Sub-clinical inflammation predicts structural progression in RA:
Structural deterioration occurs in rheumatoid arthritis (RA) patients despite the presence of clinical remission, results of a prospective longitudinal study show.
"Such deterioration is associated with synovitis detected by imaging techniques," say Paul Emery (University of Leeds, UK) and co-authors in the journal Arthritis and Rheumatism.
Emery and colleagues previously demonstrated a high prevalence of imaging-detected synovial inflammation in RA patients who were in clinical remission. These findings lead them to generate the hypothesis that sub-clinical inflammation detected by imaging may explain the structural progression reported in these patients.
To investigate, the team studied 102 RA patients receiving conventional treatment who had been judged by their consultant rheumatologist to be in remission, as well as 17 healthy control individuals.
Participants underwent clinical, laboratory, functional, and quality of life assessments over a 12 month period. In addition to standard radiography of the hands and feet, imaging of the hands and wrists was performed with musculoskeletal ultrasonography (US) and conventional 1.5T magnetic resonance imaging (MRI) at baseline and 12 months, using validated acquisition and scoring techniques.
Despite being in clinical remission, 19% of the patients displayed deterioration in radiographic joint damage over the study period. Scores on musculoskeletal US synovial hypertrophy, power Doppler (PD), and MRI synovitis assessments in individual joints at baseline were significantly associated with progressive radiographic damage.
Furthermore, there was a significant association between the musculoskeletal US PD score at baseline and structural progression over 12 months in asymptomatic metacarpophalangeal joints, and a 12 times greater risk for deterioration in joints with increased PD signal.
The authors conclude: "This study is the first to demonstrate that subclinical inflammation detected by imaging techniques may predict subsequent radiographic outcome in clinically asymptomatic joints."
"These data support our hypothesis that subclinical inflammation, which is undetectable by traditional measurement techniques, is the pathophysiologic mechanism for continued structural progression in RA despite apparent clinical remission."