Personalizing healthcare: from genetics through payment to improving care?
Authors: A E Finlayson, B Godman, K Paterson, E Aston, A Haycox, Ll Gustafsson, R Ali
Journal: Journal of the Royal Society of Medicine (2013)

Interindividual variability in patients' responses to medicines, including the likelihood of toxicity, is commonly due to differences in their genetics.1 Both problems present adverse care and resource issues, with non-response rates as high as 30–60%.2 Resource issues include the cost of adverse reactions which increase the number of emergency hospital admission at an estimated cost of GB£2 billion per annum.3 Such resource issues are an increasing concern among health authorities with pharmaceutical expenditure growing faster than other components of ambulatory care, driven by ageing populations, rising patient expectations and the continued launch of new expensive drugs.4 New premium-priced medicines are being launched at over US$300,000 per year, often with only limited health gain versus current standards.4,5

Targeting valuable resources through personalization is empirically an attractive proposition for health authorities or health insurers as it reduces the numbers needed to treat (NNT) and increases the numbers needed to harm (NNH), thereby improving the health gain for patients within available resources. It claims to deliver the right treatment to the right patient at the right time.6 However, there are barriers that need to be addressed before personalized medicine becomes a reality. This article aims to stimulate this ongoing debate and provide guidance for the future.

Personalized medicine is not new. For instance, GPs in the UK do not prescribe non-steroidal antiinflammatory drugs (NSAIDs) to patients with asthma as a matter of course. The guidelines for antihypertensives are predicated on knowledge of a patient's race, age and co-morbidities. When there are a few examples, physicians can memorize and integrate these into routine practice. However, as we dissect diseases beyond such phenotypic stratification, we find increasing examples of genetic differences in therapeutic responses, some of which are already being exploited.1,7–9 This is resulting in a more heterogeneous spectrum of disease referred to by the recently coined ‘precision medicine’.6 Ultimately, full personalization of medicines will require a better understanding of the systems of genetic pathways rather than just single gene association, as demonstrated by the disappointing predictive yield of genome-wide association studies (GWAS). New technologies for whole genome sequencing and new approaches for combining information from a panel of biological variables will have a profound impact on the way in which drugs and diagnostic tests are being and will be developed, as well as the way physicians will practise medicine in the future.2

As this field of systems biology evolves with greater clinical utility in personalizing therapy, the funding and policy environment must also evolve to facilitate the expediency with such therapies that are introduced, used and evaluated in routine care.2 Currently, there are only relatively few clinical examples of personalized medicine being integrated into routine care, a phenomenon that has not been helped by the current controversies surrounding the testing of patients prescribed clopidogrel or warfarin.7–9 However, this is changing with recent research suggesting that 50% of the variability in the dosing of anticoagulant therapy can be explained by genetic factors.10 Overall, greater integration of personalized medicine into routine care will require new clinical trial structures, and innovative funding strategies that make it easier to fund new diagnostic drugs and any additional facilities along with potentially ‘valued’ drug therapy. Patient education will also be needed as the range of therapeutic options increases and becomes more complicated to navigate.