Abstract Objectives: Electronic health record (EHR) can allow for the generation of large cohort of individuals with given diseases for clinical and genomic research. A rate-limiting step is the development of electronic phenotype selection algorithms to find such cohorts. This study evaluated the portability of a published phenotype algorithm to identify rheumatoid arthritis (RA) patients from HER records at three institutions with different EHR systems. Material and Methods: Physicians...