There are multiple definitions:

1. resistance island(English)

   • multiple resistance genes clustered within the same genetic locus, and these can be transferred en bloc to other organisms. Genes conferring simultaneous resistance to different classes of antimicrobials, confer a selective advantage to the host, particularly when those corresponding antibiotics are administered; also denoted as RI
   • RI
   • Genetics, Bacteriology, Gene cluster
   • https://doi.org…inf.2005.12.027

2. relative efficiency index(English)

   • a measure of responsiveness
   • cSLE, ECLAM, SLE, SLEDAI
   • Rheumatology
   • https://doi.org….1002/art.11111

3. Rachmilewitz endoscopic index(English)

   • EI, UC
   • Gastroenterology, Medical imaging
   • https://doi.org…2328-008-0018-z