Blockchains are decentralized internet-based ledgers based upon Merkle trees [1] that first came to recognition and use after the 2008 whitepaper by the pseudonymous Satoshi Nakamoto [2].

This whitepaper described what was to become the first functioning decentralized digital currency named Bitcoin [3], the proof-of-concept source code of which was then released in 2009[4]. Over the intervening nine years, Bitcoin has continued its rapid development, demonstrated continued growth and recognized financial value, and created an industry of imitators which has sought to build upon the foundation Bitcoin formed.

The concept and technology behind the blockchain is the heart of Bitcoin and its numerous derivatives. As of July of this year, lists 1707 digital currencies which combine to form more than $284 billion in market capitalization [figure 1,].

One of the significant allures behind the blockchain is that its distributed and cryptographically secure nature acts as a so-called “source of truth”. Once the network achieves agreement or “consensus” to incorporate data into the blockchain, the data cannot be modified or erased. Indeed, as more and more data is sequentially added to a blockchain, data added earlier becomes more and more securely fixed, much as a tree’s later branches depend upon more proximal branches and, ultimately, the trunk.

In the modern age, the rise of the easy creation and distribution of digital information and data has birthed a crisis of truth. There have been significant examples of misinformation in the politics and social exchanges of many nations worldwide.

The idea of “truth” in data is an interesting concept: it may refer to whether some data are factually correct or incorrect. Alternatively, truth may refer to whether data are current and up-to-date or whether they are old and no longer valid.

To date our erstwhile attempts to maintain truth in medical data has meant that patients’ data must be confined inside the hallowed data silos of medical institutions and practices. This has lead to data fragmentation between institutions, a lack of fluidity in appropriate data sharing, and a complete absence of effective self-ownership between a patient and his/her medical records.

In healthcare, data fragmentation further erodes the idea of truth: the “true” medical record of a patient who is seen at multiple medical institutions is a function of the full set of records across all institutions, but none individually.

Blockchains may go far in answering these problems in medicine and so it is no wonder that there is much excitement in what the technology promises. A single unified medical record which is managed and shared by the record’s owner via granting and revoking of cryptographic access would be an impressive improvement to current practices, data provenance, and patient rights. But how blockchains as a technology fully map to the domains of safe and secure healthcare delivery is still to be discovered


For blockchains to be applied to problems in healthcare a well-defined and concise problem or problem set must first be defined. The problem or problems must be poorly or incompletely answered by modern day solutions as they are likewise well-suited to the strengths of a blockchain.

Is there a need for transparent provenance and tracking of data and is there a clear benefit to decentralization of data management?

Decentralization of healthcare records – as the most immediate example – is a lofty and important goal, but institutions must somehow be incentivized to find benefits in decentralizing the data over which they have historically had effective control. Too, current blockchains are facing some early problems with scalability as regards number of transactions per second.

Is there a want and need for immutable historical data?

The computer scientist Richard Hickey [5] in his seminal 2012 keynote “The Value of Values” [6] adroitly describes how our early digital adolescence and its hard limitations on the capacity of data storage imposed on us an incorrect understanding of data and time.

When A = 1 in the morning, but A = 2 in the afternoon we typically either (a) overwrite in our database the first equality with the second, or (b) concoct arbitrary “encounters” meant to artificially segregate data events. We ignore that A = 1 once was true, even when it no longer is.

Immutable data means equalities may be alternatively true at different points in time. But this requires us to change how we model our datastores; it requires us to fundamentally reverse how we think about data architecture.

A patient does not view his/her medical history as a grouping of arbitrary and artificial encounters with health care edifices, but rather as an uninterrupted series of personal evolutionary changes across time.


An initial token (or coin) offering (ITO or ICO) is the creation of a new digital currency on top of a (typically equally new) blockchain. The purpose and hope is to raise investment capital for the blockchain with increasing valuation of the new currency.

When the excitement around cryptocurrencies was at its all time high in December of 2017 it seemed that every idea, those both fledgling and mature [7], wanted to tie itself to the cryptocurrency buzz.

Although currencies are its most successful proof-of-concept, blockchains do not need a separate cryptocurrency to be useful. Nonetheless, given recent cuts in government-sponsored health research as well as increasing interests from commercial sectors, an initial token offering may be an important consideration for possible project funding.

The process of an ITO is still young and imperfectly understood. Vitalik Buterin of Ethereum has written a comprehensive article offering understanding and good detail into some ways organizations are experimenting with offerings [8]. Vlad Zamfir has written an equally valuable piece on safe token sales [9].

Legality is of course of primary importance. In 2013 the U.S. Treasury has classified bitcoin as a convertible decentralized virtual currency [10]. The U.S. Library of Congress keeps a frequently-updated record of digital currency regulation [11]. In all cases legal representation must be rational and familiar with tax and securities law, compliance, data privacy, and technology.

Choice of legal jurisdiction is an important consideration; many recommend a global perspective. Token events are frequently complex in structuring and the choice of jurisdiction will dictate by whom we would be regulated, to whom we can offer tokens, and particular legal encumbrances on national and international distributions.


Before committing to a medical blockchain several points must be addressed and answered.

There must be clear technical merits of such a project and any successful effort must solve problems unaddressable by more conventional approaches.

Trust at the levels of business, legal, and technical must be clear and, if a token is to be distributed, the plan and process for distribution must be transparent as must be the question of ongoing project and community sustainability.

That said, if these hurdles can be appropriately addressed, the promises of blockchains may ultimately lead to a new level of patient engagement and ownership, new heights of insight into personal and population health, and a new breadth of novel advancements in health architecture and data truth.

Life is an error-making and an error-correcting process, and nature in marking man’s papers will grade him for wisdom as measured both by survival and by the quality of life of those who survive. – Jonas Salk, American medical researcher and virologist

This article first appeared in AIMed Magazine 04, yours to download here.

Author Information & Headshot

Kevin Hall is an Pediatric Cardiologist at the Yale University School of Medicine where he directs the Pediatric Heart Failure and Cardiomyopathy Program. He trained in Pediatric Cardiology at the Children’s Hospital of Philadelphia, University of Pennsylvania and completed a Senior Fellowship in Heart Failure and Transplantation at Children’s Hospital Boston, Harvard Medical School. Kevin is active in medical research, has programmed computers since the 1980s, and is an active participant in national and international groups dedicated to mobile health research. WEB: TWITTER: @eugkev