We are addressing existing problems with integration of healthcare information from Electronic Health Records (EHR) and Personal Health Records (PHR) systems because of structural and semantic heterogeneity. Existing ways of PHR- and EHR collection include harvesting medical and individual data from different data sources that store different medical, not standardized data. Such a heterogeneity increases the complexity of merging PHR and EHR and lack of qualitative trust between contracting parties. On the other hand, blockchains are inherently resistant to modification of the data and are secure by design. We focus on the integration process as a main aspect for solving the heterogeneity issue. Thereby, we aim at reducing the merging complexity by defining the requirements for PHR data collection and creating an ontology for a semantically sound data-set merger for personal-centric healthcare systems and we evaluate the results with formal means. To enable trust in decentralized sociotechnical healthcare system we use Ethereum smart contracts on top of the blockchain as a communication way in the context of multi-agent system.