CMEO: Clinical Metadata Exploration Ontology

Integrating clinical research data across institutions is challenged by heterogeneity in variable definitions, inconsistent use of terminologies, and limited support for interoperable metadata. Biomedical ontologies offer important resources for structuring clinical data, yet their integration for comprehensive metadata descriptors (such as variable semantics, statistical summaries, and governance elements) is not yet well established. These descriptors are critical for data discovery and harmonization. We introduce the Clinical Metadata Exploration Ontology (CMEO), a semantic framework that extends established ontologies including OBI, STATO, and DUO to provide a unified representation of study designs, data element properties (e.g., value sets, units), exploratory statistics, and data reuse permissions. CMEO enables semantic querying, cross-study comparison, and harmonization planning in settings where individual-level data cannot be shared. Access via: https://komi786.github.io/cmeo/