6 March 2015
Advances in genomic science and trends towards patient-centred practice are paving the way for the practice of personalised medicine. Recent discourse has also emphasised the importance of disease prevention and the need to shift resources and priorities from clinical to public health practice. Preventing disease, rather than just diagnosing and treating it, is acknowledged as important. However, prevention is not synonymous with public health practice. Effective prevention of disease must now embrace classical public health, health promotion and personalised approaches that are focused on the individual and tailored to individual needs. A new approach that acknowledges this differentiation will be required if we are to reap the benefits of 21st century science for human health.
Classical public health
Public health, at least in the UK, can be best thought of as state medicine; a set of activities undertaken by government and its agents to promote health and prevent disease. Our Victorian forefathers epitomised the classic approach, as they sought to improve the health of their citizens by ensuring that they were provided with proper sanitation, clean water and reasonable housing. Legislation was a prime tool with government acting on the external and social environment. In more recent years, legislation to ensure clean air, the compulsory use of seat belts, and the prohibition of smoking in public places were further examples of this approach. Essentially this type of intervention, which normally needs to be undertaken by government, is directed to the environment as a whole, with potential for any member of the population to benefit. The citizen is not explicitly and directly targeted and (except through their compliance with the law) is not the mechanism through which the disease preventing intervention would have effect.
The evolution of public health
In the second half of the 20th century, public health began to embrace the second approach broadly termed health promotion, where programmes were established to deal with the more proximate determinants of disease. Health promotion, by contrast with classic public health interventions, sought to encourage individuals to change their behaviour: to eat more healthily, to drink less, to refrain from drugs or high risk sexual activity, and to take more exercise. Under this paradigm, the individual citizen was intentionally and explicitly targeted as the agent of the intervention, the means by which improvements in health would be effected. A successful health promotion programme necessitated the demonstration of behaviour change.
A new paradigm for disease prevention
Both classical public health and health promotion provide the foundations of a further leap forward for prevention; the personalisation of risk assessment and interventions for the individual, so called personalised prevention. This is a new paradigm for disease prevention that we wish to promote. Like health promotion it is effected through human agency, but unlike the undifferentiated messages typical of health promotion, personalised prevention takes into account individual susceptibility to disease risk (which has a biological basis), individual values and concepts of utility (which are social and culturally determined) and the need for individual autonomous decision making about the take-up of preventive interventions. The interventions that it offers require an individualised risk assessment and the provision of advice or preventive management as an interaction between the individual and some form of health professional, classically recognised as a clinical activity.
Risk assessments are likely to include some combination of clinical and family history, a range of biomarkers and imaging for risk or early disease, and increasingly the use of biosensors. Interventions may range from intensive weight reduction based on individual assessment of eating habits, to the recommendation of devices and mobile apps or prescription of pharmacological agents for chemoprevention. Finally, unlike Geoffrey Rose’s distinction between the use of population and high risk strategies in prevention, personalised prevention does not only target high risk individuals. It may equally be directed at those at lower risk who may or may not require further intervention. Properly advised, these people will experience less inconvenience and even harm from unnecessary interventions. There will also be the potential for reduced cost or more efficient use of preventive services.
Classical public health, health promotion and the new field of personalised prevention will all be important activities in the future but there is a question about how they will best be practised. The first two would seem logically to remain with public health professionals and the local authorities to which they have recently been relocated. However, the personal interaction, clinical testing and sometimes medical interventions required for personalised prevention would not sit comfortably within this structure, which does not deal with individual patients, nor would it be within the skill set of most current public health practitioners.
Reaping the benefits of the genomic revolution
We therefore pose the question – through what mechanisms will we, as a society, aim to reap the benefits that genomic medicine offers through personalised prevention? Will this be through a concerted attempt to build prevention into the training and practice of clinicians in every specialty and in primary care, or possibly by developing a new class of health professional specifically dedicated to this role? Could it become an extension of the current role of public health practitioners? We invite a wide ranging debate about how best to achieve these benefits, one which, in the UK, should involve at the very least (but not be confined to) the Royal College of Physicians, the Royal College of General Practitioners, the Faculty of Public Health and Academy of Medical Sciences. Such organisational questions need to be addressed to ensure the potential benefits of personalised prevention are available to all rather than becoming an extension of the retinue of personal trainers, counsellors and life coaches for the rich with predictable exacerbation of health inequalities.
During recent decades we have achieved many advances in basic and clinical sciences, overcoming the most complex scientific, intellectual and technological hurdles. We now understand much more about determinants of diseases and how they can be prevented. The questions that we pose for personalised prevention must now be addressed urgently if, as a society, we are to avoid once again being defeated by the complexity and inertia of implementation.