Module: Epidemiology and Statistics

Topic 6


Topic 6: How do we study the causes of disease ?

Objectives

When you have completed the reading and participated in the taught components for this week, we hope you will be able to

    • Summarise the uses and limitations of ecological studies
    • Explain the role of case control studies in investigating the causes of disease
    • Identify the main limitations and strengths of case control studies
    • Understand how odds ratios are derived and what is meant by adjusted and unadjusted odds ratios
    • Explain concepts of confounding and bias and the principles of multivariate regression analysis 

Lecture

A central aim of epidemiology is to try to identify the causes of disease so that strategies for prevention can be devised. This lecture will describe how initial clues may come from looking at the geography of disease and how hypotheses can be tested initially in a ‘quick and dirty’ fashion through ecological studies. The lecture will then focus on how the aetiology of rare diseases can be investigated more rigorously using a case-control study design. Using examples of various diseases, the talk will cover study design including pitfalls, principles of statistical analysis, and how bias and confounding need to be considered when analysing and interpreting the results of case control studies.

 

Seminar

Students will share which scientific article and accompanying media report they have chosen for their assignment. The aim of the session is to provoke further discussion of the importance of critical appraisal and how scientists and the media should try to report research responsibly.

Preparation for this week

Prepare a 5 minute presentation to the rest of the group explaining why you chose the paper and summarising the ‘bottom line’ findings as portrayed in the scientific abstract and by the media. Detailed information can be found in this handout: Student seminar preparation topic 6

These Best Practice Guidelines from the Science Media Centre for reporting science/health stories are well worth reading:

http://www.levesoninquiry.org.uk/wp-content/uploads/2012/07/Second-submission-to-Inquiry-from-Guidelines-for-science-and-health-reporting-31.05.12.pdf

Also worth browsing is Ben Goldacre’s website for amusing background and lots of examples of the poor communication of science: http://www.badscience.net. Here you can watch his excellent TED talk; his book Bad Science is also a great read.


Set Reading

 

BOOK CHAPTERS

ACADEMIC PAPERS

  • Fleming PJ, et al. Environment of infants during sleep and risk of sudden infant death syndrome: results of 1993-5 case control study for confidential inquiry into stillbirths and deaths in infancy. BMJ 1996; 313: 191-5. (Read it here)

Additional reading

  • Case control studies (chapter 6) in: Epidemiology in Medicine. CH Hennekens and JE Buring. Ed: SL Mayrent. Little, Brown and Co, Boston. (Check library availibility or buy it here)
  • Schulz KF, Grimes DA. Case-control studies: research in reverse. Lancet 2002; 359: 431-4. (Read it here)

Lecture Notes and Powerpoints