Monday, April 04, 2011

The Prevention Paradox: an Argument for the Use of Individual-Centered Approaches for the Promotion of Healthy Body Weights

When a country is bombarded by multiple disease epidemics, the question of resource allocation is essential. Many people in public health first seek a population-level approach such as banning soda machines in schools. These large-scale interventions have been shown to shift the population towards a healthier mean (Puska, 2002). In spite of this, obesity manifests itself in a population in a complex and stochastic manner that often pits the food industry against public health and the health of individuals. For this case in particular, we need to take a two-pronged strategy, combining population approaches at individual-level interventions. One group doing this is the Centre for Healthy Weights - BC, a prototype clinic and provincial resource centre based at BC Children’s Hospital in Vancouver (2011).

The population approach to behaviour change was the brainchild of Geoffrey Rose, based on his research in Kenya, where he noticed that the population-mean blood pressure of Kenyan men was lower than men in England (Rose, 1985). This observation led him to use epidemiology for diagnosing a population instead of an individual. This produced a plethora of population-level interventions such as seat belt use and tobacco control measures.

Ever since Rose, public health has touted interventions at the population level as the most effective both in terms of cost and impact (Gaziano et al., 2007). We often forget that he also wrote about the weaknesses of population-level prevention. He explained that the “prevention paradox” leads to poor motivation for an individual to change his or her behaviour, and this in turn affects physician motivation (Rose, 1985). The prevention paradox explains how behaviours that are statistically risky at a population level might not actually result in an individual developing the disease. We all know the proverbial 90-year-old who smoked a pack of cigarettes a day, ate junk food, and is a better bowler than their younger teammates. The fact is that statistics cannot make predictions at the individual level. So in conjunction with a population approach we need to work with individuals to create positive lifestyle changes, particularly those people with a propensity towards visceral adiposity. Geoffrey Rose called this approach of using “interventions that are appropriate to the particular individuals advised to take them” a “high-risk” strategy (p. 35,1985).

This is why targeting at-risk children for lifestyle change, like the method used by the Centre for Healthy Weights - BC, is one way to expand beyond a population approach. The centre doesn’t use a one-size-fits-all strategy because obesity is a complex epidemic, manifesting itself differently in each individual. Thus it also calls for a contextualized approach, which customizes behaviour change according to an individual’s needs. This helps families navigate through the complex minefield of risk factors created by technologized societies. By delivering health education based on the strengths and weakness of the particular family, the customized health education approach helps each family learn how to make sustainable healthy choices. For example, if a family that has good eating but poor exercise habits gets referred to the centre, the interdisciplinary team will work with the family to overcome obstacles to integrating physical activity into their lives while supporting and acknowledging the family’s strengths.

Although a contextualized approach would not be cost-effective for the whole population, we must remember that Rose himself, in his classic paper “Sick Individuals and Sick Populations”, called for using a high-risk strategy and a population strategy side by side (1985). In fighting a complex problem like obesity, the question of cost-effectiveness might not be the right question. On the one-hand, the CHW might not appear to be cost-effective, but considering how healthy options are thwarted by so many factors in this consumer-driven society, we need to embrace behavior change at the individual level while working at the population level to make the healthy choices easier.


Centre for Healthy Weights – BC (2011). Services. Retrieved on March 12, 2011 from

Puska, P. (2002). Successful prevention of non-communicable disease: 25 year experiences with North Karelia Project in Finland. Public Health Medicine, 4(1):5-7.

Gaziano, T.A., Galea, G., Reddy, K.S. (2007). Scaling up interventions for chronic disease prevention: the evidence. Lancet, 370:1939-146.

Rose G. (1985). Sick individuals and sick populations. International
Journal of Epidemiology, 14: 32–38.

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