At any moment, someone in the U.S. most likely is having an asthma attack. The breath-robbing disease afflicts around 25 million Americans, and every year about half of them lose control of their asthma. They may rush to the emergency room or reach for a rescue inhaler, a source of quick-acting drugs that can relax constricted airways in minutes. Predicting who is at risk of such crises is difficult, however, because the relevant statistics that would identify trends come from the patients' own recollections days or weeks after the emergency.

In several U.S. cities, a new technology may change that. In Louisville, Ky., in parts of California and in Washington State, asthma patients are using rescue inhalers topped with a small sensor that wirelessly broadcasts when, where and how often the device is used. The data pass through a secure server to patients' mobile phones and a physician's Web dashboard, providing an instant record of how well a patient is doing and archiving the information for future reference.

The device and data-monitoring system—which are collectively called Asthmapolis and which were approved by the U.S. Food and Drug Administration last July—constitute just one example of an emerging strategy in a movement so new that no one has yet coined a catchy name for it. That movement holds great promise because it combines traditional medical record keeping and public health surveillance with data mining and mobile phone technologies. Together these tools produce deep, up-to-date reports that can benefit patients and medical researchers, as well as public health and environmental authorities, all at the same time.

“If you think about the driving forces that are going to shape health care for the next 20 to 30 years, three things stand out: major aging in the population, massive growth of chronic disease, not enough caregivers,” says Steven DeMello, director of health care at the Center for Information Technology Research in the Interest of Society at the University of California, Berkeley. DeMello says that mobile diagnosis and surveillance could help blunt the impact of changing demographic trends by recognizing health crises early, by providing connections for remote care and by giving patients enough information to gain control of their disorder.

First Breath

Asthmapolis emerged from co-founder David Van Sickle's frustration with government asthma data, a feeling that burgeoned after he received his Ph.D. and while he was serving as a disease detective in the National Asthma Control Program at the Centers for Disease Control and Prevention. “Despite all that we know about asthma and how to treat it, the majority of individual patients actually have uncontrolled disease,” he says. “Their physicians can't course-correct, because patients don't report how poorly they're doing, and so they end up at higher risk of ER visits, hospitalizations, missed days of school and work—and that's all below public health's radar.”

Van Sickle realized that patients were already carrying around devices that could objectively report their status: rescue inhalers. Most asthma patients take slow-acting drugs daily to keep their condition in check; repeated use of an inhaler signals a developing emergency. Beginning in 2006, Van Sickle and several partners created a wireless sensor that is now being tested in various settings. In Louisville, for example, researchers are using the device to identify local environmental triggers of asthma; in Sacramento, the focus is on proper follow-up care.

The Louisville project's sponsor is the municipal government. Ted Smith, its director of innovation, says Louisville hopes to deploy at least 500 sensors to construct a yearlong portrait of the impact of the disease on the population and the role that the city's notably poor air quality plays in making it worse. The Sacramento project is based inside Woodland Healthcare and Mercy Medical Group, two subsidiaries of the health care system Dignity Health. The goal is to test whether patients' health is improved by real-time feedback of their symptoms to their physicians. Michael Patmas, Woodland's chief medical officer, says the project may benefit other patients as well. First, many local asthma patients are farmworkers whose dusty outdoor work provokes their attacks; better management of their health might keep them out of the ER and thus reduce overcrowding. Plus, comparing the aggregated data from the patients' sensors with local weather reports could allow the hospital to alert all patients to possible risks through, for example, short text messages (SMS). “If it's dry, and it's hot, and the wind is blowing in a certain direction, we can send an SMS warning: ‘Bad weather conditions today,'” Patmas says.

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Tracking Trends

Technologies such as Asthmapolis represent the confluence of two trends that are themselves new: the remote monitoring of patients and the collection of surveillance data from untraditional sources.

Remote monitoring tracks patients with chronic conditions, such as congestive heart failure, that might flare up into emergencies. Patients keep devices in their homes or on their person that wirelessly or electronically alert health care workers to worrying changes. The Veterans Health Administration (vha) has been experimenting with remote monitoring for over a decade. The linked devices range from glucose meters for diabetics to bathroom scales because weight changes can indicate worsening congestive heart failure. Trials outside the vha have included electrocardiographs hooked up to a home phone line to check for early signs of heart failure; daily medication dispensers that wirelessly communicate whether they have been opened; smartphone apps through which diabetics can report what they have eaten and how much insulin they have self-administered; and Bluetooth-enabled peak-flow meters, which asthma patients can use to detect whether their airways are becoming constricted.

Because most of these technologies are new, only a few comprehensive studies have been done. So far they report big increases in patients' sense of control over their illness and overall satisfaction with their care. The technology may not prove its full worth for improving health care until sensors are used by larger groups of patients.

Most of the data gathered during remote monitoring travels from one patient to that person's doctor or team, thus targeting that single person's care. In the other trend that has helped birth Asthmapolis and similar projects, the information flow is from the many to the many—that is, extracted from multiple sources of data to benefit multiple users, who can range from public health authorities to members of the general public.

Traditionally, disease-surveillance data arise from, and stay within, medicine and public health: they originate from physicians, flow through health departments and are published by government agencies. The earliest iteration of this new, crowdsourced style of surveillance was probably ProMED-mail (Program for Monitoring Emerging Diseases), an electronic mailing list run by academic volunteers that began in 1994 and now reaches about 60,000 subscribers. ProMED-mail takes contributions from a wide array of correspondents and accepts data from official sources such as governments and from unofficial ones such as news reports. A second generation of the same concept is HealthMap, founded in 2006 by a team at Boston Children's Hospital. It combines the active contributions of readers—ProMED-mail's bread and butter—with passive, automatic-intelligence processing of government data, news reports and social-media chatter in order to produce real-time maps of disease outbreaks around the world.

Both projects have demonstrated that they can identify important developments more quickly than traditional surveillance. In February 2003 ProMED-mail relayed a query that broke through the wall of silence that the People's Republic of China had constructed around the burgeoning SARS epidemic. And in April 2009 HealthMap's Web-scraping tools spotted respiratory illness reports in Mexican newspapers a couple of weeks before the CDC announced the first cases in the H1N1 flu pandemic.

Meanwhile others are working on a generation of portable devices that gather health data. Fitbit in San Francisco, for example, makes a family of wearable sensors that communicate information about sleep and exercise to a mobile app and Web dashboard. The Scout, announced in late 2012 by Scanadu in Moffett Field, Calif., has been likened to the “medical tricorder” from Star Trek because the handheld device simultaneously measures pulse, temperature and blood oxygen. The challenge for these new devices, as with the earliest remote monitors and e-mail lists, will be persuading people to use them. There, DeMello says, the latest toys have an edge. “The idea is, you have a core monitoring technology, wrapped in a product—preferably a lovely little piece of design—wrapped in a service,” he says. “You need all of those to be successful.”

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But lovely design comes at a cost. Fitbit's least expensive device, the Zip, is $59.95, and Scanadu says consumers will pay “less than $150” for Scout. If only a small slice of the population can afford the devices in the first place, then their larger promise—providing deep data on the health of large groups—may go unrealized.