Classifying structural joint damage in rheumatoid arthritis as progressive or nonprogressive using a composite definition of joint radiographic change: a preliminary proposal.

OBJECTIVE

To categorize radiographic joint damage as progressive or nonprogressive in individuals with rheumatoid arthritis (RA) participating in clinical studies.

METHODS

Using the total Sharp radiographic damage score, erosion score, and joint space narrowing (JSN) score for 751 serial films of the hand/wrist and forefoot obtained from 190 patients with early RA during 6-60 months of followup (mean 31 months), various threshold values for progression of joint damage were evaluated singly and in various combinations. For each patient, the progression rate was estimated from the linear regression line for all available radiographic time points. After preliminary screening, 23 candidate definitions were tested to select a definition that discriminated well between radiographic progression and radiographic nonprogression.

RESULTS

The definition selected describes radiographic nonprogression in individual patients as an increase of < or =0.1 in the standardized response mean of the trimmed population (the central 95% of patients) for > or =5 of 6 change measures (erosion scores and JSN scores for the fingers, wrists, and feet). Using this definition, 59% of the 190 patients with early RA were defined as having nonprogressive radiographic damage. Moreover, 95% of 95 patients with progression of the total Sharp score at or below the median and 24% of 95 patients with progression of the total Sharp score above the median were defined as having nonprogressive joint damage (chi(2) = 98, P < 0.0001), as were 97% of patients in the lowest quintile of total Sharp score progression rates and none of the patients in the highest progression quintile. Patients defined as nonprogressors had significantly lower baseline levels of C-reactive protein and lower erythrocyte sedimentation rates compared with patients defined as progressors, and those patients in the nonprogressive joint damage group more frequently had American College of Rheumatology 20% and 50% improvement criteria responses, "good" improvements (decrease of > or =1.2) in the Disease Activity Score, and > or =50% decreases in the swollen joint counts during the first 2 years of followup.

CONCLUSION

RA joint damage in an observational cohort can be classified as progressive or nonprogressive with the use of a composite definition. Validation and/or refinement of this definition is needed by utilizing the data from controlled clinical trials that compare placebo with active treatment.