title: MELLO: Medical lifelog ontology for data terms from self-tracking and lifelog devices.
abstract: OBJECTIVE
  The increasing use of health self-tracking devices is making the integration of heterogeneous data and shared decision-making more challenging. Computational analysis of lifelog data has been hampered by the lack of semantic and syntactic consistency among lifelog terms and related ontologies. Medical lifelog ontology (MELLO) was developed by identifying lifelog concepts and relationships between concepts, and it provides clear definitions by following ontology development methods. MELLO aims to support the classification and semantic mapping of lifelog data from diverse health self-tracking devices.
  
  
  METHODS
  MELLO was developed using the General Formal Ontology method with a manual iterative process comprising five steps: (1) defining the scope of lifelog data, (2) identifying lifelog concepts, (3) assigning relationships among MELLO concepts, (4) developing MELLO properties (e.g., synonyms, preferred terms, and definitions) for each MELLO concept, and (5) evaluating representative layers of the ontology content. An evaluation was performed by classifying 11 devices into 3 classes by subjects, and performing pairwise comparisons of lifelog terms among 5 devices in each class as measured using the Jaccard similarity index.
  
  
  RESULTS
  MELLO represents a comprehensive knowledge base of 1998 lifelog concepts, with 4996 synonyms for 1211 (61%) concepts and 1395 definitions for 926 (46%) concepts. The MELLO Browser and MELLO Mapper provide convenient access and annotating non-standard proprietary terms with MELLO (http://mello.snubi.org/). MELLO covers 88.1% of lifelog terms from 11 health self-tracking devices and uses simple string matching to match semantically similar terms provided by various devices that are not yet integrated. The results from the comparisons of Jaccard similarities between simple string matching and MELLO matching revealed increases of 2.5, 2.2, and 5.7 folds for physical activity,body measure, and sleep classes, respectively.
  
  
  CONCLUSIONS
  MELLO is the first ontology for representing health-related lifelog data with rich contents including definitions, synonyms, and semantic relationships. MELLO fills the semantic gap between heterogeneous lifelog terms that are generated by diverse health self-tracking devices. The unified representation of lifelog terms facilitated by MELLO can help describe an individual's lifestyle and environmental factors, which can be included with user-generated data for clinical research and thereby enhance data integration and sharing.
authors.affiliation: Seoul National University Biomedical Informatics (SNUBI), Division of Biomedical Informatics, Seoul National University College of Medicine, Seoul 110799, South Korea.
authors.forename: Hye Hyeon
authors.initials: HH
authors.lastname: Kim
authors.affiliation: Seoul National University Biomedical Informatics (SNUBI), Division of Biomedical Informatics, Seoul National University College of Medicine, Seoul 110799, South Korea.
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Seoul National University Biomedical Informatics (SNUBI), Division of Biomedical Informatics, Seoul National University College of Medicine, Seoul 110799, South Korea.
authors.forename: Su Youn
authors.initials: SY
authors.lastname: Baik
authors.affiliation: Seoul National University Biomedical Informatics (SNUBI), Division of Biomedical Informatics, Seoul National University College of Medicine, Seoul 110799, South Korea; Systems Biomedical Informatics National Core Research Center (SBI-NCRC), Seoul National University College of Medicine, Seoul 110799, South Korea. Electronic address: juhan@snu.ac.kr.
authors.forename: Ju Han
authors.initials: JH
authors.lastname: Kim
mesh_terms: D064229:Biological Ontologies; D057286:Electronic Health Records / Q000458:organization & administration*; D016247:Information Storage and Retrieval / Q000379:methods*; D008499:Medical Records; D056910:Republic of Korea; D012648:Self Care / Q000295:instrumentation / Q000379:methods*; D009626:Terminology as Topic
keywords: Consumer health; Lifelog; Ontology