Unit 2 Assessment Questions Concepts Of Epidemiology

PUH 5303, Concepts of Epidemiology 1

Course Learning Outcomes for Unit II Upon completion of this unit, students should be able to:

5. Discuss measures of disease frequency and measures of effect in public health. 5.1 Explain the differences between risk difference and population risk difference. 5.2 Differentiate among ratios, proportions, and rates as used in epidemiology. 5.3 Describe the three main elements of descriptive epidemiology.

 

Course/Unit Learning Outcomes

Learning Activity

5.1

Unit Lesson Chapter 3 Video: Epidemiology the Backbone of Public Health Unit II Assessment

5.2 Chapter 3 Chapter 5, pp. 99–117 Unit II Assessment

5.3

Unit Lesson Chapter 5, pp. 99–117 Video: Epidemiology the Backbone of Public Health Unit II Assessment

 

Required Unit Resources Chapter 3: Comparing Disease Frequencies Chapter 5: Descriptive Epidemiology, pp. 99–117 In order to access the following resource, click the link below. Global Health with Greg Martin. (2017, July 31). Epidemiology the backbone of public health [Video file].

Retrieved from https://www.youtube.com/watch?v=S5XRh47T420&feature=youtu.be Transcript for Epidemiology the Backbone of Public Health video

Unit Lesson Introduction The interdisciplinary foundations of epidemiology are very important to public health practice. Since epidemiology draws from several different areas of science and medicine, it is important for us to understand how to use these different areas in our respective health professions. Now that we have a good understanding of what epidemiology is from Unit I, we are ready to dive into how we use epidemiology in public health. One of the most important aspects to understand about epidemiology is that the spread of disease does not happen randomly; there are patterns that occur that help track the spread of disease. There are seven attributes that we focus on when we think about the science of epidemiology.

UNIT II STUDY GUIDE

Descriptive Epidemiology, Morbidity, and Mortality

 

https://www.youtube.com/watch?v=S5XRh47T420&feature=youtu.be

https://online.columbiasouthern.edu/bbcswebdav/xid-118195432_1

 

 

PUH 5303, Concepts of Epidemiology 2

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? First, epidemiology is a science-based discipline. This attribute is useful when using epidemiology to describe the overall health of a community.

? Second, epidemiology is the foundation of public and community health because it is able to be used to track the risk factors and protective factors that are evident in different diseases and health conditions.

? Third, epidemiology deals with the distribution of disease and health conditions by person, place, and time.

? The fourth attribute of epidemiology is that it deals with the conditions, behaviors, and factors related to health and disease. This includes physical activity, sexual behaviors, safety issues, and religious beliefs, to name a few.

? The fifth attribute of focus is that epidemiology can help us identify the antecedents or determinants and causes for disease and health-related conditions.

? Sixth, epidemiology does not just deal with the health of the individual; rather, it focuses on the health of the population.

? Finally, epidemiology is used to facilitate the planning of intervention programs that can help prevent and control the spread of disease. Using the three levels of planned prevention and control (i.e., primary prevention, secondary prevention, and tertiary prevention), health professionals are able to identify health issues and create programs to bring awareness to communities and populations.

The science of epidemiology has two major branches: analytical epidemiology and descriptive epidemiology. Analytical epidemiology is the branch that investigates the causes of disease (etiology) and the relationships between putative causative factors and health conditions. In this unit, we will discuss and gain an understanding of descriptive epidemiology. We will discuss analytical epidemiology in more detail in a later unit. Descriptive Epidemiology Descriptive epidemiology is the branch of epidemiology that analyzes patterns of disease and health-related conditions and behaviors, the distribution of disease, and the rate of disease distribution according to specific characteristics of a person, place, and time. Unlike analytical epidemiology, descriptive epidemiology forms the basis for understanding patterns of disease and health-related conditions as well as how these patterns occur in populations. Descriptive studies can be population-based, individual-based, or cross-sectional surveys, to name a few. Throughout history, the use of descriptive epidemiology has contributed significantly to the success and growth of community and public health efforts. For instance, in the mid- 1700s, Sir Percivall Pott discovered a cause of scrotal cancer by observing chimney sweeps in London (Dronsfield, 2006). In the early 1900s, the main cause of death in America was infectious diseases, such as influenza and pneumonia. Using epidemiology, scientists were able to study the pattern and spread of these diseases and create a way to combat and reduce the rate of transmission, thereby creating a healthier America. As shown in the graphic above, descriptive epidemiology has three main elements: a person, place, and time. Let’s take a closer look at each element.

 

 

 

PUH 5303, Concepts of Epidemiology 3

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Person: Examining the characteristics of a person, place, and time in relation to a specific disease or health-related condition is an essential analysis in descriptive epidemiology. Epidemiologists are interested in tracking distributions for several factors related to persons. Some of those factors are age, gender/sex, race, ethnicity, religion, socioeconomic status, occupation, marital status, birth cohort, place of birth, and migration. Of the many factors that are considered, age is the most important because it is linked with significant changes in disease rates, and the occurrence of diseases typically increases with age (Aschengrau & Seage, 2020). Also, some diseases and health-related conditions are age-specific. For example, measles and chicken pox are typically childhood diseases. On the other hand, violence and substance abuse are more common among teens. Chronic diseases, such as cancers, cardiovascular diseases, and mental disorders, are more common among older adults. Morbidity and mortality rates are also factors to consider when focusing on the age of a person in descriptive epidemiology.

Race and ethnicity are also major indicators of health. The United States is a melting pot for immigrants from countries such as Africa, India, Japan, Mexico, and Iraq, to name a few. With the continuous flow of people, there is also a flow of new diseases that are typically indigenous to those specific groups. At this time, 12 racial groups are identified by the 2010 U.S. Census, which include White, Black or African American, American Indian, Chinese, Filipino, Japanese, Korean, Vietnamese, Native Hawaiian, Samoan, and Guamanian or Chamorro (Aschengrau & Seage, 2020). The 2010 U.S. Census also identifies people of Hispanic, Latino, or Spanish origin, which is separate from the racial category. Certain health conditions are linked to people of a specific race and ethnicity. For instance, people of African American and Mediterranean descent are more likely to suffer with sickle cell anemia or to have the sickle cell trait. African Americans and Mexicans have a higher rate of type 2 diabetes than Whites. Also, Ashkenazi Jews are more likely to be diagnosed with Tay-Sachs disease, and African American men are more likely to die of prostate cancer than any other racial group (Aschengrau & Seage, 2020). Studying trends in mortality can tell health professionals about the progress of medicine over time and the public health measures that can be taken to reduce the spread of disease. Much of the morbidity and mortality rates and statistics are based on results from descriptive epidemiology.

Place: Health conditions and spread of diseases vary from place to place. The variations can occur between countries, states, rural and urban areas, neighborhoods, and even cities and countries. Place can be thought of in terms of geographical areas or physical, social, and biological environments. The physical environment can include the climate, weather, air, and water. The biological environment includes vegetation and wildlife, and the social environment includes cultural and religious traditions. Some health conditions and diseases are specific to certain places. For example, malaria mostly occurs in areas of the world where the physical environment is favorable for the life cycle of the Anopheles mosquito. Therefore, areas such as Southeast Asia, Central America, and northern South America have a higher prevalence and transmission of malaria than other areas such as Alaska or Russia. Rates of chronic disease such as liver cancer is more prevalent in males who live in Eastern Asia than those who live in South-Central Asia (Aschengrau & Seage, 2020).

Epidemiologists are able to investigate the effect of place on the occurrence of disease using migrant studies. These studies track and compare the rates of disease among natives of a particular place to the rates of immigrants in their new country (Aschengrau & Seage, 2020). For instance, a migrant study would be used to track the incidence of cancer among Japanese in Japan and Japanese who migrate to Hawaii.

(Mott, 2019)

(Capturing the Human Heart, 2018)

 

 

 

PUH 5303, Concepts of Epidemiology 4

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On the other hand, localized studies can be conducted to compare morbidity and mortality rates of populations between rural and urban areas, for example. It has been found that urban areas have higher rates of bladder, lung, liver, and oral cancer than rural areas. Spatial epidemiology studies the special distribution of diseases and health conditions in a geographical environment. It involves mapping the position of disease cases and investigating the disease based on spatial statistical methods. For instance, John Snow used spatial mapping when he studied the cholera outbreak in London (Dempsey, 2013). Spatial epidemiology is important because it identifies sources of disease and identifies disease patterns. These two pieces of information can be used to target specific interventions that will directly influence a particular geographic area.

Time: As we discuss time in epidemiology, we are referring to cyclic fluctuations, point epidemics, secular trends, and clustering (Friis & Sellers, 2014). We can gain valuable information from analyzing the changes of disease and health conditions as well as death rates during a span of years, months, weeks, days, and even hours. With this information, we can plan for causal research and public health planning and evaluation to combat disease occurrence. Epidemiologists and health professionals can use time to track disease trends. Secular trends, also called temporal trends or long-term trends, are the longest trends in epidemiology that influence disease and health conditions over time. Secular trends are changes in diseases and health conditions that typically occur over decades. The study of changes and conditions of Alzheimer’s disease over a span of 10 years can be considered a secular trend. Short-term trends or seasonal fluctuations, on the other hand, are used to examine infectious diseases such as Legionnaires’ disease or influenza that occur during specific times of the year or during different seasons.

Time trends demonstrate changes in exposure and susceptibility of disease due to fluctuations occurring on an annual, weekly, or daily basis. Understanding these trends allow us to learn what factors are responsible for a particular increase or decrease in disease or health condition. Disease Frequency Disease frequency refers to the number of new cases of a disease and the duration of the disease. Disease frequency is a mathematical measurement applied to control and prevent health problems in a population. We can also use disease frequency to study the historical patterns of disease and apply those trends to current and future trends within a population. A population is a group of people who have certain characteristics in common. For example a population can be a group of people who all live in the same geographical area such as Montgomery, Alabama, or a group of people who all work at a particular place. Population can also be described as a group of people who have a life event in common. For example, all of the soldiers who fought in Operation Desert Storm in 1990 are a

population. Likewise, all of the babies born on New Year’s Eve in 2018 are also a population. As you continue to read this lesson, you will see the terms incidence, which is the number of new cases occurring during a particular period of time, and prevalence, which is the actual number of live cases during a period of time or at a particular point in time. These are the two basic measurements that are used to describe disease frequency.

We can compare disease frequencies using a two-by-two table of incidence or prevalence data, such as the one shown below. This table contains two categories of exposure and two categories of disease.

(Tyson, 2018)

 

 

 

PUH 5303, Concepts of Epidemiology 5

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In our two-by-two table above, the cell a + b + c + d is the total number of participants in the study population.

? The total number exposed to a disease is indicated by the cell a + b, and the total number who were unexposed are indicated in the cell c + d.

? The total number of participants who are diseased is represented in cell a + c, and the total number of non-diseased participants is in cell b + d.

? The number of participants who were exposed and diseased is represented in cell a; the number of participants who were exposed but not diseased is represented in cell b; the number of participants not exposed but diseased, such as people who genetically inherited a disease, is represented in cell c; and the number of participants who were neither exposed nor diseased is represented in cell d.

Measures of disease frequency are compared using absolute comparisons or relative comparisons. Absolute comparison or risk difference (RD) is the risk of disease associated with the population who are exposed. Population risk difference (PRD) is the term used to describe the impact of exposure to a disease in an affected population. The PRD helps public health officials identify the specific exposures and to prioritize prevention implementations within that population. Relative measures use the ratio of two measures of disease frequency in the unexposed population to determine the risk ratio and allow public health professionals to compare the strength of the relationship between the exposed population and the disease. This kind of measurement is very beneficial in etiologic research studies.

References Aschengrau, A., & Seage, G. R., III. (2020). Essentials of epidemiology in public health (4th ed.). Burlington,

MA: Jones & Bartlett Learning. Capturing the Human Heart. (2018). Travel, pin, planning and map [Photograph]. Retrieved from

https://unsplash.com/photos/TrhLCn1abMU Dempsey, C. (2013). John Snow’s cholera map using GIS data. Retrieved from

https://www.gislounge.com/john-snows-cholera-map-gis-data/ Dronsfield, A. (2006). Percivall Pott, chimney sweeps and cancer. Retrieved from

https://eic.rsc.org/feature/percivall-pott-chimney-sweeps-and-cancer/2020205.article Friis, R. H., & Sellers, T. A. (2014). Epidemiology for public health practice (5th ed.). Burlington, MA: Jones &

Bartlett Learning. Mott, J. (2019). Crowd, audience, person and stadium [Photograph]. Retrieved from

https://unsplash.com/photos/hLKCGM_xEog Tyson, J. (2018). Gauge, time, clock, and clock face [Photograph]. Retrieved from

https://unsplash.com/photos/FlHdnPO6dlw

 

 

 

PUH 5303, Concepts of Epidemiology 6

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Suggested Unit Resources Some pages in Chapter 5 of the textbook are required reading, but reading the rest of the chapter is recommended. Chapter 5: Descriptive Epidemiology, pp. 118–145 In order to access the following resources, click the links below. The following video segment discusses how epidemiology was applied to determine causes of cancer and discusses the behaviors of cancer and gives a historical perspective. Burns, K. (Producer). (2015). Epidemiology (Segment 17 of 37) [Video file]. Retrieved from

https://libraryresources.columbiasouthern.edu/login?auth=CAS&url=https://fod.infobase.com/PortalPl aylists.aspx?wID=273866&xtid=93452&loid=367683

The transcript for this video can be found by clicking the “Transcript” tab to the right of the video in the Films on Demand database. The Tigray region conducted research on almost 67,000 cases of hypertension and found that the overall trend of hypertension mortality has decreased over the years. Although the mortality rate has been decreasing for hypertensive patients in the region, morbidity remains an issue. Gerensea, H., & Teklay, H. (2018). Trend of hypertension morbidity and mortality in Tigray Region from 2011

to 2015, Tigray, Ethiopia.BMC Research Notes, 11(1), 1–5. Retrieved from https://link.gale.com/apps/doc/A546892973/AONE?u=oran95108&sid=AONE&xid=10f2e86f

 

Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. Focused questions related to the information in the textbook are presented at the end of each chapter. Answering these questions will help you to master the information in the chapters. After you read the assigned textbook chapters for this unit, check your knowledge by completing the chapter review questions below.

? Chapter 3 Questions, pp. 73-76

? Chapter 5 Questions, pp. 150-151 Answers to the review questions are provided in Chapter 18 of the textbook. Once you have answered the questions, compare your answers to the ones provided in order to see how well you did!

 

QUESTION 1

1. There are three main elements or characteristics of descriptive epidemiology that are used to describe almost any disease or health condition: person, place, and time. Explain the significance of each element and how they are used to study the distribution and determinants of disease frequency. Your response must be at least 200 words in length.

QUESTION 2

1. Explain the similarities and differences between risk difference and population risk difference. Provide one specific example of each that you could use in a real-world scenario. Your response must be at least 200 words in length.

QUESTION 3

1. Consider the following hypothetical scenario: The Idaho Kidney Center analyzed deaths among patients with kidney disease who were seen at their program from 1/1/2006 through 12/31/2011. A total of 2,965 deaths occurred during the observation period among the 22,735 study population. The table below gives the race and gender of the decedents and the total population.

Characteristic	Decedents (N = 2,965)	Total Study Population (N = 22,735)
Gender Male Female	1,779 1,186	15,748 6,987
Race White, non-Hispanic Black, non-Hispanic Hispanic Other/Unknown	1,951 523 251 240	12,912 8,066 1,230 527

2. Using the scenario above, calculate and explain how to find the prevalence of Hispanics in the total study population. Then, calculate and explain how to find the ratio of males to females in the total study population. What is the proportion of Black, non-Hispanic decedents in this program? In addition, what is the proportion of White, non-Hispanic decedents in this study? Explain why this information is necessary for an epidemiological study. Your response must be at least 500 words in length.