| PDI | pain disability index; periodontal disease index; plan-do integration; psychomotor development index... |
|---|---|
| RPI | regional perfusion index; relative percentage index; reticulocyte production index, ribose 5-phospha... |
| VI | Roman numeral six; vaginal irrigation; variable interval; vastus intermedius; virgo intacta; virulen... |
| AEI | arbitrary evolution index; atrial emptying index |
| AHI | active hostility index; Animal Health Institute; apnea-plus-hypopnea index |