PRINCIPLES OF EPIDEMIOLOGY December 18, 2020 / in Uncategorized / by developer. What has the literature said about the exposure-disease relationship? In this case, the data are “pulled” by the requestor, usually during emerging diseases or significant changes in disease incidence. One of the most basic ethical principles of medicine and epidemiology is the moral obligation to cause no harm to participants (non-malfeasance), whether physical or psychological. ETIOLOGY AND NATURAL HISTORY OF DISEASE A. The investigators jump back in time to identify a cohort of individuals at a point in time before they developed the outcomes of interest, and try to establish their exposure status at that point in time. This is important in epidemiology, because rates can be used to measure the speed of a disease event or to make epidemiologic comparisons between populations over time. Although epidemiologists and direct health-care providers (clinicians) are both concerned with occurrence and control of disease, they differ greatly in how they view “the patient.” The clinician is concerned about the health of an individual; the epidemiologist is concerned about the collective health of the people in a community or population. 6) Plausibility—A rational, explainable mechanism between cause and effect is helpful (but may be limited by current knowledge). 1. Contemp Ob/Gyn 1982;20:147–61. However, in some cases, the mere presence of the exposure, without regard to its magnitude, can trigger the effect. We handle assignments in a multiplicity of subject areas including Admission Essays, General Essays, Case Studies, Coursework, Dissertations, Editing, Research Papers, and Research proposals. 10.1: Principles of Epidemiology Last updated; Save as PDF Page ID 8686; Contributed by Boundless; General Microbiology at Boundless; No headers. Obviously, each member of the cohort must not have the disease or outcome at the beginning of the study. Because the cases have already been identified, they are appropriate for studying rare diseases and examining multiple exposures. In other words, the word epidemiology has its roots in the study of what befalls a population. If the variables are associated, that relationship can be either positive or negative. Observational studies – we do not interfere in the process of the disease, but simply observe the disease and the associated factors. • Epidemiology is the basic science of Preventive and Social Medicine. Although a higher OR indicates a stronger association between exposure and outcome, it does not necessarily imply statistical significance and, by itself, is not enough to prove causality. Greenwood M.Epidemics and crowd-diseases: an introduction to the study of epidemiology, Oxford University Press; 1935. The book emphasizes concepts and principles. I came across subsequent studies on these topics recently! Key terms in this definition reflect some of the important principles of epidemiology. The unit under study is a group of people or animals versus an individual. Principles of Epidemiology Public health workers use epidemiologic principles as the foundation for disease surveillance and investigation activities. Consider a study comparing library usage between students at two universities. In this type of study, the units are groups (or communities) of participants assigned to treatment or control conditions. Please confirm that you are a health care professional. What are the principles of nutritional epidemiology? A proportion is a type of ratio in which the numerator is part of the denominator (A/[A + B]). Dictionary of epidemiology. Explain the biological and genetic factors that affects a population’s health. Characterizing health events by time, place, and person are activities of descriptive epidemiology, discussed in more detail later in this lesson. Ideally, cases and controls should be as similar as possible in all characteristics except the outcome in order to make the comparisons simpler and more meaningful. In general, bias in descriptive studies is not as prevalent or significant as bias in analytical studies. Epidemiology is the study (scientific, systematic, data-driven) of the distribution (frequency, pattern) and determinants (causes, risk factors) of health-related states and events (not just diseases) in specified populations (patient is community, individuals viewed collectively), and the application of (since epidemiology is a discipline within public health) this study to the control of health problems. Whether an outbreak is foodborne in origin or from another infectious source, the methodology is similar. Preventing disease and promoting health. For example, in a class of veterinary students in which 88 are female and 14 are male, the sex ratio of female students to male students is 88/14, or 6.3 to 1. PPV is calculated as true positives divided by the sum of the true positives and the false positives: a/(a + b). Count health-related events 2. Epidemiology is a scientific discipline with sound methods of scientific inquiry at its foundation. In yet other cases, an inverse relationship is observed when greater exposure of a protective factor leads to lower incidence of outcomes. In epidemiology, health surveillance is accomplished in either passive or active systems. Further, at a single point in time (perhaps based on the results of a serosurvey of dogs in the practice area), 237 dogs of 6,821 dogs with active records in the practice had the disease. In medical research, these exposures typically include interventions such as vaccines, therapeutic drugs, surgical techniques, or medical devices. Screening tests tend to have higher sensitivity and lower specificity, because the purpose of such a test is to detect the maximum number of individuals with the particular disease condition. In the previous example, the incidence rate would be 13 cases per quarter/102 students, or 0.127 cases per quarter per student. History of Epidemiology. Case reports are accounts of single or a few noteworthy health-related incidents (eg, an epidemiologic description of a case of human rabies). Product code: SS-1000. The applications of epidemiology are diverse and include identifying causal mechanisms of disease, diagnostic testing, determining prognosis, and testing new treatments. Therefore, if the PPV of a test is 100%, the validity of a negative test result is still unknown. As a simple example, a study of testicular cancer among residents in a population should not include women in the population at risk (frequently expressed as the “denominator” in an epidemiologic ratio). Despite these potential limitations, detailed information regarding the dates and numbers of reported cases is visually useful. This book describes and illustrates epidemiology and its applications to policy making, health service planning, and health promotion. Significant differences might result if students from one university were queried over the phone regarding library visits, whereas students at the other university were directly observed for actual usage. Learning Objectives . A ratio is the value obtained from dividing one quantity by another (X/Y). Epidemiology according to the science of public health. What is important about your exposure? Active surveillance is usually much more expensive and labor intensive; it typically is limited to short-term analyses of high-impact events. The other category of studies that comprise analytical epidemiology are interventional studies. For example, when a patient with diarrheal disease presents, both are interested in establishing the correct diagnosis. The following steps in investigating disease outbreaks are used by the CDC: prepare for field work, confirm the existence of an outbreak, verify the diagnosis, establish a working case definition, engage in systematic case finding, apply descriptive epidemiology, develop and test hypotheses (analytical epidemiology), implement control measures, and communicate findings. January 2007; DOI: 10.1016/B978-1-4160-3167-3.50006-1. Although the communities may be selected at random, the individuals within them obviously are not. An RR of 1 means there is no difference in risk between the two groups. 0. As the investigation ensues and more information becomes available, it may be necessary to revise the case definition. Merck & Co., Inc., Kenilworth, NJ, USA is a global healthcare leader working to help the world be well. Once the null hypothesis is generated, studies are designed to test it and either reject it (by finding that some association actually does exist between exposure and disease outcome) or accept it (by finding that no association exists). Review a recent RCT conducted on the blood concentrations of active ingredients in sunscreen or the COVID antiviral therapy RCT and let me know your thoughts. An important epidemiologic concept is that neither health nor disease occurs randomly throughout populations. Epidemiology is not just “the study of” health in a population; it also involves applying the knowledge gained by the studies to community-based practice. Bias is extremely difficult to completely avoid when undertaking scientific study. A similar concept to incidence is prevalence. The group has no size limitation but must be able to be defined. The word epidemiology comes from the Greek words epi, meaning on or upon, demos, meaning people, and logos, meaning the study of. In contrast to observational studies, the investigator using an interventional approach can intentionally change some form of exposure between several groups to determine differences in outcome(s). Epidemiology is also used to search for determinants, which are the causes and other factors that influence the occurrence of disease and other health-related events. Finally, they are useful in generating information about the overall context of health, especially how it is affected by variables such as demographics, geography, and the social environment. For example, in a common point source outbreak, the investigation frequently identifies the event (eg, meal, social gathering, etc) when the exposure occurred. The most common measurement of association in case-control studies is the odds ratio. Epidemiologists assume that illness does not occur randomly in a population, but happens only when the right accumulation of risk factors or determinants exists in an individual. What has the literature said about the exposure-disease relationship? Recommend that close contacts of a child recently reported with meningococcal meningitis receive Rifampin, ____ 6. Confounding: In epidemiologic studies, a confounder is a variable that is not considered in the study design but is associated with the exposure and exerts an effect on the outcome. This book teaches its applications to population health research, policy-making, health service planning, health promotion, and clinical care. Compare frequency of brain cancer among anatomists with frequency in general population, ____ 3. Once potential associations have been observed between those who have a particular disease and those who do not, further investigations are undertaken to determine causality and identify effective interventions. Exposures typically include vulnerability factors such as a scanned copy of the field of epidemiology the... 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