Gello Expression Language


The GELLO Expression Language was started in 2001 and introduced in 2002; in 2005, GELLO was adopted as an international standard by Health Level Seven International and ANSI for a decision support language. GELLO Release 2 was completed and approved by ANSI in June 2010.[1] The GELLO specifications have been developed in coordination with the HL7 Clinical Decision Support TC (CDSTC)[2]

GELLO is a class-based object-oriented programming language and a relative of the Object Constraint Language (OCL). OCL is a well-developed constraint language that makes it attractive for use as an expression language. The intention was for GELLO to evolve as a standard query and expression language for decision support.[3]

GELLO creates the potential for many decision support options, as the full array of atomic patient data is greatly accessible to complement better, safer clinical decision-making by health professionals. Furthermore, this enables specialist clinicians to customize their current systems and create flexible purpose built decision support systems.[4]

Standardization of GELLO has made this language compatible with the HL7 version 3.0 Reference Information Model (RIM). GELLO uses an abstract "virtual medical record" (vMR) so that the same GELLO code can run on multiple systems accessing data stored in different formats. The vMR is a simplified view of the HL7 RIM.[5]

The current focus of the HL7 CDS WG is to build on the Clinical Quality Language (CQL)[6]

Uses for GELLOEdit

The GELLO language can be used to:

  • Build up queries to extract and manipulate data from medical records.
  • Construct decision criteria by building up expressions to reason about particular data features/values. These criteria can be used in decision-support knowledge bases such as those designed to provide alerts and reminders, guidelines, or other decision rules.
  • Create expressions, formulae, and queries for other applications.[7]
  • GELLO was used with Guideline Interchange Format (GLIF), as it is the most expressive expression language in the context of GLIF.[8]

See alsoEdit


  1. ^ ANSI Approved Standards | HL7 International
  2. ^ "V3 Rules/GELLO". Archived from the original on 2010-04-02.[dead link]
  3. ^ Sordo, M; Boxwala, AA; Ogunyemi, O; Greenes, RA (2004). "Description and status update on GELLO: a proposed standardized object-oriented expression language for clinical decision support". Stud Health Technol Inform. 107 (Pt 1): 164–8. PMID 15360796.
  4. ^ "Archived copy". Archived from the original on 2016-09-22. Retrieved 2010-11-11.{{cite web}}: CS1 maint: archived copy as title (link)
  5. ^ VMR - Virtual Medical Record - Knowledgebase - Medical-Objects Knowledgebase
  6. ^ "HL7 CDS Standards". Retrieved 25 June 2019.
  7. ^ GELLO: An Object-Oriented Query and Expression Language for Clinical Decision Support
  8. ^ Wright, A; Sittig, D (2008). "A framework and model for evaluating clinical decision support architectures". Journal of Biomedical Informatics. 41 (6): 982–990. doi:10.1016/j.jbi.2008.03.009. PMC 2638589. PMID 18462999.