To compare computerised and conventional methodology of radiographic joint destruction assessment in early rheumatoid arthritis (RA).
We investigated the contribution of the 3rd-to-5th carpometacarpal joints (CMC3-5, which are excluded in computerised assessment so far owing to bone overlapping) to total joint space narrowing (JSN) scores in two cohorts of patients with early RA (n=392). Next, we investigated agreement between JSN scoring using single time point individual joint-based method (individual joint of a single time point (IJSTP), reflecting computerised reading) and conventional JSN scoring using the Sharp-van der Heijde (SvdH) method in a cohort of patients with early RA (n=59). We used intraclass correlation coefficients (ICCs), Bland and Altman plots, and linear mixed modelling to analyse differences in progression between two methods. Radiographs were available at baseline, and at 1 and 2 years of follow-up.
Of all joints affected by JSN at baseline or JSN progression during 2 years of follow-up, 3.9% and 6.6% concerned CMC3-5. Exclusion of CMC3-5 resulted in a decrease of 1.9-4.6% in JSN progression scores during 2 years of follow-up. The ICCs for JSN progression scores using IJSTP with or without CMC3-5 compared with SvdH were 0.71-0.81 and 0.69-0.78 at 1 and 2 years of follow-up. Signal-to-noise ratios for IJSTP-based and SvdH scoring were 0.51 and 0.58, respectively. The progression rate for each year was not statistically significantly different between two scoring methods (p=0.59 and 0.89).
This study showed that excluding CMC3-5 has limited influence on JSN (progression) scores and showed the feasibility of using IJSTP-based reading for computerised scoring of JSN (progression) in RA.