OMOP is establishing an open-source library of ten Health Outcomes of Interest (HOI) definitions for use in observational studies. HOI definitions are the critical focus for the central protocols as they bring to the OMOP investigators an evidence-based summary of prior observational research definitions and clinical guidelines. These definitions will allow OMOP to compare methods across different data sources using defined methods.

The initial set of OMOP HOI definitions can be accessed via the links below:

1. Angioedema
2. Aplastic Anemia
3. Acute Liver Injury
4. Bleeding
5. GI Ulcer Hospitalization
6. Hip Fracture
7. Hospitalization
8. Myocardial Infarction
9. Mortality after Myocardial Infarction
10. Renal Failure