Examining database persistence of ISO/EN 13606 standardized electronic health record extracts: relational vs. NoSQL approaches

BACKGROUND: The objective of this research is to compare the relational and non-relational (NoSQL) database systems approaches in order to store, recover, query and persist standardized medical information in the form of ISO/EN 13606 normalized Electronic Health Record XML extracts, both in isolation and concurrently. NoSQL database systems have recently attracted much attention, but few studies in the literature address their direct comparison with relational databases when applied to build the persistence layer of a standardized medical information system. METHODS: One relational and two NoSQL databases (one document-based and one native XML database) of three different sizes have been created in order to evaluate and compare the response times (algorithmic complexity) of six different complexity growing queries, which have been performed on them. Similar appropriate results available in the literature have also been considered. RESULTS: Relational and non-relational NoSQL database systems show almost linear algorithmic complexity query execution. However, they show very different linear slopes, the former being much steeper than the two latter. Document-based NoSQL databases perform better in concurrency than in isolation, and also better than relational databases in concurrency. CONCLUSION: Non-relational NoSQL databases seem to be more appropriate than standard relational SQL databases when database size is extremely high (secondary use, research applications). Document-based NoSQL databases perform in general better than native XML NoSQL databases. EHR extracts visualization and edition are also document-based tasks more appropriate to NoSQL database systems. However, the appropriate database solution much depends on each particular situation and specific problem. This research has been partially supported by projects PI12/00508 “Plataforma de innovación en nuevos servicios de Telemedicina y e-Salud: Definición, diseño y desarrollo de herramientas para interoperabilidad, seguridad del paciente y ayuda a la decisión (Innovation platform in new services based on Telemedicine and e-Health: definition, design and development of tools for interoperability, patient security and support to decision) – PITES-ISA”, PI15CIII/00003 “Plataforma de innovación en Telemedicina y e-Salud: TIC para los retos de I+i en servicios de salud (Platform for Innovation in Telemedicine and e-Health: ICT for the challenges of I + i in health services) – PITES-TIiSS”, PI12/01476, PI12/01558, PI12/01399 “Continuidad de la asistencia basada en estándares de tecnología y conocimiento: arquitectura tecnológica para usos primario y secundario de la información (Continuity of care based on technology and knowledge standards: technological architecture for primary and secondary information uses.) – CAMAMA2” and PI15CIII/00010 - PI15/00321 - PI15/00831 “Modelo normalizado de historia clínica electrónica compartida para la asistencia sanitaria y social integrada. Factibilidad y utilidad de un repositorio de uso secundario en cáncer de mama (Standard model of shared electronic health record for integrated helath and social care. Feasibility and usefulness of a repository for secundary use for breast cancer patients.) – CAMAMA 3” from Fondo de Investigación Sanitaria (FIS) Plan Nacional de I + D + i. Sí