Epidemiology, incidence and prevalence
Epidemiology, incidence and prevalence
Basic Epidemiology, Incidence, and Prevalence Exercise
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1.What is the definition of epidemiology? |
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2.Give an example of how epidemiology is important to you in your future healthcare role. |
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3.What is the definition of surveillance? |
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4.Give an example of surveillance and how you might use it in your future healthcare role. |
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5.Define incidence and give an example in line with your response to #4 above. |
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6.Define prevalence and give an example in line with your response to # 4 above. |
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7.Compare incidence to prevalence. |
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8.What three key elements (or Epitrinity) of epidemiology, along with the case definition, are the most helpful in discerning the pattern of health events in human populations? |
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9.What is used to express the number of events in the numerator and total population in the denominator?(Prevalence is one of these.) |
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10.What is used to express the number of events in the numerator and total population and a time period in the denominator. (Incidence is one of these.) |
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Carefully read Scenario 1 below and answer questions 11-14 which follow.
Scenario 1: A team of Epidemic Intelligence Service officers from the CDC arrives in Rhode Island to assist the state health department with investigation and control of an outbreak of measles.The team is asked to include the entire state in the investigation; thus, a confirmed case of measles in this outbreak is any resident of Rhode Island with an illness clinically compatible with measles who either has a positive laboratory test for measles or is a contact of someone with a positive test.Individuals with clinically compatible illnesses who did not have laboratory confirmation and were not contacts were classified as “possible cases”.(No recovery date would mean that the individual is still sick, or did not recover during the time frame of interest. No lab or contact is a non-confirmed case and these are considered the “possible cases”. These cases are not included depending on the question being asked, specifically prevalence & incidence, because they are not confirmed with the illness.) The team members arrive in Rhode Island on March 1st and spent a month investigating.They found case information as detailed in the chart below.
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Case # |
RI resident |
Onset date |
Recovery date |
Lab confirmed |
Contact |
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1 |
Yes |
2/4/2015 |
2/19/2015 |
X |
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2 |
No |
2/18/2015 |
2/22/2015 |
X |
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3 |
Yes |
2/18/2015 |
3/2/2015 |
X |
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4 |
No |
2/18/2015 |
3/2/2015 |
X |
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5 |
Yes |
2/19/2015 |
3/6/2015 |
X |
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6 |
No |
2/20/2015 |
2/27/2015 |
X |
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7 |
Yes |
2/20/2015 |
3/6/2015 |
X |
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8 |
Yes |
2/20/2015 |
3/9/2015 |
X |
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9 |
Yes |
2/23/2015 |
3/9/2015 |
X |
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10 |
Yes |
2/23/2015 |
3/10/2015 |
X |
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11 |
Yes |
2/23/2015 |
3/15/2015 |
X |
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12 |
Yes |
2/23/2015 |
3/29/2015 |
X |
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13 |
Yes |
2/24/2015 |
3/29/2015 |
X |
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14 |
Yes |
3/7/2015 |
3/18/2015 |
X |
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15 |
Yes |
3/7/2015 |
3/19/2015 |
X |
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16 |
Yes |
3/7/2015 |
3/19/2015 |
X |
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17 |
Yes |
3/7/2015 |
3/20/2015 |
X |
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18 |
Yes |
3/7/2015 |
3/29/2015 |
X |
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19 |
Yes |
3/7/2015 |
4/1/2015 |
X |
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20 |
Yes |
3/8/2015 |
3/17/2015 |
X |
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21 |
Yes |
3/8/2015 |
3/22/2015 |
X |
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22 |
Yes |
3/9/2015 |
3/22/2015 |
X |
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23 |
Yes |
3/11/2015 |
3/29/2015 |
X |
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24 |
Yes |
3/11/2015 |
3/29/2015 |
X |
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25 |
Yes |
3/16/2015 |
3/29/2015 |
X |
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26 |
Yes |
3/17/2015 |
3/29/2015 |
X |
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27 |
Yes |
3/18/2015 |
3/29/2015 |
X |
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28 |
Yes |
3/21/2015 |
3/29/2015 |
X |
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29 |
Yes |
3/21/2015 |
3/29/2015 |
X |
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30 |
Yes |
3/21/2015 |
3/29/2015 |
X |
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31 |
Yes |
3/21/2015 |
3/29/2015 |
X |
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32 |
Yes |
3/21/2015 |
4/1/2015 |
X |
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33 |
Yes |
3/21/2015 |
4/2/2015 |
X |
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34 |
Yes |
3/21/2015 |
4/2/2015 |
X |
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35 |
Yes |
3/21/2015 |
4/2/2015 |
X |
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36 |
Yes |
3/21/2015 |
4/2/2015 |
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37 |
Yes |
3/21/2015 |
X |
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38 |
Yes |
3/21/2015 |
X |
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39 |
Yes |
3/22/2015 |
4/3/2015 |
X |
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40 |
Yes |
3/23/2015 |
X |
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41 |
Yes |
3/23/2015 |
X |
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42 |
Yes |
3/29/2015 |
X |
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43 |
Yes |
3/29/2015 |
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44 |
Yes |
3/29/2015 |
X |
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For the purposes of this exercise, use one million for the Rhode Island state resident population, and answer the questions using confirmed cases only unless otherwise specified. Note:remember to express all rates (incidence is a rate) per unit of population and per unit of time.Prevalence (a ratio) needs only to be expressed per unit of population. |
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11.What was the prevalence of measles in Rhode Island as of March 1st? |
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12.What was the prevalence of measles in Rhode Island as of March 24th? |
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13.What was the incidence of measles in Rhode Island for March? |
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14.What would the incidence be for March if possible cases were also included? |
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Read the two PDF articles below.Fill in the blanks on the following table using the formula for determining prevalence, incidence and duration.
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Prevalence = Incidence x Duration Duration = Prevalence / Incidence Incidence = Prevalence / # Years Duration |
Prevalence and Incidence of Selected Diseases
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Disease |
Prevalence per 100,000 |
Incidence per 100,000 per year |
Years Duration |
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15. |
Epilepsy |
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30.8 |
12.2 |
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16. |
Multiple Sclerosis |
56 |
5.0 |
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17. |
Parkinson’s Disease |
157 |
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7.85 |
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18. |
Motor Neuron Disease |
7 |
1.7 |
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19. |
Central Nervous System |
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17.3 |
3.99 |
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20. |
Neoplasms |
10 |
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2 |
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Observing the data in the table above, |
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21. What interpretation of the data can you give? |
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22. What applications do you find for the clinical practitioner? |
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23. What applications do you find for the Epidemiologist regarding prevention? |
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Review Katz et al. 23 Birth Outcomes: A Global Perspectivehttps://studentconsult.inkling.com/read/jekels-epi….Then read the scenario below and answer the questions which follow.
Scenario 2: In a city of 100,000 people, there were last year 1000 deaths and 1500 live births (none were multiple births), of which 1200 infants survived to see their first birthday.Three mothers died in childbirth.Using the Week 3 PowerPoint for definitions, calculate:(http://www.columbia.edu/itc/hs/pubhealth/modules/d…)
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24.Infant mortality ratio : |
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25. Crude death rate: |
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26.Crude birth rate : |
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27.What possible conclusions could you draw from these rates, about the overall health status of people in this city?What should the interprofessional team do to help improve the situation? Be sure and support your conclusions using data. Textbook: Katz, D., Elmore, J., Wild, D., Lucan, S. (2013). Jekel’s epidemiology, biostatistics, preventive medicine, and public health (4th ed). New York, NY: Elsevier. |
