By Sanjay Basu, MD

In the olden days, doctors would travel from house to house when community members fell ill. Now, we usually expect patients to come to our office-based clinics. The modern model of care is certainly more efficient for us as physicians. But it’s also a barrier for patients to receive medicine; the highest-risk people usually make it to our clinics after being discharged from their first or second hospitalization, well after high blood pressure or diabetes has already taken its toll on their bodies. Our latest research suggests that we can statistically predict which people are most likely to end up having chronic diseases five or ten years from now. We can pinpoint these people right down to which house they live in. Such predictive models present a new opportunity to prevent disease before it becomes costly or deadly. In this week’s post, we look at a new idea for community-based disease prevention in medicine: the geographical mapping of chronic disease risks, and preemptive visits of healthcare workers to households where people are likely to become ill in the future.

The physician Jeffrey Brenner became famous for piloting a model of healthcare that would attempt to simultaneously improve services while reducing healthcare costs in his city of Camden, New Jersey. His model, recently profiled in Atul Gawande’s popular New Yorker article “The Hot Spotters”, was based on a simple observation: that sick people with poorly-treated diseases tend to be clustered in certain parts of the city.

The sickest areas are not always the poorest, surprisingly; some city blocks with a higher rate of poverty have lower hospitalization rates than other areas with a lower rate of poverty, probably due to several other neighborhood factors like social cohesion (no neighbors to help out when you’re sick) and lack of access to a grocery store (leaving you to purchase junk food from gas stations or liquor stores). Brenner started to make maps of his city using local hospital admissions data, trying to identify where people with the highest healthcare costs tended to live. He found “hot spots” of disease in certain nursing homes that were unsafe, or housing projects with poor access to essential nutrition needs. And he reached out to those people who were sickest, to give them special attention as a doctor: more frequent medical visits than a regular patient would get; a “health coach” to ensure they were able to get their medications and take them properly; more social workers to tackle insurance problems or to fill-out Meals on Wheels paperwork; community meetings in the worst-affected blocks, to rally for political change.

This model of “hot spotting” quickly spread to other major urban areas. As part of San Francisco’s public health system, I work in the “Housing and Urban Health” clinic, a primary care “medical home” that reaches out to patients in the Tenderloin district of the city. The clinic provides serial visits to physicians, psychiatrists and nurses for patients who receive services as far ranging as daily dressing changes for chronic wounds to the direct dispensing of medications every morning so that even the most transient people can take their pills on schedule. Case managers come knocking on patients’ doors in the high-rise “single room occupancy” hotels in the area, finding out why patients missed appointments, and even helping them to negotiate “behavioral contracts” to avoid getting evicted. And despite how extensive these services seem, there’s one striking reason that our City Council keeps them around: to save money. By getting people into substance abuse treatment and averting associated crimes and hospitalizations, and by preventing extremely expensive trips to San Francisco General Hospital’s Emergency Room for out-of-control diabetes or high blood pressure, this program and others like it around the country have averted costs for city councils with already-constrained budgets. One of my patients had previously visited the emergency room 56 times in one year (that’s more than once a week) for problems caused by alcoholism (falling down stairs, having a seizure, etc.); not only does every doctor and nurse in the ER know him by name, but they joke that he’s back in his usual “lounge chair” (the gurney), requesting his coffee cup. Since enrolling in the program, he’s only gone twice to the ER (once for pneumonia and a second time after stepping on a nail), and is no longer homeless or chronically drunk. Last week, he got a part-time job in a local restaurant.

But there is something deeply unsettling about this “hot spot” model. If we can look at the data describing ambulance pick-ups by city block, or the addresses of people who end up in the ER, or the rate of drug overdoses at different intersections, and map all of that information out in a way that helps us pinpoint where ill people need services the most, then why can’t we prevent the illnesses in the first place? Can’t we look at the data on what environments are most likely to make people sick, and prevent them from even getting disease—by ringing their doorbells and preemptively offering preventive services?

When I posed the question to a group of physicians recently, I got pummeled by doctors on both the left and the right wings of the political spectrum. The liberals were afraid that if we said that “prevention is better than cure,” we’d play into the hands of Republicans who want to cut-off healthcare from people who are already sick. Besides, prevention is too difficult, they said, because no one takes a doctor’s advice until after they’re already ill. The conservatives thought that we already spent too much money on people in the same neighborhoods, taxing those who work for a living to pay for those who have delved into drugs and fatty foods and made other bad decisions, so mass media education alone would do better than paying for yet another new welfare-style program. In any case, I was told, this was a matter of poverty and politics, not a matter of medicine.

It seems to me that all of these excuses are fairly weak . There is no reason that public health prevention programs should be mutually exclusive with providing medical care; in fact, some of our most effective prevention opportunities exist among people who already need medical care for one condition (e.g., diabetes or HIV) and for whom good medicine for that condition can avert secondary problems that cause suffering and rack-up medical expenses (e.g., kidney failure or infections, respectively).

Furthermore, models of community-based prevention do exist, and do quite well, often in the unlikeliest of places. The group Nyaya Health has been among many to pilot community health worker programs that send teams of roving nurses out to patients’ homes—often in the most inhospitably mountainous regions of Nepal. Armed with a minimal amount of medical equipment in a backpack, it’s possible to deliver prevention door-to-door, whether in the form of vaccines and medications, or health advice and assistance. And this task should be easier on the flat terrain of urban America than in the Himalayas. Such door-to-door prevention is the basis for the “active case finding” approach to tuberculosis control, which involves tracking down family members and friends of tuberculosis patients throughout both urban and rural regions, to treat latent tuberculosis before it becomes a deadly active disease. This model has been used for decades; there’s no reason now to prevent those roving agents from visiting high-risk people with a blood pressure cuff or glucometer once a week, to assist with dietary changes or adjust preventive medications or provide other support to keep them out of illness even if they wouldn’t otherwise come to the doctor’s office until they actually feel symptoms of disease in another five or ten years. What’s most surprising about these programs is that people really do open their homes to folks who act in good faith; some of our patients in the Tenderloin mention that we’re the first people in years to knock on their doors and see how they’re doing. And after entering, we discover new issues to address, like the dust content of a public housing building where future asthma sufferers live.

What about problems like drug use or obesity? Are these problems just a matter of bad decision-making, which can’t be repaired by bringing access to preventive services to someone’s home? An abundance of research suggests that the quality of a neighborhood truly matters for these problems: a recent New England Journal of Medicine study showed that when people are randomized to live in low-income housing in a low-income neighborhood, versus similar housing in a higher-income neighborhood, the latter group reduced their rates of obesity in spite of having the same socio-demographic characteristics as the former group (possibly because of easier access to grocery stores and safe parks to exercise in). The same trends appear to apply to substance abuse as well; a neighborhood’s influence on health includes the likelihood of becoming a drunk or getting addicted to drugs. But since we can’t move everyone out of poor neighborhoods into rich ones, trying to correct for the deficiencies of some neighborhoods through enhanced services—whether by simply providing cooking recipes to make healthier food with what’s locally available and inexpensive, or coming to a person’s home for weekly blood-pressure monitoring—could avert the onset of diseases that leave households with medical bills and the loss of a breadwinner after strokes and heart attacks. There’s early data from community-based prevention programs that even difficult problems like substance abuse can be averted through local, door-to-door action of this kind. Even for the hard-core right-wing folks who don’t want to pay for their community members’ medical expenses, the reality is that their communities will be increasingly blighted by neighbors who descend into sickness, and current data suggest that no amount of segregation can prevent that from affecting the overall economy, even if the white picket fence around their homes are built far away from the problems of the inner city.

The fact that our hospitals are overrun with preventable diseases makes the neighborhood factors affecting health a matter for physicians as much as it’s a matter for anyone else involved in their community. We now have the technology and data to make maps of who is likely to become ill in the future—the predictive models to know what constellation of demographic, social and economic factors are likely to substantially increase the risk of different chronic diseases. We also know, from our hospital databases, which people are unlikely to access doctors or healthcare advice or health resources before they are rushed in an ambulance to the ER a few years from now for complications of undiagnosed or uncontrolled disease. Even as we try to address those underlying factors causing these disease (like poverty and inequality), which will take decades, we have the resources and medical know-how to design good prevention interventions to avert illnesses among people who currently live under the conditions that will cause disease before we rectify the underlying vast social problems. Now, it seems, we just need the willpower to make prevention a practical reality, even if it requires making a few house calls.

Sanjay Bansu, MD, PhD, is a public health epidemiologist. His blog, EpiAnalysis, is a forum for public health epidemiologists who study global health data, healthcare policy, economics, and sociology.