The preventive paradox

Should we sacrifice individual freedom for the benefit of the population health? Or should we simply help those who really need it? These are questions that health authorities in all countries struggle with. Frequently, these questions are treated exclusively as political and ideological questions of individual freedom, or paternalism.

The purpose of this article is to inform that there is often a clear answer to what the superior approach is, if the ultimate goal is to reduce the incidence of disease. This article will try to explain why the number of sick people is most efficiently reduced by interventions which are aimed towards the entire population, rather than to those who are at the highest risk.

Alcoholic The preventive ParadoxFew people disagree that we should help severely overweight individuals in losing weight, or that we should help people with alcoholism to reduce their drinking. However, in many countries, there is substantial political and popular resistance when it comes to increasing prices or reducing the availability of alcohol or unhealthy food and drinks for the entire population. Similarly, subsidization of healthy foods is also considered politically controversial. Commonly, such universal interventions are considered paternalistic and bothersome to the large portion of the population who are in good health, and who can take care of themselves.

The expression of “the preventive paradox” was coined by Geoffrey Rose a part of an effort to try to explaining why it is possible to prevent more cases of disease and death with structural preventive efforts which are aimed at the entire population, rather than just at the high risk groups [1]. This has been considered a paradox, because large scale structural interventions frequently are viewed as having only very small benefits to each individual. In contrast, there is an obvious and important benefit in helping overweight people to lose weight, or in helping alcoholics to reduce their drinking

It is my conviction that the political discussions of how to prevent disease, would benefit greatly if the preventive paradox was widely known among politicians and among the wider population. Here follows the two basic premises which are key to understanding the preventive paradox.

  1. The risk for developing disease does not dramatically change between each level of the risk factors

This means that there is no magic point where people go from having little or no risk, to having very high risk for becoming sick. In other words, the risk of disease typically change only slightly as the risk factors change. Examples could be that the risk of diabetes or coronary heart disease is reduced slightly when individuals become slightly more physically active [2]. It is therefore unlikely that there is a sudden and large change in risk for people who go from being marginally under recommendations for physical activity, to marginally over the recommendations for physical activity. Similarly, the risk of hypertension increases gradually with increasing alcohol consumption. Again, now there is no sudden change in risk when increasing consumption to one unit of alcohol over the recommendations [3]. Finally, for BMI, there is a gradual change in risk for death (from any cause) which increases as BMI gets higher [4].

This means that all people have some risk of disease and death, healthy individuals have a relatively low risk, and people who lead very unhealthy lives have a relatively higher risk of disease and death.

  1. There are usually more people with low risk, compared to the number of people with high risk

Overeating unhealthy food the preventive paradoxFor most risk factors such as BMI, blood pressure, levels of physical activity, and alcohol consumption there are far people with low levels of risk (normal BMI, normal blood pressure, moderately physically active, and with moderate levels of alcohol consumption), than there are individuals within the high risk groups.

The combination of the gradual change in risk and the fact that the majority of people are at low risk, leads to the frequent finding that most cases of disease arise from individuals who are at low risk. Determining the number who are likely to get sick, or die is a relatively simple exercise as one can multiply the risk (typically reported in expected cases pr 1000 people), with the number of people at that particular risk level.

Examples of the preventive paradox

I will here describe some real life examples of the preventive paradox. The first example deals with injuries and alcohol consumption where an American study found that most alcohol-related harm and injuries occurs among individuals who are not alcoholic and have alcohol consumption habits which are considered normal and not harmful  [5].

A second example of the prevention paradox refers to the increasing risk of giving birth to children with Downs syndrome among older mothers. While the risk indeed is much higher among women over 40 years of age, only 13% of children with downs are born from mothers over 40, and 51% of children with downs syndrome are born from mothers under the age of 30, who have the lowest risk [1].

Finally, although individuals who are overweight and who do not exercise, are at relatively higher risks of dying from coronary heart disease, there are far more deaths from this disease among individuals who are not overweight and who have led a life with normal healthy levels of physical activity. Indeed coronary heart disease is the leading cause of death for all men from western countries [1].

Structural interventions covering entire populations are possible, and efficient

Interventions aimed at the entire population may be difficult to initiate and may also be very unpopular among large groups of the populations. For example, the ban on smoking in bars and cafes in Norway in 2004 along with the heavy taxation on tobacco, was been very unpopular among large sections of the population. It reduced the convenience and possibility of enjoying cigarettes in social settings, as well as increased the prices. This was my many considered as a paternalistic policy and an overreach by the national health authorities. However, the results from these policies are looking quite promising in its potential to reduce the total number of smoking related diseases and deaths in the Norwegian population. An important result is the reduction in the smoking prevalence among young people as it has been reduced from 23% in 2006 to 3% in 2018. These are very positive results compared to the development in Denmark where cigarettes are substantially cheaper, more easily available, and many bars allow smoking indoors. Here the smoking prevalence among young people has also decreased over this time period, but there are still about 16% of Danish young people that smoke (down from 27% in 2006) [6]

Less controversial is the public subsidization of smoking cessation courses to smokers (a high-risk group). This is clearly a worthwhile effort which also is likely to reduce the number of new cases of lung cancer, but it does not have the potential to influence the recruitment of new smokers.

What could and what should be done

There are a number of interventions which could have great potential in reducing the number of cases of disease and death by making healthy foods and lifestyles affordable and attractive for everyone. This could include subsidization of healthy products, or building attractive and free areas for physical activity. Also, there is a great potential in introducing interventions which limit the availability and convenience of purchasing or consuming unhealthy foods, drinks, and tobacco.

Despite the apparent logic in providing structural interventions, there are a number of potential complications which need to be considered before implementing these. A few of these include the risk that taxation of tobacco or alcohol may increase smuggling and illegal markets, or the complications in determining fair and reasonable guidelines for which products to subsidize and not. Finally, there is also the political and philosophical question of the extent to which numbers of expected sick and dead should be the ultimate goal for the welfare state.

Please note that the research results presented in this paper are somewhat simplified in order to reach a broad audience. Please read the original publications if you are interested in a more comprehensive understanding of the preventive paradox.

  1. Rose G: Sick individuals and sick populationsInternational Journal of Epidemiology 2001, 30(3):427-432.
  2. Sattelmair J, Pertman J, Ding EL, Kohl III HW, Haskell W, Lee I-M: Dose response between physical activity and risk of coronary heart disease: a meta-analysisCirculation 2011, 124(7):789-795.
  3. Taylor B, Irving HM, Baliunas D, Roerecke M, Patra J, Mohapatra S, Rehm J: Alcohol and hypertension: gender differences in dose–response relationships determined through systematic review and meta‐analysisAddiction 2009, 104(12):1981-1990.
  4. Aune D, Sen A, Prasad M, Norat T, Janszky I, Tonstad S, Romundstad P, Vatten LJ: BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participantsBmj 2016, 353:i2156.
  5. Spurling MC, Vinson DC: Alcohol-related injuries: evidence for the prevention paradoxAnn Fam Med 2005, 3(1):47-52.
  6. Norge viser vejen til færre unge rygere