Introduction
A team of researchers conducted a cross-sectional study to investigate the relationship between taking estrogen and endometrial (lining of the uterus) cancer among persons with a uterus. They found those who had ever had a diagnosis of endometrial cancer were more likely to have taken estrogen for health reasons. The cross-sectional study used data from the 2018 NHANES. The researchers limited the analysis to the state in which their university hospital system operated.

They now plan to conduct a case control study to further investigate the relationship. Because the cancer is relatively rare and they wanted a good sample size, they plan to enroll case-patients as they are diagnosed over a 5-year period. In other words, for five years they will sit tight and every time they learn of a newly diagnosed patient, they will ask them to participate in the study. They will recruit the case-patients from the university hospital system.

The researchers are also debating about from where to find and enroll (also known as recruit) control participants. The options are 1. Recruit patients from the hospital system; 2. Recruit people from the neighborhoods of the cases.

The researchers also have two options for the timing of finding and enrolling controls: 1. They can enroll one or more control for each case at the same time as the new case is diagnosed and enrolled; 2. They can wait until the end of the 5 years and then enroll the total number of controls needed.

Use the text chapters in the learning materials to develop and support your responses. Your response will be in essay format (not bullets or numbered questions).

Initial Prompt

Why did the researchers start their investigation by using the NHANES data and a cross-sectional design?

Why did the researchers not rely on the results of the cross-sectional study results to make a conclusion about this relationship?

What made a case-control study a good next step in investigating the relationship between estrogen use and endometrial cancer?

Which option for the source of controls do you recommend, the hospital or the neighborhood, and why? Address the advantages and disadvantages of each option.

Which option for the timing of enrolling controls do you recommend, and why?

Readings

Bovbjerg, M. (2020). Foundations of epidemiology (1st ed) Oregon State University.
Chapter 4: Introduction to 2×2 Tables, Epidemiologic Study Design, and Measures of Association
Chapter 9: Study Designs Revisited

Aschengrau, A., & Seage, G. R. (2018). Essentials of epidemiology in public health (4th ed.). Jones and Bartlett Learning.
Chapter 6: Overview of Epidemiology Study Designs
Chapter 9: Case Control Studies pages 237–256 and 261–262 “Strengths and Limitations of Case-Control Studies”

Videos Required

Risk, Rate and Odds (4:59 minutes)
https://youtu.be/dWtzaKYFg00

Epidemiological Studies: A Beginners Guide (9:42 minutes)
https://youtu.be/Jd3gFT0-C4s