Clinical validation of joint index vector

Abstract

［Objectives］

The joint index vector（JIV）developed by Nishiyama is attracting attention as a new index of disease activity of rheumatoid arthritis（RA）. JIV was validated using monitoring data on RA cases in our institute.

［Methods］

The simplified disease activity index（SDAI）, the Health Assessment Questionnaire Disability Index（HAQ）, the Sharp/van der Heijde score（SHS）, the pain score（PS）and the EQ5D, which have been monitored every visit for RA patients since January 2016 in our hospital, are defined as dependent factors, and the 3-axis coordinates of JIV（Vx, Vy, Vz）are defined as independent factors to statistically examine the correlation between the mean values of each index at the first visit（BL）, 1 year after the first visit（1Y）and at the last visit（LV）. The change in HAQ score and SHS（dSHS）at 1Y was defined as the dependent variable, and the correlation with each JIV coordinate was statistically examined.

［Results］

419 people were surveyed. All of the dependent variable except for Fatigue at LV and EQ5D at BL were significantly correlated with one of the triaxial elements of JIV. Vz was significantly correlated with HAQ score in 1Y. There was a significant correlation between dSHS and Vx, Vy and annual change of Vx（dVx）, except for the length of history of RA.

［Conclusion］

JIV is an index that correlates with each clinical index and is suitable as a guide to describe the affected state of the joint.