Introduction: The objectives of this study were to determine the predictive factors of long-term radiographic outcome of rheumatoid arthritis (RA) and to describe the relationship between joint damage and disability over the course of the disease.
Methods: A cohort of 191 patients with early RA referred from primary care physicians were prospectively followed for 10 years. To determine the predictive factors of radiographic outcome, univariate analysis of the relationship between baseline values and outcome measures was undertaken using a chi-squared or Fisher's exact test. Stepwise multiple logistic regression was also performed to select independent prognostic factors.
Results: From data available for 112 patients, univariate analysis revealed a total Sharp score at 10 years that was significantly correlated with erythrocyte sedimentation rate (ESR), presence and level of IgA rheumatoid factor, presence of an anti-citrullinated protein antibody (ACPA), serum level of matrix metalloproteinase-3 and radiographic score at baseline. Logistic regression identified the baseline erosion score to be the most important baseline parameter as an independent prognostic factor of total radiographic score at 10 years (odds ratio = 5.64; 95% confidence interval = 1.78 to 17.86). After excluding radiographic scores from the entry parameters, the presence of ACPA and ESR were also predictive of the final total Sharp score. The Health Assessment Questionnaire (HAQ) score was strongly correlated with disease activity parameters, such as disease activity score and pain, at baseline and at three, five and 10 years. No correlation was found between total radiographic Sharp score and HAQ score throughout the study.
Conclusions: In this prospective study, baseline radiographic score, ESR and ACPA were the best predictive factors of 10-year radiographic outcome in early RA. HAQ disability was associated with disease activity throughout the 10-year follow-up but not with joint damage. This discrepancy with previous reports may be due in part to the early start of therapy with disease-modifying anti-rheumatic drugs.