BioStat Lec

• Epidemiology flourished as a discipline in the 1940s.
• Epidemiology was originally concerned with the investigation and management of epidemics of communicable diseases.
• Lately, Epidemiology was extended to endemic communicable diseases and non-communicable infectious diseases.
• Person B had disease Y and has factors W and V.
• Person A has disease Y and has factors X, W and V.
• Whatever phenomenon varies in any manner, whenever another phenomenon varies in some particular manner, is either a cause or an effect of that phenomenon, or is connected with it through some fact of causation.
• Person B has severe form of disease Y and has much factor X.
• Disease Y is caused by factor X.
• The number or rate of cases is plotted over time.
• Analysis at these shorter time periods is particularly appropriate for conditions related to occupational or environmental exposures that tend to occur at regularly scheduled intervals.
• Secular (long-term) trends in disease occurrence can be graphed by plotting the annual cases or rate of a disease over a period of years.
• An epidemic curve’s y-axis shows the number of cases, while the x-axis shows time as either date of symptom onset or date of diagnosis.
• Place of diagnosis or report, birthplace, site of employment, school district, hospital unit, or recent travel destinations are examples of places where disease occurrence can be described.
• The shape and other features of an epidemic curve can suggest hypotheses about the time and source of exposure, the mode of transmission, and the causative agent.
• Seasonality in disease occurrence can be graphed by week or month over the course of a year or more to show its seasonal pattern, if any.
• For some conditions, displaying data by day of the week or time of day may be informative.
• Describing the occurrence of disease by place provides insight into the geographic extent of the problem and its geographic variation.
• Epidemiologists use a graph called an epidemic curve to show the time course of a disease outbreak or epidemic.
• Phase IV trials refer to post-marketing surveillance to collect information regarding risks, benefits, and optimal use.
• These types of trials are generally conducted when the intervention is inherently operating at a group-level (e.g., changing a law or policy) or because it would be difficult to give the intervention to some people in the group while withholding it from others.
• In contrast, group trials allocate the intervention to groups of subjects.
• Phase II trials are controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study and to determine the common short term side effects and risks.
• Phase III trials are expanded controlled and uncontrolled trials after preliminary evidence suggesting effectiveness of the drug has been obtained, and are intended to gather additional information to evaluate the overall benefit-risk relationship of the drug and provide an adequate basis for physician labeling.
• Phase I trials are initial studies to determine the metabolism and pharmacologic actions of drugs in humans, the side effects associated with increasing doses, and to gain early evidence of effectiveness; they may include healthy participants and/or patients.
• Most trials are conducted by allocating treatments or interventions to individual subjects, i.e., the treatment or intervention is allocated to individuals.
• Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
• Identifying factors associated with disease help health officials appropriately target public health prevention and control activities.
• Demographic factors such as age, race, or sex; constitutional factors such as blood group or immune status; behavior or acts such as smoking or having eaten salsa; or circumstances such as living near a toxic waste site are characteristics of analytic epidemiology.
• Experimental epidemiology involves the investigator determining through a controlled process the exposure for each individual or community, and then tracking the individuals or communities over time to detect the effects of the exposure.
• Components of an ideal epidemiologic hypothesis include cause, effect, population characterization, exposure-response establishment, and time-response relationship.
• Analytic epidemiology provides sufficient evidence to take appropriate control and prevention measures.
• The key feature of analytic epidemiology is a comparison group.
• Cross-sectional study is a type of observational epidemiology where a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously.
• Quantifying the association between exposures and outcomes and testing hypotheses about causal relationships is a crucial aspect of analytic epidemiology.
• Observational epidemiology involves the epidemiologist simply observing the exposure and disease status of each study participant.
• Cross-sectional study tends to assess the presence (prevalence) of the health outcome at that point of time without regard to duration.
• Descriptive epidemiology is a tool used to document the prevalence in a community of health behaviors, health states, and health outcomes, particularly chronic conditions.
• Intervention studies aim to test the efficacy of specific treatments or preventive measures by assigning individual subjects to one of two or more treatment or prevention options.
• Clinical trials for new drugs are conducted in phases with different purposes that depend on the stage of development.
• Clinical trials might also be distinguished based on whether they are aimed at assessing preventive interventions or evaluating new treatments for existing disease.