We analyzed whether a patient self-report remission criterion, such as that according to the Rheumatoid Arthritis Disease Activity Index-5 (RADAI-5), meets the criteria of the 2011 proposed American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) definition of remission.
The 2 approaches of the ACR/EULAR proposal [Boolean- and Simplified Disease Activity Index (SDAI)-based] as well as the RADAI-5 were used to assess whether patients with RA are in remission. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), and kappa analyses were performed to illustrate the relationship among the different approaches defining remission at a group level.
In total, 705 patients' assessments were included. Eighty-nine patients were classified as being in remission according to the Boolean-based and 169 according to the SDAI-based definition of the ACR/EULAR proposals, and 154 according to the RADAI-5. Sixty-eight assessments were classified as being in remission according to all 3 definitions. In the case of RADAI-5 remission, sensitivity was 78%, specificity 86%, PPV 45%, and NPV 96%, indicating remission according to the Boolean-based definition; and 60%, 92%, 66%, and 90%, respectively, indicating remission according to the SDAI-based definition. In the case of remission according to the SDAI-based ACR/EULAR definition, sensitivity was 52%, specificity 100%, PPV 98%, and NPV 87%, also indicating remission according to the Boolean definition; while according to the Boolean definition the values were 98%, 87%, 52%, and 100%, respectively. Kappa statistics showed fair to good agreement for all 3 definitions.
Nearly twice as many assessments were classified as being in remission using the SDAI-based or the RADAI-5 definitions when compared to the Boolean-based definition. Remission according to the RADAI-5 also was highly specific for both ACR/EULAR criteria. Sensitivity for the RADAI-5 criterion was even better for the Boolean-based definition than that for the SDAI-based definition.