Dilemmas and Conundrums from Epidemiologic Research: Have We Learned the Lessons?
• Raj S. Bhopal
Professor of Public Health
Public Health Sciences Section, Division of Community Health Sciences, University of Edinburgh, Edinburgh, United Kingdom

Epidemiology: the 7 deadly sins and the 10 commandments

 

All sciences make mistakes, and epidemiology is no exception. The difference is that epidemiological errors maim and kill, and sometimes the toll can be massive. Fortunately, the saving of life and health benefits arising from epidemiology greatly outweigh the problems. The important thing is to reflect on the dilemmas and learn the lessons from our mistakes.

 

The errors in epidemiology are mostly simple in concept. I have chosen errors to illustrate how epidemiology goes wrong, and 10 “commandments” are derived to guide us to better work. These numbers are, of course, arbitrary and chosen to match the title, which chimes with our wider culture of thought on right and wrong. Phillipe Grandjean’s recent paper on the seven deadly sins of environmental epidemiology covered the human frailties of epidemiologists, so this paper focuses on the scientific discipline, rather than its practitioners.

 

The chosen seven sins are as follows:
1. Failing to provide the context and definitions of study populations.
2. Insufficient attention to evaluation of error.
3. Not demonstrating comparisons are like-for-like.
4. Either overstatement or understatement of the case for causality based on associations.
5. Not providing both absolute and relative summary measures.
6. In intervention studies not demonstrating general health benefits.
7. Failure to utilise study data to benefit health.

 

The 7 commandments arise naturally as follows:

Sin 1 commandment:
		State the location and timing of fieldwork, and describe the study population in detail, especially age, sex, socio-economic status and ethnic composition.
Sin 2 commandment:
		II Don’t pretend error does not exist. If possible measure it. If not, say so. In multi-ethnic or multi-lingual contexts, pay close attention to cross-cultural validity of all measures.
Sin 3 commandment:
		Start with detailed comparisons of subgroups – and don’t rely solely on one approach to control of confounding.
Sin 4 commandment:
		Never say this design cannot contribute to causality or, equally, imply causality is ensured by your design. Offer a judgement based on a theoretical perspective on causality and the world’s empirical and theoretical literature.
Sin 5 commandment:
		Give numbers, rates and comparative measures – rates hold primacy – and adjust summary measures, particularly odds ratios (ORs), appropriately.
Sin 6 commandment:
		Ensure general benefits (mortality/morbidity) exceed the general costs before recommending a public health or clinical application. No one is interested in substituting, for example, less heart disease for more cancer.
Sin 7 commandment:
		Epidemiology needs connections to those who apply work e.g. politicians, doctors, public health specialists. But these people need to hear a unified voice. It is time for a World Council on Epidemiology that makes recommendations on when and how epidemiological data are ready for application. Such an organisation would tackle the dilemmas and conundrums we face and ensure we learn the lessons from both our mistakes and our triumphs. The IEA should press for this Council.
		(viii) triumphs. The IEA should press for this Council.

CBE, DSc (hon), BSc, MBChB, MRCP (UK), MPH, MD, FFPHM, FRCP (Edin)
Professor Raj Bhopal was born in India and raised in Scotland, attending schools in Glasgow. He graduated from Edinburgh University in physiology (in 1975), in medicine (in 1978) and as Doctor of Medicine (in 1991). After house-jobs (internships) and general practice, he trained in Public Health Medicine in Glasgow. He was appointed lecturer at Glasgow University in 1985, senior lecturer at Newcastle University in 1988, and Professor and Head of Department of Epidemiology and Public Health at Newcastle University in 1991. He returned to Edinburgh as Alexander Bruce and John Usher Professor of Public Health in 1999. Professor Bhopal was appointed Head of the Division of Community Health Sciences 2000-2003. He was also a non-executive director of the Newcastle and North Tyneside Health Authority (1992-l996), and a non-executive Director, of the Health Education Authority ( 1996-1999). Professor Bhopal has about 150 peer reviewed publications in subjects including Legionnaires’ disease, environmental epidemiology, primary care, ethnicity and health, and the application of epidemiology. Book chapters include: Health Care Needs Assessment: Black and Minority Ethnic Groups. His textbook, Concepts of Epidemiology was published in 2002. His other books are edited collections: The epidemic of coronary heart disease in South Asian populations: causes and consequences and Public health: past, present and future. He is currently researching ethnic variations in cardiovascular disease. His textbook ‘Ethnicity, race and health in multicultural societies’ was published by OUP in January 2007.

He was honoured with the award of the CBE (Commander of the British Empire) by the Queen in 2001 and honorary DSc from Queen Margaret University College in 2006.

 

His personal interests include golf, rambling, chess and, most of all, spending time with friends and family.