POP EXAM 2 WITH COMPLETE SOLUTIONS.

Epidemiology Definition Causes, distribution, and control of disease in populations. Four Eras of Epidemiologic Thought 1) Sanitary Era - bad air or miasmas 2) Communicable Disease Era - something causes diseases (GERM THEORY) 3) Multiple Causation Era - Multiple risk factors for chronic disease 4) Eco-social - Environmental plus biological (modern thinking) Present vs Past Diseases 1900s = Communicable DZ Present = chronic diseases (Heart Disease & Cancer) Basic Epidemiologic Concepts Causality Risk Rates of occurrence Causality Based on the idea that one event is the result of another event. Links of health and illness. Hills Criteria for Causality Temporal Relationship Strength Dose-Response Relationship Consistency Plausibility Consideration of Alternate Explanations Experiment Specificity Coherence Temporal Relationship Exposure always precedes the outcome. Must be exposed to measles before getting measles Strength The greater the association between two thing the greater likelihood that that particular agent causes that condition or is cause and effect. EX: For example, people cannot develop measles without being exposed to the measles virus. ALSO: people who smoke two packs of cigarettes a day are more likely to develop lung cancer than those who smoke one pack is strong evidence for a causal relationship between smoking and lung cancer. Dose-Response Relationship increase exposure increase risk EX: Smoking 3 packs vs someone who occasionally smokes Consistency The condition occurs when factor is present not when absent. Exposure is one direction. Replication - intervention works at multiple stages. Plausibility Association agrees with currently accepted understanding of pathology. Biological Plausability - Physiologically if youre exposed to a particular chemical or virus, can we say there is a biological process that results in this condition Consideration of Alternate Explanations Simple just other options Experiment The condition can be altered (prevented or ameliorated) by an appropriate experimental regimen. Study to test hypothesis Specificity weakest criteria One Specific causes causes one specific effect For example, exposure to measles virus results only in measles, not mumps or varicella (chicken pox). Coherence The association should be compatible with existing theory and knowledge The idea that one condition causes another must be logical and should be congruent with other known facts. For example, it is known that alcohol consumption increases the time required for voluntary muscles to react to stimuli. Does it fit with our existing understanding of science and literature? John Snow Significance Era Largest Two problems of Cholera outbreak Found of Epidemiology - figured out Cholera was coming from a mofo water pump. Bacterilogic Era Plausibility & Coherence main issues. Risk Probability that a given individual will develop a specific condition Susceptibility ability to be affected by factors contributing to a particular health condition EX: Unimmunized children are susceptible to pertussis; the immunized children are not susceptible Absolute risk is the probability that anyone in a given population will develop a particular condition. Relative risk the probability that someone in a group of people with a particular characteristic will develop the condition when compared to people without that characteristic Relative Risk Numerical Indications If equal to 1: no real relationship or associated btwn exposure and condition. If 1, indicates a positive association. More exposed, the greater likelihood you will get the disease. If 1, called protective effect - if exposed to particular agent, youre actually less likely to get the disease. If RR was 0.4 then how is this interpreted? 1 - 0.4 = 0.6 or 60% - those who hate hamburger were 60% less likely to get E. Coli Rates of Occurrence Compares rates and extent of health problems in groups. Rate/Population 50/1000 vs 5,000/100,000 (A) has larger or high rate. Rate Formula # of events in a time period / population at risk at that time x 1,000 or 100,000 For example, in a community with a pop of 10,000 females age 13 to 18, there were 200 teenage pregnancies in 2010. What is the rate of teenage pregnancy? (200/10,000 ) x 1,000 ***If number of cases are so small that number is less than 1, they have you put a multiplier of 1000 or 100,000 to compare. Mortality vs Morbidity Deaths vs health conditions Mortality is ratio of the number of deaths in various categories to the number people in a given population Deaths / pop at risk x 1,000 or 100,000 Crude Death Rate Total # of Deaths / Total Population at Midyear Used to get a general health status of the community. Specific population death rate will give us more information. Survival Time Average length of time from diagnosis to death. Case fatality rate Percentage of persons with a condition who die of that condition. For example, at present many people infected with Ebola virus die because of the lack of an effective treatment and the case fatality rate for Ebola virus infection is close to 100%. Morbidity the number of persons within the population who experience a particular condition. Incidence Number of new cases of a particular condition identified during a specified time period Prevalence Total number of people affected by a particular condition at a specified time period (new + old cases) Incidence and Prevalence relationship Incidence: as incidence goes up, generally prevalence goes up as well, but may not always be true. As new cases go up, could have ppl potentially being cured from condition may die from it. But as general rule, think of it as prevalence going up with incidence. High Morbidity rate may indicate Most likely an intervention needed. primary evidence base used by population health nurses to identify health problems in the population and the factors that contribute to them Epidemiologic findings The Epidemiologic Process 1) Defining the condition - what is the issue? EX child abuse in community. What is child abuse? 2) Determining the natural history of the condition (assessment and diagnosis) 3) Identifying strategic points of control (planning) 4) Developing control strategies (planning) 5) Implementing control strategies (implementation) 6) Evaluating the effects of control strategies (evaluation) Determining the Natural History of the Condition Pyramid 1) Contributing Factors 2) Typical Signs and Symptoms 3) Effects on the Human System 4) Outcomes and factors that may affect said outcomes. 5) Frequency of occurrence. 6) Severity and Geographic Distribution Identifying Strategic Points of Control Use of knowledge of history of a disease or condition to prevent it from occurring or minimize its effects Can occur at any point of the levels of health care. 1-3 Developing Control Strats & Implementing them & Evaluate Design and implement strategies to prevent or minimize the effects of the condition on the health of the population Evaluate Here outcomes would either be the dz itself or long term sequelae of chemotherarpy is peripheral neuropathy, so maybe outcome is trying to improve the neuropathy of patients Two main factors of Epidemiologic Investigation Exposure and Outcome Epidemiologic study types Descriptive - deals with who, what, when, & where - not actually doing an intervention - no independent variable no independent variable. Only describing the situation Person - Place - Time Analytic - deals with why & how - Analytic epidemiology is the study of *factors contributing to health states.* mechanisms of causation Experimental - control group - trials Experimental vs Non Experimental? Main diff btwn experimental and non experimental design: control and experimental group, differences are bc of intervention itself. Need to have variable that is manipulated in experimental design. Types of Descriptive Epidemiologic Studies Prevalence surveys - extent of exposure of the population to risk factors in a given condition Surveillance studies Case reports Case series Cross-sectional studies Do Not Determine Causation Prevalence surveys extent of exposure of the population to risk factors in a given condition - extent of exposure Case Report in-depth information about a single instance of the condition. One person with Cancer Case Series case series is an examination of several case reports to determine common features. Several People with Cancer Surveillance studies systematic approach to monitoring trends in the occurrence of health conditions of interest. Data Cross-sectional studies Independent vs Dependent examines the extent of a health condition and exposure to its contributing factors in a given population at a given point in time collecting info about the independent and dependent variables at the same time. Independent variables: factors that can increase risk for dz and dependent is the diseased agent. Analytic Epidemiology Studies Ecological studies- compare rates of dz among several populations. Cohort studies - Follow people over time who were exposed to a supposed causative factor. Case-control studies - Comparisons between those with a disease and those without the disease. These move BACKWARD in time. Look in medical record, ask pt if they have certain exposure. EXPERIMENTAL - exposure to certain variables is manipulated. Used to test effectiveness of interventions. *Randomization Speak little to causation except for experimental!!! Ecological studies compare rates of dz among several populations. Cohort studies Follow people over time who were exposed to a supposed causative factor. Case-control studies Comparisons between those with a disease and those without the disease. These move BACKWARD in time. Look in medical record, ask pt if they have certain exposure. EXPERIMENTAL exposure to certain variables is manipulated. Used to test effectiveness of interventions. *Randomization Triad Model Data are collected with respect to a triad of elements: Host Agent Environment How these things interact or relate result in state of health or illness Infectivity agent ability to infect the body; can the agent actually enter body on its own, or does it need a vector to do it. Pathogenicity the ability of the agent to cause the disease. So even if exposed may not get it. If exposed to a cold, likely to get it, so high pathogenicity, but likely to not die from it, so low virulence. Virulence the severity of the health problems caused by the illness. So does it lead to death or chronic issues? Or is it a fairly innocuous thing like a cold and you return back to normal state of health. Toxigenicity ability of that agent to produce harmful toxins in the body to cause damage. Resistance ability to survive in these adverse conditions. Body normally mount an immune response, tries to create a bad environment to fight it off. Resistance is agent's ability to survive in the body's adverse conditions. Antigenicity ability of that agent to trigger the formation of antibodies Physical environment Weather, terrain, buildings Biological environment Plants, animals, microorganisms Socioeconomic environment Social norms, esp. r/t substance use Web of Causation Model factors are explored in terms of their interplay, and both direct and indirect causes of the problem are identified. The web of causation approach allows the epidemiologist to map the interrelationships among factors contributing to the development (or prevention) of a particular health condition. Determinants of Health Models Psychological - Stress, coping Human Behavior - risk behavior Environmental - built environment, sustainability Human Biological Determinants - Genetics, Immunity, Maturation Health System Determinants -Affordability and availability, competence, Social Determinants - social status, politics, culture, Economic - income, employment, poverty. The population health nurse is visiting the home of a family whose youngest child developed chickenpox after being exposed to a classmate with the same disease. Of which criterion for establishing a causal relationship is this situation an example? 1. Frequency. 2. Consistency. 3. Absolute risk. 4. Susceptibility. 2 4) The population health nurse is trying to identify the causative relationship for a group of school students who developed viral meningitis. Which criterion must the nurse identify to prove causation for the development of the disease in these students? 1. Coherence. 2. Specificity. 3. Consistency. 4. Temporal relationship. Answer: 4 4 The population health nurse is compiling childhood illness statistics and finds that the morbidity for chickenpox is higher for one neighborhood in comparison to the local county. What does this information mean to the nurse? 1. There are new cases of chickenpox in the neighborhood. 2. There are a larger percentage of children with chickenpox in the neighborhood. 3. A large group of children have been affected by chickenpox in the neighborhood. 4. There has been a rise in the number of children with chickenpox during a specified period of time in the neighborhood. 4 Morbidity is the ratio of the number of cases of a disease or condition to the number of people in the population. The morbidity for chickenpox indicates the total number and new cases identified during and at a specified period of time. Incidence is the number of new cases alone. The population health nurse is compiling statistics about lung cancer in one neighborhood that has experienced an average of 15 years from diagnosis to death. Which concept of epidemiology is the nurse analyzing? 1. Mortality rate. 2. Survival time. 3. Morbidity rate. 4. Survival rate. 2 The population health nurse is explaining the epidemiologic triad to a group of nursing students. What should the nurse use as an example of this triad? 1. Sun, beach, and sunburn. 2. Rural Mississippi, deer, and Lyme disease. 3. Potato salad, outdoor picnic, and food poisoning. 4. Standing water, mosquitoes, and warm weather. 3 The population health nurse is planning to use a "web of causation" to explain the development of a health problem in a group of patients. What should the nurse use as an example of the web of causation? 1. Oil refinery, flare emissions, and asthma. 2. Mosquitoes, West Nile virus, and decreased mosquito spraying. 3. Adolescent pregnancy rate, lower socioeconomic status and education, and close friends with infants. 4. Access to alcohol, decreased enforcement of minors, and attractive media portrayal of alcohol that contributes to adolescent alcohol usage. Answer: 4 Explanation: 4. Web of causation explores the influence of multiple factors on a specific health condition. The factors of access to alcohol, decreased enforcement of age checking, and the attractive portrayal of alcohol in the media contributes to adolescent alcohol usage. The other examples are of the epidemiologic triad. 4