The characteristic joint damage and disability of rheumatoid arthritis (RA) increase slowly over 10-20 yr. Although it is generally believed that persisting inflammatory synovitis causes joint damage and subsequent disability, the strength of their relationship has not been systematically evaluated. This review describes their progression and interrelationship in treated RA.
MEDLINE and Current Contents databases were searched for the combined terms of rheumatoid arthritis AND X-rays, Health Assessment Questionnaire, slow-acting anti-rheumatic drugs and all identifiable synonyms. This search identified 1303 articles and from these we evaluated in detail 23 reports on the progression of joint damage, 12 reports on the progression of disability and 25 reports dealing with their interrelationship. Additional information was obtained from four data sets comprising 725 RA patients studied cross-sectionally and 33-126 cases followed prospectively for 1-5 yr. X-ray damage was primarily assessed by Larsen and Sharp indices, and disability by the Health Assessment Questionnaire (HAQ).
Joint damage and disability both increase throughout the duration of RA. Although disability (HAQ score) is correlated with disease duration (correlation coefficients between 0.27 and 0.30), the link between X-ray damage and disability is stronger (correlation coefficients between 0.30 and 0.70). In the earliest phases of RA, X-ray damage and HAQ scores are not related. By 5-8 yr, there are significant correlations with correlation coefficients between 0.30 and 0.50. In late RA (>8 yr), most studies show highly significant correlations between 0.30 and 0.70.
Joint damage progresses constantly over the first 20 yr of RA. It accounts for approximately 25% of disability in established RA. The link between damage and disability is strongest in late (>8 yr) RA. However, avoiding or reducing joint damage in both early and established/late RA is likely to maintain function.