the overall scheme of transmission is uncertain. Although it is beyond doubt that most leprosy bacilli emerge from the nose and nasal secretions, probably entering the environment in droplets, little is known of their mode of survival in the environment or their entry into the new host. Existing data certainly does not provide a full "model" of leprosy transmission, and it is suggested that further work attempting to clarify the relative importance of the component events in transmission may have to rely increasingly on epidemiological methods. It also emerges that consideration of the immunological factors bearing on whether or not infections causes clinical illness is important in elucidating the mechanism of leprosy transmission. Thus even the most "applied" and practical of problems must eventually turn to the realm of "pure" research for a definitive solution.

Animals↗

PubMed1982

A review of the epidemiologic studies of toxic shock syndrome.

In response to case reports of toxic shock syndrome, six case-comparison studies were done in 1980. Early cases were predominantly in menstruating women, and the use of tampons was strongly associated with the onset of illness. Because of the widespread publication of this finding, the case-comparison studies had problems due to differential ascertainment and recall bias. However, the number of cases among women was so great and the relation with tampon use so marked that unreasonable assumptions are necessary if the results are to be attributed to these biases. The studies show the power of epidemiologic methods, even given the unfavorable circumstance of an uncommon condition, associated with a common practice. Although the absolute risk of toxic shock syndrome is small, tampon users have more than a tenfold excess risk of the condition over women not using tampons, and the use of tampons is an adequate explanation for the excess risk of women over men.

Epidemiologic Methods↗

PubMed1997

STD rapid assessment in Rwandan refugee camps in Tanzania.

OBJECTIVE: To obtain baseline information on sexually transmitted diseases (STDs) in the Rwandan refugees camps in Tanzania, prior to establishment of STD services. SETTING: The largest camps of Rwandan refugees in the Ngara District of Tanzania (estimated population 300,000). The study was carried out in 8 days in August 1994. SUBJECTS AND METHODS: A rapid assessment technique was used to measure STD prevalences among: (i) 100 antenatal clinic attenders (ANC); (ii) 239 men from outpatient clinics (OPD); and (iii) 289 men from the community. Interviews (by questionnaire) and genital examination were performed for all participants; sampling for females included genital swabs for the the diagnosis of Neisseria gonorrhoeae (NG), Candida albicans (CA), Trichomonas vaginalis (TV), bacterial vaginosis (BV) and a blood sample for syphilis serology. Men provided urine samples which were screened for leucocytes using the leucocyte esterase (LE) dipstick; urethral swabs for Gram stain were taken from men with a reactive LE test and from those with symptoms or signs of urethritis. OPD males provided a blood sample for syphilis serology. RESULTS: All groups reported frequent experience with STDs and engaging in risky sexual behaviour prior to the survey. During the establishment of the camps, sexual activity was reportedly low. Over 50% of ANC attenders were infected with agents causing vaginitis (TV/BV/CA) and 3% were infected with NG. The prevalence of active syphilis was 4%. In the male outpatients, the prevalence of urethritis was 2.6% and of serological syphilis was 6.1%. Among males in the community, the prevalence of urethritis was 2.9% (the majority being asymptomatic infections). We noted frequent over-reporting of STD symptoms, unconfirmed clinically or biologically. CONCLUSIONS: STD case detection and management should be improved by training health workers in using the WHO syndromic approach, and through IEC campaigns encouraging attendance at clinics. Rapid epidemiological methods provide quick and useful information at low cost in refugee camps.

Adolescent↗

PubMed1984

Towards the dietary prevention of cancer: contributions of epidemiology.

There may be a considerable potential for the prevention of cancer through dietary modifications or chemo-prevention strategies. The epidemiological methods which have been used in the study of the relation between diet and cancer are briefly reviewed and the scientific basis for major hypotheses linking diet to cancer are summarized. Clinical trials, now being considered to assess the potential for the prevention of cancer by dietary supplementation or modification, do not have many of the uncertainities of other methods, yet there are many potential difficulties in both the conduct and interpretation of such trials. These limitations are discussed as well as the problem in making general dietary recommendations for the prevention of cancer based on current knowledge. A more complete understanding of the effect of diet on cancer risk will likely emerge only through a more integrated and interdisciplinary approach in future studies.

Ascorbic Acid↗

PubMed1985

The use of epidemiology, scientific data, and regulatory authority to determine risk factors in cancers of some organs of the digestive system. 1. Introduction.

Continuing concern about cancer provides an impetus for continuing efforts to reduce its incidence and improve its treatment. Efforts to improve treatment are seen as highly desirable and excite little controversy, but attempts to reduce cancer incidence by regulatory intervention raise questions about cost-benefit ratios. Difficulties of making cost-benefit decisions are compounded by the lack of adequate data, especially in the area of cancer incidence and mortality, to demonstrate that regulatory or program intervention has effected any improvement. Regulatory agencies such as Food and Drug Administration can use descriptive epidemiological methods to determine trends in disease and magnitudes of exposed populations largely from readily available data, e.g., mortality data, data from National Cancer Institute surveys, census data, and food consumption data. The goal of these studies is to identify any unexpected changes in incidence or mortality through surveillance of the available data for time trends and through probes of specific data collected during research activities or gathered in support of regulatory decisions.

Digestive System Neoplasms↗

PubMedDate not supplied

Sir William Petty: modern epidemiologist (1623-1687).

William Petty, physician, epidemiologist, political economist, demographer, cartographer, and administrator was an intellectual product of the seventeenth century. Petty was born in the year 1623 in Romsey, England of lower middle class parents; however, by the time of his death in 1687 he had become a knight of the realm, founder of the Royal Society, and friend of kings. Petty's life reflected the northern renaissance which induced such dramatic changes in science, technology, politics, and entrepreneurship. His education was eclectic, nonetheless he took his Doctor of Physic degree from Oxford in 1649 and became an Oxford don, where he spent the next few years as an academic before undertaking a definitive survey of Ireland on behalf of the Cromwell government. Ireland changed Petty's destiny and he became a man of the world and entrepreneur which stimulated his interest in public policy formulation and economics. It was Petty's peculiar genius to be innovative in the application of measurement, statistics, and mathematics to socioeconomic and demographic phenomena. As a physician he related his knowledge of health and disease to these phenomena in what in the modern context would be called human ecology or social epidemiology. These relationships and their measurement were employed to establish an objective set of data which could be analyzed for the purpose of rational public policy planning by the state. This scientific approach to public policy places Petty squarely in the context of modern epidemiologic and public health practice and marks the initiation of a major use of the epidemiologic method.

England↗

PubMed1988

[Determination of the risk of a 2d cancer in patients treated for a first cancer].

A paradoxical effect of radiotherapy and chemotherapy for cancer is that some of these treatments can themselves cause new cancers. Most epidemiologic methods can be applied successfully to the investigation of this problem and this paper reviews various approaches that have already been used by various researchers. The authors first review the more traditional methods, i.e., cohort and case-control studies and they then describe designs that have been proposed more recently, such as case-cohort studies. A distinction is established between internal comparisons, carried out within the study population, and external comparisons, in which a general population external to the population under study is used as the reference category. This presentation is mainly aimed at investigators using tumor registry data. However, the general principles formulated here are easily generalized to contexts other than that of registries.

Antineoplastic Agents↗