Commentary: Epidemiology? Keep it broad and deep

Klim McPherson

London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.

Zielhuis and Lambertus1 are asking us to draw a boundary around epidemiology that includes only so called ‘biological’ determinants of disease. They invoke no clear justification or claim any advantage for so doing. Needless to say their argument seems to assume that biology is scientific and that the social sciences like sociology and psychology are not, and they also implicitly connect biology with medicine. This is a normal part of a sloppy argument. Public health in the UK is currently likewise professionally protected for doctors, and hence it has come to be synonymous with public health medicine. Then the illegitimate protection is self-justified and the dominant protectors of the boundaries (the BMA in this case) no longer need to justify them, except when challenged.

I believe we must resist (or simply ignore) this derivative proposal for similar reasons. Epidemiology is understanding the systematic determination of ill health by time, place and person. Firstly, it is the study of causes and determinants of disease and as such it must allow specialization within its boundaries to study, with enthusiasm, any plausible set of determinants. Secondly, most determinants interact in complicated ways, so even without specializing in social causes every epidemiologist must surely understand the rudiments of their potential effect. To exclude these experts by assigning them necessarily to another enterprise is simply stupid. To describe an epidemiologist who confronts questions from sociology as ‘merely a technician’ describes precisely why.

What, moreover, is the point of attempting to exclude parts of the complex epidemiological landscape? I believe this argument is grounded in an elitist agenda (just like UK public health medicine currently is). All such elitist agendas must have, at the very least, a clear net benefit for the purpose of epidemiology, and in this case no such benefit can be possible. The single argument proposed in favour is that ‘shopping in neighbouring scientific fields’ invites inexpert interpretation. Well not necessarily! The solution is not to ban such progress but to require appropriate knowledge to enable people to make progress. After all the ‘social’ component of human immunodeficiency virus, of coronary heart disease and of most cancers is palpable and germane, but complex. The psychological component is less obvious possibly because we have all kept it on the periphery of our concerns. We should instead be encouraging rigorous and systematic study from knowledgeable specialists to advance this understanding too. To tell the best psychologists that they have no place in the epidemiological enterprise can only be justified by evidence, and these authors have none.

These proposals are therefore just silly! Worse, they invite further disparagement and scientific neglect of important areas. For what scientific purpose I simply cannot discern from their article.

Reference

1 Zielhuis GA, Kiemeney LALM. Social epidemiology? No way.Int J Epidemiol 2001;30:43–44.[Free Full Text]