Objectives To investigate the longitudinal relationship between physical disability and US7S in a prospective cohort of patients with RA.
Methods A cohort of 205 RA pts (49 incident/156 prevalent) (mean±SD age 55±14 years, 47% RF+, 63% ACPA+, DAS28-CRP 3.7±1.5, mHAQ 0.43±0.52, disease duration in incident vs. prevalent pts. 0.9±0.7 vs. 8.1± 8.3 resp.) was followed up longitudinally for 29±9 months. Assessments at baseline and at month 3 and 6, and then every 6 months comprised DAS28-CRP, functional evaluations using the modified Health Assessment Questionnaire (mHAQ) and an ultrasound assessment of the clinically dominant hand and foot by US7S1. US7S consists of 5 subscores for synovitis (syn) and tenosynovitis (ten) assessed by grey-scale (GS) and Power-Doppler (PD), and an erosions score (ES). A linear mixed model was used to assess the longitudinal relationship between US7 subscores and mHAQ. Univariate analyses with an interaction term for incident vs. prevalent disease, and a multivariate analysis (with age, sex, BMI, RF and ACPA status, and DAS28-CRP entered as covariates) were performed.
Results In univariate analyses (table) mHAQ was longitudinally associated with GSsyn, PDsyn, PDten and GSten US7 subscores (with resp. β coefficients significantly higher in incident patients), while erosions score was a significant predictor of mHAQ only in prevalent pts. In a multivariate model the US7 subscores were individually no longer significant predictors of mHAQ, although the R2 of the model was improved by addition of US7 items from 43.6 to 46.9 (p<0.001 for improvement of R2).
Conclusions This study provides evidence that RA related activity and damage reflected by US7S contribute to impaired physical function in RA, and their impact differs in early and established disease. When combined with conventional clinical parameters, the additional explanatory value of US7 for mHAQ was only minor.
Backhaus M. et al. Evaluation of a novel 7-joint ultrasound score in daily rheumatologic practice: a pilot project. Arthritis Rheum. 2009 Sep 15;61(9):1194–201
Acknowledgement This work was supported by the project (Ministry of Health, Czech Republic) for consensual development of research organization 023728, and IGA grant NT12437
Disclosure of Interest None declared