In this article my colleague Jorden Woods (Co-Founder at DoubleNova Group) and I discuss the advantages, opportunities and challenges related to applying blockchain and distributed ledger technology (DLT) to healthcare. We are taking a data-centric perspective as data is at the heart of digital healthcare\u200a\u2014\u200aspecifically, data access & storage, security and trust. Today, digital healthcare is based in large part on electronic health records (EHRs). The promise of EHRs is that with better access to patient data, medical errors and costs can be reduced, and patient safety and outcomes can be improved. From a physician\u2019s perspective, if a doctor can quickly access a comprehensive record of your specific condition and medical history he or she can provide a better diagnosis and treatment which should provide a better, more cost effective outcome. From a patient\u2019s perspective knowing that the doctor has a complete understanding of your condition with historical context, creates a greater bond and sense of trust. However, ready access to comprehensive patient data through EHR systems has been riddled with problems. Patient data is generally fragmented across many healthcare stakeholders since different providers often use different EHR systems. Interoperability challenges often silo the data so that it stays where it was collected. Additionally, poor security protocols at many healthcare facilities have made centralized EHR systems easy targets for hackers who have stolen millions of patient records or created chaos with ransomware attacks. Due to these security breaches, many healthcare facilities have become wary of sharing or transferring EHRs for fear of further breaches, unwelcome negative media attention, and loss of community trust. Since patient data is stored with multiple stakeholders and fragmented, it is not easily shareable as a comprehensive historical record. For example, cancer patients may have their CAT scans stored at different labs, radiology notes located with various radiologists, their chemotherapy records at a number of hospitals, other visits and notes (in disparate electronic formats) with various other providers, medication records with pharmacies, medication adherence records with other companies, etc. Any potential solution must therefore work well in a decentralized ecosystem as well as improve trust and interoperability between different stakeholders. Advantages There are 3 pillars of blockchain technology that are directly applicable and advantageous for healthcare: \tUltra-secure and immutable store of information \tDecentralization of transactions \tBuilt-in gamification We discuss these pillars in more detail below. Ultra-secure and immutable store of information An ultra-secure store of information is exactly what the healthcare sector needs to eliminate the pervasive hacking and ransomware attacks plaguing the industry. With blockchain technology implemented at its fullest potential, patients and healthcare professionals could freely share health data without fear of hacking. An additional benefit of placing healthcare data into a secure blockchain data store is that it provides greater data transparency. Lack of transparency in the healthcare sector has led to insurance and billing fraud which has escalated into the tens of billions of dollars. Since all medical costs and procedures could be made accessible in the context of the patient\u2019s medical treatment, with the data cryptographically signed and encrypted, blockchain would also likely reduce the incidence of fraud and errors. Blockchain based systems have the potential to enable greater trust between all stakeholders because they could all share the same complete historical health information. The days of healthcare professionals acting on limited information or patients struggling to remember or endlessly repeating the specifics of their medical history would diminish. Decentralization of transactions As healthcare data is already distributed across multiple stakeholders, the blockchain\u2019s distributed ledger technology (DLT) infrastructure could be much better than existing centralized systems for accessing, extending and securing the data. Decentralized systems could also streamline costs, reduce time for transactions, and be more efficient than centralized systems due to lower overhead and fewer intermediaries. Due to regulatory constraints it may not be possible to fully decentralize the healthcare system with blockchain. Instead, trusted ecosystem players such as hospitals, insurance companies, clinics, labs and health information exchanges (HIEs) may become part of the processing fabric of the system since they could still store and process patient data. Built-in Gamification Tokenization of services and use of tokens creates many opportunities for incentivizing or \u2018paying\u2019 patients and healthcare ecosystem stakeholders to pursue beneficial activities. This can include block rewards for nodes that secure the blockchain (consensus protocol rewards) or process transactions. It can also include token rewards for pursuing healthier lifestyle activities (i.e. better diet, more exercise, fewer vices) or sharing healthcare data with the medical community and\/or pharmaceutical companies. Gamification techniques have proven effective for specific healthcare applications, especially those focused on positive behavior modification, but they have not yet been applied at scale. Blockchain applications that optimize their incentive mechanics can be the drivers that enable healthcare ecosystem players to achieve their goals faster and more uniformly worldwide. Opportunities In the prior section we discussed the advantages of using blockchain technology in the healthcare ecosystem. In this section we address specific use cases that have shown or will likely show strong positive results from the adoption of blockchain technology. Key data-centric use cases we believe have great promise include: \tPersonal Health Record (PHR) \tPopulation Health \tPersonalized Medicine We discuss these opportunities in more detail below. Personal Health Record (PHR) One of the most important elements of the healthcare blockchain ecosystem will be the PHR. It is a key building block of the ecosystem because it will contain a full record of each person\u2019s medical history, including treatment history from providers, patient-generated health data, and a summary of patient health information, including: \tpersonal identification \tvitals \tfamily medical history \tmedical conditions \tmedications \tallergies \timmunizations \tdiet restrictions \tgenomic data The concept of a PHR is not new and many companies have tried to develop and popularize their version of it since the early 2000\u2019s; however, inadequate security and interoperability have curtailed adoption. Blockchain technology has the ability to make secure PHRs a reality. Mass adoption is possible if users can embrace blockchain-based healthcare dApps (decentralized Apps) and smart contracts on mobile devices worldwide. To comply with regulations (i.e. HIPAA), each PHR should be owned by the individual, since the data is rightfully theirs. Also, most solutions envision that each person controls the level of access to the data and can even charge for access via blockchain technology\u2019s smart contracts. A key idea in the blockchain community is that individuals should be able to control and monetize any information connected to their digital identities. Some of the more effective blockchain-based PHR solutions ensure that each PHR has a unique digital address, that data is fully encrypted and cryptographically signed, and that it is interoperable with common EHR systems. By being an integral part of the blockchain ecosystem, all authorized stakeholders will have ready access to the latest version of a person\u2019s PHR, though as we\u2019ve noted above access could be partially restricted or may require payment. Key PHR use cases include doctors quickly accessing comprehensive patient information to optimize care and pharmaceutical companies accessing PHRs for use in virtual clinical trials. Overall, blockchain-based PHRs have the potential to improve healthcare outcomes and reduce costs by increasing speed and efficiency in the management of health data. They can also accelerate the transition to patient-centric healthcare by putting the patient and the patient\u2019s data at the center of the healthcare ecosystem. Population Health Population health data is medical information that is specific to a particular demographic. For example, it may be health risk information for Hispanic women 65\u201380 years old with diabetes. The data is usually provided in an anonymized form (no personal identifying information) and is generally used to understand risks across diverse populations. The largest challenges for population health management include data security, shareability, and interoperability. This is because patient information is siloed, insecure, and stored in different EHR systems which cannot easily exchange information with others. As a result, there is a scarcity of usable population health data sets across diverse patient populations. Blockchain technology provides a strong solution for these specific challenges. The key benefits of applying blockchain to population health data include improved: \tSecurity \tShareability \tInteroperability (for on-chain data) \tData integrity \tReal-time update and access Another benefit is that blockchain technology can enable participants in population health studies to monetize their data. By enabling the better collection and sharing of population health data, blockchain technology can assist in improving care delivery across diverse populations. With more population health data it will be possible to use advanced technologies such as artificial intelligence (AI) and machine learning (ML) algorithms to discover widespread, though potentially hidden, population health risks. For example, the combination of big data and better algorithms can help healthcare providers to find and prioritize at risk and underserved patient pools to enhance care and reduce societal risks (i.e. the opioid epidemic). Healthcare globally is moving away from a fee for service model towards a value-based care model. That is, patients pay for results and positive outcomes rather than just services. Today value-based care drivers incentivize better and more pervasive use of population health data. In the US, Medicare and Medicaid (CMS: Centers for Medicare & Medicaid Services) are now providing financial incentives to healthcare organizations to use population health data to reduce costs and improve the health of the patient populations they serve. Blockchain technology has the potential to make this vision a reality. Personalized Medicine Blockchain has the ability to make personalized medicine mainstream. Personalized medicine is defined as treatment that is tailored to an individual based on their health data including medical history and genetics. Because blockchain can facilitate ready access to a person\u2019s PHR and to relevant population health data, healthcare providers may soon provide routine individualized treatment. Consider the following example in the near future: an asthmatic African American man suffering from heart palpitations and severe headaches goes to a clinic and provides his PHR. The clinic accesses the PHR and then uses AI-based tools to select appropriate population health data to provide a list of 3 potential diagnoses. The doctor selects the most likely diagnosis and then queries the system for the best treatment options based on the population health data. The doctor then selects the treatment option which will provide a quick, cost-effective and favorable outcome for the patient. The blockchain\u2019s enhanced data security, shareability, and interoperability combined with advanced technologies, such as big data, AI and ML, will enable the next revolution in healthcare delivery. Other Use Cases There are other blockchain use cases for the healthcare industry that we do not cover in detail but would like to mention. These cases include: \tBeneficial behavior modification programs (fitness, diet, vice management) \tMedical products supply chain tracking \tMedication tracking and provenance \tMedical treatment audit trail \tMedical billing audit trail \tPatient consent management \tVirtual clinical trial management Challenges Some of the key challenges associated with the adoption of blockchain and DLT in healthcare have to do with the early stage of the technology. These issues include few successful use cases, slow transaction speeds, lack of scalability, and limited storage capacity. Other challenges are more fundamental to the healthcare industry. These challenges include: \tPlayers are late adopters of technology \tTransition from paper to digital data still in process \tEcosystem players not always willing to share information \tMedical data, especially images, are too large for current blockchain storage \tData interoperability is in early stages across the industry \tRegulatory environment is cautious and slows progress Though many challenges exist to adoption, early adopters in the industry already see the benefits of using blockchain technology and are working on various promising projects like we\u2019ve discussed. We believe the challenges can be overcome and blockchain will form a foundation for many innovative healthcare programs in the days ahead.