Undertaking social and behavioural research to facilitate the design and implementation of interventions is reviewed in Chapter Quality control of all aspects of conducting a trial is crucial if the findings from the trial are to be used to make important public health decisions about the use, or otherwise, of an intervention, based on the trial results. These issues are discussed in Chapter 16 , while Chapter 17 specifically focuses on methods and quality control in field laboratories, which are an important component of most trials.
Nothing can be done without financial support for the trial. The essentials for the preparation of budgets for grant applications are given in Chapter 8. The efficient planning and management of finances during a trial are also key to success, and a requirement of funding agencies. The necessary budgeting and accounting methods are outlined in Chapter Chapter 19 affords an overview of the main methods used to assess the costs of health interventions and summarizes the types of economic analyses that can be conducted to assist decisions concerning resource allocation to health interventions.
In all but the smallest trials, substantial amounts of data are collected and have to be efficiently processed, both during the conduct of the trial and for the analysis of the results during, and at the end of, the trial. Methods of data management are summarized in Chapter 20 , and an outline of methods of statistical analysis of trials is given in Chapter In most trials it will be necessary to employ a statistician to oversee the analysis of the data from the trial, but the relatively simple methods summarized in this chapter should be sufficient to elucidate the main results from most trials.
Finally, Chapter 23 stresses the importance of communication at all stages of the trial, how best to communicate to the many different audiences who should be informed about the trial, and the necessary steps to translate research findings into policy and public health action. We have deliberately not included large numbers of references, as the book is intended to stand largely on its own, without readers needing access to a well-stocked library. Referencing has been reserved for where a particular study has been described, or as a guide for readers who may require a more detailed explanation of a concept than can be included in this text.
Whenever possible, we have favoured open access or relatively low-cost resources. This is an open access publication. Except where otherwise noted, this work is distributed under the terms of the Creative Commons Attribution NonCommercial 4. Enquiries concerning use outside the scope of the licence terms should be sent to the Rights Department, Oxford University Press, at the address above.
Monographs, or book chapters, which are outputs of Wellcome Trust funding have been made freely available as part of the Wellcome Trust's open access policy. Turn recording back on. National Center for Biotechnology Information , U. Search term. Chapter 1 Introduction to field trials of health interventions.
Scope of the book In this book, we aim to provide a practical and comprehensive guide to the design and conduct of field trials of health interventions directed against disease problems in low- and middle-income countries LMICs. Outline of contents The chapters of this book can be considered in three main groupings.
Chapter 1, Introduction to field trials of health interventions. As a result, the investigators were able to trace the chain of transmission of a unique strain of multiply antibiotic-resistant Salmonella back from the affected persons to hamburger they ate, to the meat supplier, and, ultimately, to the specific animal source herd.
This investigation played a key role in clarifying the link between antibiotic use in the cattle industry and subsequent antibiotic-resistant infection in humans. These tasks may be necessary to complete an objective, defensible field investigation, but each is also fraught with considerable ethical and legal overtones see Chapter Findings from some investigations are likely to be used as testimony in civil or criminal trials In these situations, investigations might be carried further than they otherwise would be.
For example, investigations in situations where criminal actions might be suspected to have played a role 19 might carry additional legal requirements for establishing a chain of custody of evidence, which is necessary for criminal prosecutions. The anthrax attacks during fall and related concerns about bioterrorism have stimulated other advanced and carefully designed legal measures to facilitate joint epidemiologic and criminal investigations. An example of such measures is a protocol developed by the New York City Department of Health and Mental Hygiene, New York City Police Department, and Federal Bureau of Investigation to guide in the interviewing of patients during joint investigations by public health and law enforcement professionals representing those agencies Similar collaborations exist at the federal level By analogy to clerkships in medical school and postgraduate residencies, outbreak investigations provide opportunities for training in basic epidemiologic skills.
Just as clinical training often is accomplished at the same time patient care is delivered, training in field epidemiology often simultaneously assists in developing skills in and the delivery of disease control and prevention. Changes in the epidemiologic capacities of state and local health departments 24 also highlight the need for workforce training and education on an expanded set of skills, such as bioinformatics, health economics, communications, systems thinking, and laboratory techniques.
Globally, more than 70 Field Epidemiology Training Programs have been modeled after EIS but are owned by individual countries and ministries of health. These Field Epidemiology Training Programs provide similar on-the-job training but within the context of specific cultures, partners, capacities, and public health systems An epidemiologist investigating problems in the field faces unique challenges that sometimes constrain the ideal use of scientific methods. In contrast to prospectively planned studies, which generally are based on carefully developed and refined protocols, field investigations must rely on data sources that are immediately available, less readily controlled, and subject to change with successive hours or days.
In addition to possible limitations in data sources, factors that pose challenges for epidemiologists during field investigations include sampling considerations, availability of specimens, effects of publicity, reluctance of persons to participate, and conflicting pressures to intervene.
New technologies hold the promise of mitigating some of these challenges. Field investigations often use information abstracted from different sources, such as hospital, outpatient medical, or school health records. These records vary substantially in completeness and accuracy among patients, healthcare providers, and facilities because entries are made for purposes other than conducting epidemiologic studies.
Moreover, rapid and substantive transitions have occurred for several key information sources—as, for example, in the growing use of electronic medical records, hospital and managed-care data systems, and laboratory information management systems.
These automated systems can facilitate access to needed records but might not be compatible with meeting the needs of or supporting specific record access by external investigators. Thus, the quality of such records as sources of data for epidemiologic investigations can be substantially less than the quality of information obtained when investigators can exert greater control through the use of standardized, pretested questionnaires; physical or laboratory examinations; or other prospectively designed, rather than retrospective, data collection methods.
These transitions necessitate that epidemiologists involved in field investigations increasingly might need to know how to use these data sources and, therefore, possess the requisite skills needed to analyze them.
The increasing use of social media and email can facilitate outreach to and queries of persons who might have common exposures in an outbreak situation, such as participants in an organized event linked to a common-source exposure.
Recently, social media networks have been used to assist in identifying contacts of persons with sexually transmitted diseases who might be at high risk and should be considered for targeted prophylaxis. These communication tools have provided added insight into social links and high-risk behaviors and have been used to guide and augment data collected from traditional case investigation methodologies In a planned prospective study, the epidemiologist determines appropriate sample sizes that are based on statistical requirements for power to draw conclusions about associations between exposures and health outcomes.
In contrast, outbreaks can involve a relatively small number of persons, thereby imposing substantial restrictions on study design, statistical power, and other aspects of analysis. These restrictions, in turn, place limitations on the inferences and conclusions that can be drawn from a field investigation. However, communication technologies between jurisdictions can now be used to help alleviate this problem.
For example, the electronic Epidemic Information Exchange Epi-X was developed for CDC officials, state and local health departments, poison control centers, and other public health professionals to access and share preliminary health surveillance information Although a primary motivation for this system was to enhance the recognition of multistate events or the multistate dispersion of persons with disease exposures in a single state or outside the United States, the resulting cross-jurisdictional collaboration has the additional benefit of increasing potential sample sizes for field investigations.
Because the field investigator usually arrives on the scene after the fact, collection of necessary environmental or biological specimens is not always possible. For example, suspected food items might have been entirely eaten or discarded, a suspected water system might have been flushed, or ill persons might have recovered, thereby precluding collection of specimens during the acute phase of illness when certain tests are most likely to be informative.
Under these conditions, the epidemiologist depends on the diligence of healthcare providers who are first to evaluate the affected persons and on the recall of affected persons, their relatives, or other members of the affected community.
This challenge increasingly is counterbalanced by expanding technologies in the laboratory to help in using routinely collected specimens to determine sources of outbreaks.
For example, PulseNet is a national laboratory network that enables the use of DNA fingerprinting to detect thousands of local and multistate outbreaks 28 , thereby enabling epidemiologists to rapidly implement control measures for food safety problems that would not otherwise be recognized.
As another example, in , epidemiologists investigated the largest HIV outbreak in the United States since Phylogenetic analyses of target genes within the human immunodeficiency and hepatitis C viruses enabled epidemiologists to retrospectively determine and intervene in the link between specific outbreak strains and local needle-sharing networks using contaminated equipment Acute disease outbreaks often generate considerable local attention and publicity.
In this regard, media coverage can assist the investigation by helping to develop information, identify cases, or promote and help implement control measures. Conversely, such publicity can cause affected persons and others in the community to develop preconceptions about the source or cause of an outbreak, which in turn can lead to potential biases in comparative studies or failure to fully explore alternate hypotheses.
As government employees, field epidemiologists are obligated to communicate with the public about what is known, what is unknown, and what actions are being taken to assess public health threats. Ensuring that a member of the response team has the time and skills to communicate effectively with reporters can be essential to the success of a field investigation and to disease control and prevention efforts, particularly in high-profile situations.
Frequently during the course of an event, as information unfolds and as field epidemiologists test, reject, or accept and reshape and retest hypotheses, recommendations for interventions might evolve or become more focused. Apprising affected parties and the public of the rationale for these changes is important to ensure the credibility of the field epidemiologists and of public health recommendations see Chapter In recent years, CDC and other public health agencies have used social media tools to disseminate health messages.
Although unskilled use of this medium during an ongoing investigation can pose challenges, such as spreading misperceptions or fostering information biases, social media also can be an effective means for expanding the reach of pertinent evidence-based health messages Although health departments are empowered to conduct investigations and gain access to records, voluntary and willing participation of involved parties e. In addition, persons whose livelihoods or related interests are at risk might be reluctant to cooperate voluntarily.
This reluctance often can be the case for common-source outbreaks associated with restaurants and other public establishments, in environmental or occupational hazard investigations, or among healthcare providers suspected as being sources for transmission of infectious diseases, such as hepatitis B.
When involved parties do not willingly cooperate, delays can compromise access to and quality of information e. Epidemiologists who conduct field investigations are often working in a fishbowl-type of environment. Assembled and written by experts from the CDC as well as other leading public health agencies, it offers current and field-tested guidance for every stage of an outbreak investigation—from identification to intervention and other core considerations along the way.
This manual serves as an essential, authoritative resource for epidemiologists and other health professionals working in local, state, national, and international settings for effective outbreak response to acute and emerging threats. The application period for EIS Class of is now closed. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Epidemic Intelligence Service. Section Navigation.
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