Manifesto, Project and History
Gestational Diabetes
Related Work
Old Material

Guardian Angel
Personal Lifelong Active Medical Assistant

This is a historical archive of an important project begun in 1994, but no longer running. Many of the references to outside material are outdated, and unfortunately many URLs that led to useful sites have become "dead" links. We make no attempt to fix these or to update the site with new links.

Extended Manifesto
New Scientist report
PING Overview from BMJ
PING Architecture paper
from Int. J. Med. Inf.

Guardian Angel is a collaborative project, currently between the MIT Lab for Computer Science's Clinical Decision Making Group (MEDG) and The Children's Hospital Informatics Program (CHIP), begun in 1994 to put power and responsibility for health care more into the hands of patients.  The informal arguments for this are simple:

Therefore, we should provide you the tools to collect and manage your health data, to educate you about your relevant personal and family health conditions, to help you manage your own treatment, to augment your ability to observe the effects of diseases and treatments on your body, to communicate more effectively with your health care providers and with other communities of patients, researchers, etc.

The Manifesto, the Project and History

The Guardian Angel vision is more fully explained in a technical report we call the manifesto, Guardian Angel: Patient-Centered Health Information Systems. This contains most of the text of a proposal submitted in March, 1994 to ARPA in response to BAA 94-13, for the Health Information Infrastructure Program.

Our specific proposal was to build and test comprehensive systems for patients suffering from insulin-dependent diabetes, hypertension, or undergoing anticoagulation therapy.  The project was star-crossed, as it ran into the national debate about whether ARPA should or should not play a MITI-like role in the US.  Our proposal was initially funded under ARPA's Health Information Infrastructure Project.  The funding was then delayed, however, by ARPA's internal wranglings about whether the medical foci we chose were really relevant to the needs of the military; after all, diabetics are not accepted into the services. Oddly, our program manager eventually assigned our application area to be the care of high-risk pregnancy--another condition rare among active-duty military, though common among their dependents.  We began a cooperative project to support women with gestational diabetes at Bethesda Naval Hospital.  At this time, the Congressional elections of 1994 brought a much more conservative leadership to power, ARPA was renamed DARPA (D=defense), and its director discouraged any projects that "did not go BOOM."  Our effort was scaled back and then cut off.  Our early efforts and results on the gestational diabetes problem are described below.

After early 1995, we sought support from NIH and from private health-related foundations for development of our overall vision.  Although we generally found a very favorable reception to the ideas, funding was not forthcoming (though we were encouraged by several close calls).  Mainly, reviewers were skeptical that we could achieve all our objectives with any reasonable amount of funding, and wanted empirical proof that our ideas would work before they would invest in supporting it.  Eventually, we have tried to resolve this "chicken and egg" problem by decomposing our efforts into various components that, together, will constitute the Guardian Angel.  With this strategy, we have succeeded in attracting partial funding, and are working on various components of the overall project.  The following sections describe these components.

Personal Internetworked Notary and Guardian
Indivo Health

Every other component of Guardian Angel depends on having a comprehensive life-long record of the individual's health-related information.  In our view, this records needs to have the following characteristics:

Our approach and its architectural implications are described in

Mandl, K. D., Szolovits, P., Kohane, I. S., et al. (2001). Public standards and patients' control: how to keep electronic medical records accessible but private. British Medical Journal 322(7281): 283-287.

A description of our initial architecture and implementation is

Riva A., Mandl K. D., Oh D. H., Szolovits P., Kohane I. S. (2001) The Personal Internetworked Notary and Guardian. International Journal of Medical Informatics. 62: 27-40.

Simons, W. W., Mandl, K. D, Kohane, I. S. (2004) The PING personally controlled electronic medical record system: technical architecture. Journal of the American Medical Informatics Association. 12:1:47-54.

Our colleagues at Children's Hospital Informatics Program (CHIP) have led development of this project, developed a prototype implementation originally named PING (for Personal Internetworked Notary and Guardian), and deployed a number of small pilot studies based on this technology. In 2006, that system was renamed Indivo, and in 2007 it has been adopted as the technical basis for the Dossia personally controlled health records system. Dossia was a non-profit consortium of large employers who have banded together to provide long-term health records for each of their employees, as a bet that such records will improve health care and perhaps reduce costs. The consortium consists of Applied Materials, AT&T Inc., BP America Inc., Cardinal Health, Intel Corporation, Pitney Bowes Inc., sanofi-aventis, and Wal-Mart, and covers about eight million employees. Walmart rolled out deployment of the system to its 1.4 million employees and their dependents in October 2008. It was discontinued in 2016.

The Guardian Angel project has had a significant influence on the development of personal health records, and has been acknowledged by some as the inspiration for their subsequent efforts. Among these are:

These are typically "tethered" systems, in that they rely on the underlying institutional information systems of their provider organization. Thus, unlike Indivo, they do not really give patients effective control over their records and they don't support any easy way to move records to a new location or provider. They do, at least, provide comprehensive access to all clinical data that exist in electronic form. In 2007, a number of large organizations have adopted or re-discovered the patient-conrolled model:

Since 2006, there was an annual meeting on Personally Controlled Health Record Infrastructure hosted by Harvard Medical School, which has brought together many advocates and developers of such systems.


Communication between a patient and providers is, of course, critical to health care and maintenance.  Under the leadership of Dr. Ken Mandl and in collaboration with W3Health, Inc., in 1998 we built a system that provides follow-up information and help for patients who have visited the Children's Hospital Emergency Department.  For example, (the parents of) a child who has had stitches to repair a laceration get a Web address and password that gives customized, day-by-day follow-up information for this visit.  It reminds the patient to continue taking the prescribed antibiotics, teaches how and when to change the dressing, describes and shows how the healing wound should look after various lengths of time and demonstrates conditions under which medical attention should be sought.  This content in fact changed from day to day, as different actions and concerns became appropriate during the follow-up period.  We created Web content appropriate for about two weeks of follow-up care for conditions that account for about half the ED visits.  For each patient, the ED doctor could customize the daily content, typically by adding or modifying advice about unusual conditions specific to the patient.

One of the critical factors in designing a Web-based health delivery system is the "digital divide"--impoverished access to computer and communication technology for impoverished members of society.  We have found that access does in fact vary with economic status, but we also see year-to-year improvements in access even by the hospital's poorest clients.  Anecdotally, we were pleased when a mother living in a homeless shelter was delighted to receive her access instructions, happy that she finally had some reason to try out the computer at her shelter.  The system provides all its functionality through a Web browser and uses SSL encryption, so information is encrypted in transit and no confidential information is stored on the user's machine.  This enables private communication even over public terminals such as those many find at schools, libraries, employers or shelters.  To make this possible, "email" in the system is not actually delivered as email but as messages accessible to the user when visiting their custom site.

HealthConnect is described in

Mandl, K. D., Kohane, I. S. HealthConnect: clinical grade patient-physician communication. Proc AMIA Symp 1999;(1-2)849-53.

More general doctor-patient email communications and related social equity issues are discussed in

Mandl, K. D., Katz, S. B., Kohane, I. S. Social equity and access to the World Wide Web and E-mail: implications for design and implementation of medical applications. Proc AMIA Symp 1998:215-9.

Mandl, K. D., Kohane, I. S., Brandt, A. M. Electronic patient-physician communication: problems and promise. Ann Intern Med 1998;129(6):495-500.

Mandl, K. D., Feit, S., Pena, B. M. G., Kohane, I. S. Growth and determinants of access in patient e-mail and Internet use. Arch Pediatr Adolesc Med 2000;154:508-11.

W3-EMRS: World Wide Web based Electronic Medical Record System

W3-EMRS is a virtual medical record that can be assembled from data about a patient held in various forms by a number of different institutions.  Our initial foray into medical record systems architecture and development began in 1994, at about the same time as our initial work on Guardian Angel.  We had observed that many institutions were collecting more and more clinical data about patients, but each in its often unique, proprietary, historically-developed, incompatible forms.  Inspired by the rocketing success of the early World Wide Web, we believed that the records sharing part of the Guardian Angel vision could be solved by using the same kinds of methods as the Web to provide a seamless virtual shared record that any patient (or any provider caring for the patient) could assemble on-the-fly from whatever institutional systems held those records.  To accomplish this, we used four architectural principles:

  1. Deal only with a modest subset of all possible records, so that most source systems would be likely to contain and support them.  Our initial demonstrations systems included the following:
  2. Assemble and display data as needed, and do not create a permanent centralized repository of clinical information about patients.  We felt that issues of data confidentiality, proprietary interests, and a history of political opposition to "national medical databases" required this distributed, ephemeral treatment of data.
  3. Use a common communication standard for representing and communicating clinical content.  We adopted HL7 whenever it proved comprehensive and unambiguous, and several extensions where it was (at that time) inadequate.  Because most existing systems did not provide HL7 as an output option, we developed customized site servers for each source site that could translate our queries into local retrieval operations on the information system and could then encode the responses into HL7 for use by other components of our system.
  4. Use Web Consortium (W3C) standards to leverage rapid development and deployment of advanced technologies, mostly driven by non-health uses.  For example, our user interface is a Web browser, we rely on communication security provided by SSL, and we adopt the stateless communication model popularized by the Web.

These choices made our implementation efforts enormously easier than that experienced by earlier projects, and freed us from problems of software distribution and installation, the need for sophisticated client computers, etc.  The references describe the architecture, implementation choices, policy development for controlling the privacy of information to be shared, extensions of the architecture to real-time monitoring scenarios, etc.

Ultimately, this architecture was successfully adopted by several projects that operate internally to a single controlling institution.  Despite having built a working prototype of a system to share clinical data among Boston-area emergency departments, however, we found institutional suspicion and resistance impossible to overcome, because no institution wanted to give access to its patients' records to other, competing institutions.  This observation has led us to our current PING concept: all institutions owe access to data to the patient, so if the patient effectively controls the data, it cannot be denied by anyone else to providers the patient selects.

Kohane, I. S., Greenspun, P., Fackler, J., et al. (1996). Building National Electronic Medical Record Systems via the World Wide Web. J Am Med Inform Assoc 3(3): 191-207.

Kohane, I. S., van Wingerde, F. J., Fackler, J. C., et al. (1996). Sharing electronic medical records across multiple heterogeneous and competing institutions. Proc AMIA Annu Fall Symp: 608-12.

van Wingerde, F. J., Schindler, J., Kilbridge, P., et al. (1996). Using HL7 and the World Wide Web for unifying patient data from remote databases. Proc AMIA Annu Fall Symp: 643-7.

Wang, K., van Wingerde, F. J., Bradshaw, K., et al. (1997). A Java-based multi-institutional medical information retrieval system. Proc AMIA Annu Fall Symp: 538-42.

Fraser, H. S. F., Kohane, I. S. and Long, W. J. (1997). Using the technology of the world wide web to manage clinical information. BMJ 314(7094): 1600-.

Rind, D. M., Kohane, I. S., Szolovits, P., et al. (1997). Maintaining the Confidentiality of Medical Records Shared over the Internet and the World Wide Web. Ann Intern Med 1997(127): 138-141.

Halamka, J. D., Szolovits, P., Rind, D. and Safran, C. (1997). A WWW implementation of national recommendations for protecting electronic health information. J Am Med Inform Assoc 4(6): 458-64.

More details on this project, are still on-line, though unfortunately a machine failure makes the demonstration database no longer accessible.

The Gestational Diabetes Prototype

Our initial ARPA-funded effort, in 1994-5, was to develop a suite of tools for use by women with gestational diabetes being cared for at the Bethesda Naval Hospital.  Gestational diabetes is a condition that sometimes develops during pregnancy, and usually clears up after delivery.  Treatment is aimed toward limiting the patient's hyperglycemia (high blood sugar) by diet or drug treatment.  The objective is both to protect the mother's health and to prevent two dangerous conditions for the baby: an abnormal increase in the amount of amniotic fluid that can induce early labor, and the baby's overproduction of insulin to process extra sugar from the mother, which can lead to a rebound effect where the newborn becomes hypoglycemic after birth.

We planned to build two major components, one to be used by the mother, the other for the clinic.  The home system was to support the following:

The clinic system was to provide the following:

Although we built many parts of the home system, the project ended before the clinic system could be built and before the entire system could be integrated and deployed.  As a result, no publications resulted.  Nevertheless, internal notes are available that discuss some of the design issues and show at least static images of parts of what got built.

Related Work

Patient-centered medical care has been a hot topic in medical computing circles for a number of years.  The annual meeting of AMIA in 1993, for example, was subtitled "Patient Centered Computing."  Alas, much of this focus is more hype than reality.  For example, one innovation claimed by a presenter at that meeting was to recognize that data about a single patient from different departmental systems at a hospital should all be accessible together.  This is certainly a useful and long-overdue capability, but "patient-centered" in only the weakest sense.  Below, we mention a few of the efforts we know that come closer to the spirit.  We do not here attempt to survey the field.

Several companies have been early to create systems that allow a patient to store and retrieve personal health records on a Web server.  For example, the initial record system created by VitalWorks gave patients a convenient way to record information about their health, doctor's visits, medications, etc.  The difficulty in most such systems, including theirs, is that all information must be put into the system by hand, and there are no facilities to deliver these data in any systematic way to providers.  VitalWorks' business model apparently changed, and as of 2007 seem no longer to be operating. Other companies that support collection of patient data now also often couple this activity with some other use of the data.  For example, Doctor Global enables a patient-contributed health record in order to support remote consultations (or second opinions) by their medical staff. Most similar efforts known to us have also suffered from the closed, proprietary nature of their record systems, including such well-known ones as WebMD, which at one time also offered a personal health record but today mainly supplied generic medical information.  There is no easy way to extract data entered into one of these for subsequent use in a different system, and the facilities and motivations to enter data seemed not to be enough to get the systems used.  Our Boston colleagues Schoenberg and Safran proposed a Web-based record keeping system architecturally similar to PING.

Integrating record keeping with other aspects of the ongoing activities of health care is a more difficult challenge, and is required to achieve the goals of Guardian Angel.  A few projects that more closely approximate these goals have incorporated many of its patient education and communication functions, typically focused on specific diseases.  An early effort at IBM Research developed educational laser disks and a home computer system to educate and support parents of leukemic children in administering their therapy at home.  Some systems have focused on patient (or caretaker) communications for mutual support and education.  For example, Brennan's system in Cleveland supported a community of caregivers for Alzheimer's patients.  Our Boston colleagues' Baby CareLink system provided visual communication between a hospitalized baby and his or her parents, and educational material to prepare the parents for later home care (Gray, J. E., Safran, C., Davis, R. B., et al. (2000). Baby CareLink: using the internet and telemedicine to improve care for high-risk infants. Pediatrics 106(6): 1318-24.).  An interesting but incomplete system at Pittsburgh supported patients who had questions about their neurological condition (Buchanan, B. G., Carenini, G., Mittal, V. O. and Moore, J. D. (1998). Designing computer-based frameworks that facilitate doctor-patient collaboration. Artif Intell Med 12(2): 169-91.).

Note: This section is quite incomplete and out of date.  Caveat emptor!

The material below is from Jon Doyle's construction of the "old" (1990's) GA page, and undoubtedly contains useful material that should be incorporated or linked to the new version, but thus far are just presented as they were.

--Peter Szolovits, Feb. 1, 2001
Slightly updated Sep. 30, 2016

The Guardian Angel Consortium
MIT, Tufts NEMC, Childrens Hospital (Boston)


What's New!
Manifesto Project Status
People Publications Other links
Patient Education Materials
Internal Information (MIT sites only)

Current health information systems are built for the convenience of health care providers and consequently yield fragmented patient records in which medically relevant lifelong information is sometimes incomplete, incorrect, or inaccessible. We are constructing information systems centered on the individual patient instead of the provider, in which a set of guardian angel (GA) software agents integrates all health-related concerns, including medically-relevant legal and financial information, about an individual (its subject). This personal system will help track, manage, and interpret the subject's health history, and offer advice to both patient and provider. Minimally, the system will maintain comprehensive, cumulative, correct, and coherent medical records, accessible in a timely manner as the subject moves through life, work assignments, and health care providers. Each GA is an active process that performs several important functions: it collects patient data; it checks, interprets, and explains to the subject medically-relevant facts and plans; it adapts its advice based on the subject's prior experiences and stated preferences; it performs sanity checks on both medical efficacy and cost-effectiveness of diagnostic conclusions and therapeutic plans; it monitors progress; it interfaces to software agents of providers, insurers, etc.; and it helps educate, encourage, and inform the patient. All this serves to improve the quality of medical decision-making, increase patient compliance, and minimize iatrogenic disease and medical errors.

For more information, write to

Last modified: 10/1/2008
Fern DeOliveira

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