Neil Pearce on Malaise in Latter-day Epidemiology

Neil Pearce from Massey University in Australia, along with John McKinley, dissect the malaise of latter-day epidemiology in this year 2000 statement made at the retirement celebration for Ian Prior in Wellington, New Zealand:

The development of modern epidemiology includes a practical and theoretical emphasis on epidemiology as a branch of biological and clinical science; a related emphasis on studying single biologically defined risk factors; the enthusiastic use of new techniques for measuring such risk factors; a search for universal dose-response relationships; and an emphasis on the randomized clinical trial as the paradigm to which all epidemiological studies should aspire.

This modern approach to epidemiology has been increasingly challenged in recent years.

For example, John McKinley . . argues that what is now regarded as ‘established epidemiology’ is characterized by biophysiologic reductionism, absorption by biomedicine, a lack of real theory about disease causation, dichotomous thinking about disease (i.e., everyone is either healthy or sick), a maze of risk factors, confusion about spatial associations with causality, dogmatism about which study designs are acceptable, and excessive repetition of studies.

He argues that this approach diverts limited resources, blames the victim, produces a lifestyle approach to social policy, decontextualizes risk behaviors, seldom assesses a relative contribution of non-modifiable genetic factors and modifiable social and behavioral factors, and produces interventions that can be harmful. These trends are particularly noticeable with the recent rise of molecular epidemiology and especially in the renewed emphasis on issues of individual susceptibility.

Thus, in recent years has been a move to ‘go back to the future’ and rediscover the population perspective in epidemiology. For example, Geoffrey Rose has noted that entire populations may be exposed to a particular risk factor and there is usually a continuum of disease risk (rather than a clear distinction between the sick and the healthy) across populations. Small improvements in the health of a sick population may be more effective than attempts to treat illness in sick individuals. In fact, there are some situations in which ecological studies are not only necessary, but are also more appropriate, even when individual information is also available.

It is this recognition of the population context which is a key feature of the developing global epidemiology, also referred to [by Mervyn Susser] as “eco-epidemiology.”

Evidence-based epidemiology

Finally a decision as to what is appropriate to technology should be based on evidence. This is less obvious than it seems, since many epidemiological methods are not evidence-based. For example, the current wave of enthusiasm for ‘molecular epidemiology’ has led to the widespread use of biomarkers of exposure, even when there is very little evidence of their validity.

More generally, the randomized clinical trial may be an appropriate paradigm in many epidemiological studies with special risk factors, but will often be inappropriate in studies which require consideration of the historical and social contexts. As attention moves ‘upstream to the population level,’ modern epidemiological methods will become increasingly inappropriate, and new methods will need to be developed. There is nothing particularly unusual in this; all sciences develop new methods in response to new problems. The need for an evidence-based epidemiology also applies to the general ‘research strategy that is employed by epidemiologists, as well as the specific research methods that are employed, since there is good historical evidence of the value of a population-based approach [e.g. The Tokelau Islands Migrant Study; the Seven Countries Study]. (Henry Blackburn)

Resource

The Health of Pacific Societies: Ian Prior’s Life and Work. 2001. Wellington, NZ: Steele Roberts Ltd.