” The cancer “bad luck” story confuses group and individual risk, with naive adding-up of attribution across levels “… said george davey smith
Epidemiology, epigenetics and the ‘Gloomy Prospect’: embracing randomness in population health research and practice
2011 Paper Abstract
Epidemiologists aim to identify modifiable causes of disease, this often being a prerequisite for the application of epidemiological findings in public health programmes, health service planning and clinical medicine. Despite successes in identifying causes, it is often claimed that there are missing additional causes for even reasonably well-understood conditions such as lung cancer and coronary heart disease. Several lines of evidence suggest that largely chance events, from the biographical down to the sub-cellular, contribute an important stochastic element to disease risk that is not epidemiologically tractable at the individual level. Epigenetic influences provide a fashionable contemporary explanation for such seemingly random processes. Chance events-such as a particular lifelong smoker living unharmed to 100 years-are averaged out at the group level. As a consequence population-level differences (for example, secular trends or differences between administrative areas) can be entirely explicable by causal factors that appear to account for only a small proportion of individual-level risk. In public health terms, a modifiable cause of the large majority of cases of a disease may have been identified, with a wild goose chase continuing in an attempt to discipline the random nature of the world with respect to which particular individuals will succumb. The quest for personalized medicine is a contemporary manifestation of this dream. An evolutionary explanation of why randomness exists in the development of organisms has long been articulated, in terms of offering a survival advantage in changing environments. Further, the basic notion that what is near-random at one level may be almost entirely predictable at a higher level is an emergent property of many systems, from particle physics to the social sciences. These considerations suggest that epidemiological approaches will remain fruitful as we enter the decade of the epigenome.
Sources and more information
Epidemiology, epigenetics and the ‘Gloomy Prospect’: embracing randomness in population health research and practice, Int J Epidemiol; 40(3):537-62. doi: 10.1093/ije/dyr117, PMID: 21807641, 2011 Jun.
Read the full study in Oxford Journals Int. J. Epidemiol. (2011) 40 (3): 537-562. doi: 10.1093/ije/dyr117 – by George Davey Smith including:
- Same origins, different outcomes
- Why are siblings so different?
- Why might the role of shared environment be under-estimated?
- Reasons for over-estimating or over-interpreting the non-shared environment
- The ‘gloomy prospect’ after all?
- Mechanisms of chance events: epigenetics to the rescue?
- Chance encounters: the advantages of being random
- A gloomy or a realistic prospect for epidemiology and public health?
- Lay and professional epidemiology: catching up with common sense?
- Learning to live with randomness: reaffirming the role of epidemiology in the decade of the epigenome