1 Approaches for Guideline Versioning Using GLIF

Computer-interpretable clinical guidelines (CIGs) aim to eliminate clinician errors, reduce practice variation, and promote best medical practices by delivering patient-specific advice during patient en-counters. Clinical guidelines are being regularly updated and revised to handle expanding clinical knowledge. When revising CIGs, much effort can be saved by specifying changes among versions instead of encoding revised guidelines from scratch. A repre-sentation of differences between versions could focus the process of re-implementing CIGs in a clinical environment and help users understand and embrace changes. Guideline versioning has not been ade-quately dealt with by existing CIG formalisms. We present three approaches for CIG versioning. Focus-ing on one approach, we developed a versioning tool based on version 3 of the GuideLine Interchange Format (GLIF3), and used it to represent two guide-line versions for management of community-acquired pneumonia (CAP) and the changes between them.