Module: Epidemiology and Statistics

Topic 4


Topic 4: Could a persistent cough be whooping cough?

Objectives

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

  • interpret a confidence interval, a P-value and a survival curve
  • describe the different ways of comparing two proportions including odds ratios
  • describe in general terms the contribution of statistics to making decisions about diagnostic tests and vaccination programmes
  • explain the common limitations of cross sectional surveys
  • describe how data on notifiable diseases are collected

Lecture: Could a persistent cough in a school child be whooping cough?

According to a study in primary care, whooping cough in children may be more common than doctors think it is and they may be failing to recognise cases. This lecture covers the study design and statistics presented in this paper including confidence intervals; significance tests, odds ratios, survival analysis and limitations of cross sectional surveys. We also begin to consider the contribution of statistics in deciding how best to make diagnoses and whether vaccination programmes should be introduced.

Seminar: Unpacking trends

In this seminar, we will begin to think about how data on trends in diseases are collected, what issues there are in collecting these data, what might contribute to the trends, and how such trends are best summarised. In addition to considering this in relation to notifiable diseases such as whooping cough, you will be introduced to cancer registries, which links with next week’s topic.

You will reinforce learning from last week’s session and this week’s lecture by summarising UK data on trends in whooping cough. You will also build on the learning in this week’s lecture by interpreting confidence intervals, P-values, and odds ratios in other research papers. 

Preparation for this week

Before the lecture

Read the BMJ article (Harnden 2006) about whooping cough and the BBC news article cited in the references. It is essential that you do this before the lecture.

Before the seminar

The BMJ article was published in 2006 and won the RCGP research paper of the year. How might this have influenced the trends observed since 2005? Find more information about the trends in whooping over time and age of sufferers from the HPA website and recent on-line news articles. You can do this between the lecture and the seminar.

Set Reading

BOOK CHAPTERS

  • Bland, M. An introduction to medical statistics. (2000) 3rd edition OUP. (Buy it or check library availability)
    • Chapter 8 on estimation describes the principles and practice of calculating confidence intervals.
    • Chapter 15, section 15.4 on sensitivity and specificity and section 15.6 on survival data 
  • Barker D, Cooper C, Rose G. Epidemiology in medical practice. (1998) Churchill Livingstone; 5th edition. Chapters 7 and 8 (Buy it or check library availability)

ACADEMIC PAPERS

  • Harnden A, Grant C, Harrison T, Perera R, Brueggemann AB, Mayon-White R, Mant D. Whooping cough in school age children with persistent cough: prospective cohort study in primary care. BMJ 2006;333:174–7 (Read it here)

  • Erickson LJ, De Wals P, Farand L: An analytical framework for immunization programs in Canada. Vaccine 2005, 23:2470-6. (Read it here)

  • Lippman A, Melnychuk R, Shimmin C, Boscoe M. Human papillomavirus, vaccines and women's health: questions and cautions. CMAJ. 2007 Aug 28;177(5):484-7. Epub 2007 Aug (Read it here)

  • Professor Allyson Pollock discusses with Newsclick the Path Human Pappilomavirus Vaccine trials in Gujarat and Andhra Pradesh  http://newsclick.in/india/paths-hpv-trials-india-troubling-questions

Additional Reading

  • Altman D. Practical statistics for medical researchers. (1991). Chapman and Hall (Buy it or check library availability)
    • Chapter 13, sections 13.1-13.3 on analysis of survival times
    • Chapter 14, section 14.4 on diagnostic tests
  • Graham JE Mishra A. Global challenges of implementing human papillomavirus vaccines International Journal for Equity in Health 2011, 10:27
    (Read it here)
  • Barrett G, Cassell JA, Peacock JL et al. National survey of British public’s views on use of identifiable medical data by the National Cancer Registry. BMJ 2006; 332: 1068–72. (Read it here)
  • Damery, S., Ryan, R., McManus, R.J., Warmington, S., Draper, H., Wilson, S. The effect of seeking consent on the representativeness of patient cohorts: Iron-deficiency anaemia and colorectal cancer Colorectal Disease ,2011;13 (11), pp. e366-e373 (Read it here)
  • Harnden A, Lehman R. New primary care series: Easily Missed? BMJ. 2009 Feb 19;338:b491. doi: 10.1136/bmj.b491. (Read it here)

WEBPAGES

Lecture Notes and Powerpoints