The Oswestry Disability Index (ODI) is a widely used spine-specific PRO instrument in orthopedics to assess disability related to back pain and functional improvement from treatment (Fairbank & Pynsent, 2000). 

The ODI has 10 patient-completed questions in which the response options are presented as 6-point Likert scales. Scores range from 0% (no disability) to 100% (most severe disability).

For details, see Tang et al (under review), Linking Oswestry Disability Index to the PROMIS Pain Interference CAT with equipercentile methods
PROMIS Pain Interference and ODI Linking Table
                         ​Linking Report