Tuesday, September 1, 2015

Why precision medicine threatens population health

Scientific guidelines produced by the American Heart Association tend to spill lots of ink on recommending complex and/or expensive tests, drugs, and procedures for patients who already have heart problems. Even when the topic is ostensibly cardiovascular prevention, as in the current AHA-endorsed cholesterol management guideline, the end result may be prescribing statins to many millions (or even billions) of additional adults. So it was a pleasant surprise to me earlier this summer when the AHA released the insightful consensus statement "Social Determinants of Risk and Outcomes for Cardiovascular Disease." In the introduction, the authors wrote:

There is increasing awareness that the benefits of advances in prevention and treatment [of cardiovascular disease] have not been shared equally across economic, racial, and ethnic groups in the United States. Overall population health cannot improve if parts of the population do not benefit from improvements in prevention and treatment. ... The premise underlying this scientific statement is that, at present, the most significant opportunities for reducing death and disability from CVD in the United States lie with addressing the social determinants of cardiovascular outcomes.

In other words, addressing social determinants of health and health disparities across the U.S. - population health interventions - are likely to have far greater benefits than providing any conceivable number of individual cardiac stress tests, cholesterol-reducing drugs, or coronary artery stents. Bravo to the AHA for acknowledging a reality that may unsettle many of its members whose incomes depend on the latter! Unfortunately, we know much less than we need to about measuring and changing social determinants of health. But the simplicity of focusing on traditional cardiac risk factors rather than nebulous concepts such as "socioeconomic position" may be leading physicians down the wrong path, as David Loxterkamp observed in a 2013 BMJ essay:

A patient recently slumped into my office clutching a paper from his employer. On it were empty boxes for me to enter blood pressure, weight, waistline circumference, cholesterol, and fasting blood sugar readings. We reviewed recent results. Only his glucose level was slightly raised, so we spent the majority of our 20 minutes talking about diet, exercise, and targets for weight loss. None of this concerned him, he revealed on his way out the door, as much as the tension in his marriage and the difficulties he and his wife were having with their autistic son.

Dr. Loxtercamp went on to argue that the primary care clinician's central role is "facilitating change," not only positive changes such as smoking cessation and healthy lifestyles, but also coming to terms with adverse changes such as divorces, illness and deaths of friends or family members, or other traumatic life experiences.

What they [patients] need from us is reassurance, commonsense advice, coordination of community resources, and knowledge of their family values. This was once our vital function, but no longer. We are on a merry-go-round, too, and now see a greater value in access and efficiency than continuity of care. ... Patients are not (only) data fields for the doctor to harvest, objects to be imaged, or problems to be solved. They are also our neighbors asking for help, using posture, gait, gesture, and facial expression to indicate where and how to proceed. Let’s first acknowledge them beneath their symptom complex and accept the story of their illness in their own words.

An obsessive focus on measurement is not the only or even the foremost threat to medicine's role in improving population health. In a recent NEJM commentary, Ronald Bayer and Sandro Galea expressed concern that the Precision Medicine Initiative may prove to be a damaging and costly distraction from the most burdensome U.S. health problems:

“What is needed now” is quite different ... if one is concerned about why the United States has sunk to the bottom of the list of comparable countries in terms of disease experience and life expectancy, or if one is troubled by the steep social gradient that characterizes who becomes sick and who dies. The burgeoning precision-medicine agenda is largely silent on these issues, focusing instead on detecting and curing disease at the individual level. ... The challenge we face to improve population health does not involve the frontiers of science and molecular biology. It entails development of the vision and willingness to address certain persistent social realities, and it requires an unstinting focus on the factors that matter most to the production of population health.

I think their concern is justified. Population health interventions may never prove to be as sexy as precision medicine. Even outstanding narratives about the statistical basis of health policy can't captivate human interest as powerfully as the girl in the well. That doesn't mean that our public investments in health should not or cannot be prioritized by what will provide the most good for the greatest number of people.