EPIDEMIOLOGY PRINCIPLES OF EPIDEMIOLOGY HW 3

EPIDEMIOLOGY PRINCIPLES OF EPIDEMIOLOGY HW 3

EPIDEMIOLOGY PRINCIPLES OF EPIDEMIOLOGY HW 3

Read the scenario below and complete the assignment as instructed.

Scenario

In Community X (population 20,000), an epidemiologist conducted a prevalence survey in January of 2012 and reported an HIV prevalence of 2.2%. Over the next 12 months, the department of health reported an additional 50 new HIV cases between February 2012 and January 2013. The total population stayed constant at 20,000.

Part 1

How many people had HIV in January 2012? Present or describe the formula you used to arrive at your answer.
Calculate the incidence rate assuming no HIV-related deaths over the 12-month period. Present or describe the formula you used to arrive at your answer. Be sure to clearly indicate the numerator and denominator used in your calculation and include an appropriate label for the rate.
In a summary of 200-250 words, interpret the results and discuss the relationship between incidence and prevalence. Discuss whether or not the epidemiologist should be concerned about these new HIV infections, assuming a previous incidence rate of 0.5 per 1,000 person-years prior to this updated risk assessment.

Part 2

A rapid test used for diagnosing HIV has a sensitivity of 99.1% and a specificity of 90%. Based on the population prevalence of 2.2% in 2012, create a 2×2 table showing the number of true positives, false positives, false negatives, and true negatives. Calculate the positive predicative value and negative predictive value for this test. Refer to the “Creating a 2×2 Contingency Table” resource for guidance.

In 200-250 words, discuss whether or not the epidemiologist should recommend this test as part of a universal HIV screening program. Provide rationale for your recommendation applying the positive and negative predictive values. Present or describe the formula you used to arrive at your answer.

STUDY MATERIALS

Read Chapters 14 and 15 in Gordis Epidemiology.

Read “Association or Causation: Evaluating Links Between ‘Environment and Disease,'” by Lucas and McMichael (2005), located on the World Health Organization website. URL: https://www-ncbi-nlm-nih-gov.lopes.idm.oclc.org/pmc/articles/PMC2626424/pdf/16283057.pdf

Read “Weak Associations in Epidemiology: Importance, Detection, and Interpretation,” by Doll, from Journal of Epidemiology (1996). URL: https://www.jstage.jst.go.jp/article/jea1991/6/4sup/6_4sup_11/_pdf

Read “Causal Inference Based on Counterfactuals,” by Hofler (2005), located on the BioMed Central website. URL: https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-5-28

Read “Multicausality: Confounding,” by Schoenbach (2004), located on the Epidemilog.net website. URL: http://www.epidemiolog.net/evolving/Multicausality-Confounding.pdf

View “Sensitivity and Specificity – Explained in 3 Minutes,” by Martin (2014), located on the YouTube website. URL: https://www.youtube.com/watch?v=FnJ3L-63Cf8

View “The Relationship Between Incidence and Prevalence,” by Patwari (2013), located on the YouTube website. URL: https://www.youtube.com/watch?v=1jzZe3ORdd8

Use the “Creating a 2×2 Contingency Table” resource to assist with the completion of the Measuring Morbidity: Prevalence and Incidence assignment, as needed.

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You must proofread your paper. But do not strictly rely on your computer’s spell-checker and grammar-checker; failure to do so indicates a lack of effort on your part and you can expect your grade to suffer accordingly. Papers with numerous misspelled words and grammatical mistakes will be penalized. Read over your paper – in silence and then aloud – before handing it in and make corrections as necessary. Often it is advantageous to have a friend proofread your paper for obvious errors. Handwritten corrections are preferable to uncorrected mistakes.

Use a standard 10 to 12 point (10 to 12 characters per inch) typeface. Smaller or compressed type and papers with small margins or single-spacing are hard to read. It is better to let your essay run over the recommended number of pages than to try to compress it into fewer pages.

Likewise, large type, large margins, large indentations, triple-spacing, increased leading (space between lines), increased kerning (space between letters), and any other such attempts at “padding” to increase the length of a paper are unacceptable, wasteful of trees, and will not fool your professor.

The paper must be neatly formatted, double-spaced with a one-inch margin on the top, bottom, and sides of each page. When submitting hard copy, be sure to use white paper and print out using dark ink. If it is hard to read your essay, it will also be hard to follow your argument.

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