Clinical Disease Activity and Radiological Damage in Early Rheumatoid Arthritis

Abstract

Disease progression in rheumatoid arthritis (RA) is assessed by standard clinical, radiological and functional measures. Clinical disease activity in RA is graded as no disease (remission), low, moderate and high disease, based on validated criteria. Radiological progression in RA is monitored by serial x-rays of hands and feet, and by quantification of structural damage, using various scoring methods. This proves to be a valuable outcome measure in RA studies. RA patients with active disease usually develop progressive radiological damage. However, it has been shown that clinical disease activity may not correlate with radiological damage, particularly in early RA. Therefore, this thesis was mainly aimed to test the hypothesis that, „radiological damage can progress despite clinical disease inactivity or remission‟ and to investigate possible underlying mechanisms including disease heterogeneity, treatment effect and scoring methodology. Disease progression, outcomes and prognostic factors were analysed in an inception cohort of early RA (Early Rheumatoid Arthritis Study/ERAS) for this thesis. In this study of early RA patients, sustained remission was less frequent than remission at individual time points and baseline variables such as gender, duration of symptoms, disease activity (DAS) and health assessment questionnaire (HAQ) scores have shown predictive value for sustained remission. Structural damage on x-rays progressed despite clinical disease inactivity or remission in a subgroup of patients and disease heterogeneity was the most likely explanation for the disconnect between clinical disease activity and radiological damage in the ERAS cohort. This study has also found that scoring methods as well as reading order of x-ray films could influence radiographic progression in early RA, particularly at individual level. Male sex, rheumatoid factor (RF) and radiographic damage at baseline showed prognostic value in predicting radiographic progression despite remission. Study patients with persistent clinical disease inactivity have shown better radiological, surgical, functional, and other outcomes compared to relapsing-remitting or persistent disease activity. There was no significant difference in functional and other outcomes between patients in remission with x-ray progression and those in remission without xray progression. Therefore, x-rays of hands and feet at regular intervals are valuable in determining true disease progression in early RA, even during clinical disease inactivity. Scoring methodology in itself could have an influence on the type of radiographic progression in RA studies. Sustained disease inactivity in RA is more favourable than relapsingremitting disease.