Background No consensus exists on which joints and tendons should be systematically examined by ultrasound (US) to assess inflammation in rheumatoid arthritis (RA). Validity and responsiveness must be balanced against feasibility. Our group has previously developed and validated an US joint inflammation score1.
Objectives To optimize the US joint inflammation score in terms of sensitivity to change and feasibility, and to validate the score in a separate cohort.
Methods Between Jan 2010 and June 2013 patients (pts) were included in two cohorts: Early RA (DMARD-naïve pts with RA of <2 yrs symptom duration fulfilling 2010 ACR/EULAR classification criteria), and established RA (pts starting or switching biologic DMARDs). An extensive US examination was performed by experienced sonographers using a validated grey-scale (GSUS) and power Doppler (PDUS) semi-quantitative scoring system with scores 0–3 for GSUS and PDUS in each of the following 36 joints and 4 tendons bilaterally: MCP 1–5, PIP 2–3, radiocarpal, distal radioulnar (DRUJ), intercarpal, elbow, knee, talocrural, MTP 1–5, extensor carpi ulnaris (ECU) and tibialis posterior (TP) tendons. An US atlas was used as reference2. We performed principal component factor analyses (PCA) of GSUS and PDUS changes from baseline to 3 months (ΔGSUS and ΔPDUS) to identify joint groups with high internal correlation, and selected a candidate joint/tendon set based on these analyses. 3- and 6-month standardised response means (SRMs) with 95% CIs (bootstrapping) were estimated for the candidate set and 3 formerly developed scores in both the early RA cohort and the validation cohort of established RA. Finally, as part of the validation, we assessed the loss of information in the novel score compared to the full score by R2 from linear regression analyses in both cohorts.
Results A total of 330 pts were included, 118 with early and 212 with established RA; 71% vs. 81% anti-CCP pos, mean (SD) age 51 (13) vs. 52 (13) yrs, DAS28 4.7 (1.2) vs. 4.7 (1.4), median (25–75 perc) 28-SJC 6 (3–11) vs. 5 (2–10), disease duration 0.5 (0.2–0.8) vs. 8 (3–15) yrs. We identified 12 joint/tendon groups based on PCA in the early RA data, and 8 joints* and 1 tendon* were included in the final score based on these results (Table). SRMs at 3 and 6 months were higher for the novel score than formerly developed scores in the early RA cohort, with similar results in the validation cohort of established RA (Fig). Based on baseline data from the early RA cohort, the final score retained 87% (GSUS) and 90% (PDUS) of the information in the full score. The corresponding numbers in the validation cohort were 90% (GSUS) and 92% (PDUS).
Conclusions We used a data-driven approach to further develop an ultrasound inflammation score in RA. We propose a score of 8 joints and 1 tendon assessed bilaterally, with improved sensitivity to change compared to formerly developed scores. Our results show that assessment of inflammation by US is feasible and may be a valuable addition to RA disease assessment.
Aga et al ARD 2015,
Hammer et al ARD 2011,
Naredo et al Arthritis Rheum 2008,
Backhaus et al Arthritis Rheum 2009,
Perricone et al Rheumatology 2012.
Disclosure of Interest A.-B. Aga: None declared, E. Lie: None declared, I. Olsen: None declared, H. Hammer Grant/research support from: AbbVie, BMS, Pfizer, Roche, UCB, T. Uhlig: None declared, S. Lillegraven: None declared, D. van der Heijde: None declared, T. Kvien: None declared, E. Haavardsholm Grant/research support from: AbbVie, MSD, Pfizer, Roche, USB